⚠️ Warning: This is a draft ⚠️

This means it might contain formatting issues, incorrect code, conceptual problems, or other severe issues.

If you want to help to improve and eventually enable this page, please fork RosettaGit's repository and open a merge request on GitHub.

{{task}} [[File:15_puzzle.png|300px|thumb|right]] [[Category:Puzzles]] [[Category:Games]]

;Task: Implement the [[wp:15_puzzle|Fifteen Puzzle Game]].

The '''15-puzzle''' is also known as: :::* '''Fifteen Puzzle''' :::* '''Gem Puzzle''' :::* '''Boss Puzzle''' :::* '''Game of Fifteen''' :::* '''Mystic Square''' :::* '''14-15 Puzzle''' :::* and many others.

;Related Tasks: :* [[15_puzzle_solver|15 Puzzle Solver]] :* [[16 Puzzle Game]]

Ada

We fist define a generic package Generic_Puzzle. Upon instantiation, it can take any number of rows, any number of columns for a rows*columns-1 game. Instead of plain numbers, the tiles on the board can have arbitrary names (but they should all be of the same length). The package user can request the name for the tile at a certain (row,column)-point, and the set of possible moves. The user can move the empty space up, down, left and right (if possible). If the user makes the attempt to perform an impossible move, a Constraint_Error is raised.

generic
   Rows, Cols: Positive;
   with function Name(N: Natural) return String; -- with Pre => (N < Rows*Cols);
   -- Name(0) shall return the name for the empty tile
package Generic_Puzzle is

   subtype Row_Type is Positive range 1 .. Rows;
   subtype Col_Type is Positive range 1 .. Cols;
   type Moves is (Up, Down, Left, Right);
   type Move_Arr is array(Moves) of Boolean;

   function Get_Point(Row: Row_Type; Col: Col_Type) return String;
   function Possible return Move_Arr;
   procedure Move(The_Move: Moves);

end Generic_Puzzle;

The package implementation is as follows.

package body Generic_Puzzle is

   Field: array(Row_Type, Col_Type) of Natural;
   Current_R: Row_Type := Rows;
   Current_C: Col_Type := Cols;
   -- invariant: Field(Current_R, Current_C=0)
   -- and for all R, C: Field(R, C) < R*C
   -- and for all (R, C) /= (RR, CC): Field(R, C) /= Field(RR, CC)

   function Get_Point(Row: Row_Type; Col: Col_Type) return String is
      (Name(Field(Row, Col)));

   function Possible return Move_Arr is
      (Up => Current_R > 1, Down => Current_R < Rows,
       Left => Current_C > 1, Right => Current_C < Cols);

   procedure Move(The_Move: Moves) is
      Old_R: Row_Type; Old_C: Col_Type; N: Natural;
   begin
      if not Possible(The_Move) then
	 raise Constraint_Error with "attempt to make impossible move";
      else
	 -- remember current row and column
	 Old_R := Current_R;
	 Old_C := Current_C;

	 -- move the virtual cursor to a new position
	 case The_Move is
	   when Up    => Current_R := Current_R - 1;
	   when Down  => Current_R := Current_R + 1;
	   when Left  => Current_C := Current_C - 1;
	   when Right => Current_C := Current_C + 1;
	 end case;

	 -- swap the tiles on the board
	 N := Field(Old_R, Old_C);
	 Field(Old_R, Old_C) := Field(Current_R, Current_C);
	 Field(Current_R, Current_C) := N;
      end if;
   end Move;

begin
   declare   -- set field to its basic setting
      N: Positive := 1;
   begin
      for R in Row_Type loop
	 for C in Col_Type loop
	    if (R /= Current_R) or else (C /= Current_C) then
	       Field(R, C) := N;
	       N := N + 1;
	    else
	       Field(R, C) := 0;
	    end if;
	 end loop;
      end loop;
   end;
end Generic_Puzzle;

The main program reads the level from the command line. A larger level implies a more difficult instance. The default level is 10, which is fairly simple. After randomizing the board, the user can move the tiles.

with Generic_Puzzle, Ada.Text_IO,
     Ada.Numerics.Discrete_Random, Ada.Command_Line;

procedure Puzzle_15 is

   function Image(N: Natural) return String is
      (if N=0 then "   " elsif N < 10 then " " & Integer'Image(N)
	else Integer'Image(N));

   package Puzzle is new Generic_Puzzle(Rows => 4, Cols => 4, Name => Image);

   package Rnd is new Ada.Numerics.Discrete_Random(Puzzle.Moves);
   Rand_Gen: Rnd.Generator;

   Level: Natural := (if Ada.Command_Line.Argument_Count = 0 then 10
                      else Natural'Value(Ada.Command_Line.Argument(1)));
   Initial_Moves: Natural := (2**(Level/2) + 2**((1+Level)/2))/2;
   Texts: constant array(Puzzle.Moves) of String(1..9) :=
       ("u,U,^,8: ", "d,D,v,2: ", "l,L,<,4: ", "r,R,>,6: ");
   Move_Counter: Natural := 0;
   Command: Character;

 begin
    -- randomize board
    for I in 1 .. Initial_Moves loop
       declare
	  M: Puzzle.Moves := Rnd.Random(Rand_Gen);
       begin
	  if Puzzle.Possible(M) then
	     Puzzle.Move(M);
	  end if;
       end;
    end loop;

    -- read command and perform move
    loop
      -- Print board
      for R in Puzzle.Row_Type loop
	 for C in Puzzle.Col_Type loop
	    Ada.Text_IO.Put(Puzzle.Get_Point(R, C));
	 end loop;
	 Ada.Text_IO.New_Line;
      end loop;
      Ada.Text_IO.Get(Command);
      begin
	 case Command is
	    when 'u' | 'U' | '^' | '8' =>
	       Ada.Text_IO.Put_Line("Up!"); Puzzle.Move(Puzzle.Up);
	    when 'd' | 'D' | 'v' | '2' =>
	       Ada.Text_IO.Put_Line("Down!"); Puzzle.Move(Puzzle.Down);
	    when 'l' | 'L' | '<' | '4' =>
	       Ada.Text_IO.Put_Line("Left!"); Puzzle.Move(Puzzle.Left);
	    when 'r' | 'R' | '>' | '6' =>
	       Ada.Text_IO.Put_Line("Right!"); Puzzle.Move(Puzzle.Right);
	    when '!' =>
	       Ada.Text_IO.Put_Line(Natural'Image(Move_Counter) & " moves!");
	       exit;
	    when others =>
	       raise Constraint_Error with "wrong input";
	 end case;
	 Move_Counter := Move_Counter + 1;
      exception when Constraint_Error =>
	 Ada.Text_IO.Put_Line("Possible Moves and Commands:");
	 for M in Puzzle.Moves loop
	    if Puzzle.Possible(M) then
	       Ada.Text_IO.Put(Texts(M) & Puzzle.Moves'Image(M) & "   ");
	    end if;
	 end loop;
	 Ada.Text_IO.Put_Line("!: Quit");
      end;
   end loop;
end Puzzle_15;

{{out}}

>./puzzle_15 4
  1  2  3  4
  5  6  7  8
  9 14 10 11
 13    15 12
8
Up!
  1  2  3  4
  5  6  7  8
  9    10 11
 13 14 15 12
6
Right!
  1  2  3  4
  5  6  7  8
  9 10    11
 13 14 15 12
5
Possible Moves and Commands:
u,U,^,8: UP   d,D,v,2: DOWN   l,L,<,4: LEFT   r,R,>,6: RIGHT   !: Quit
  1  2  3  4
  5  6  7  8
  9 10    11
 13 14 15 12
6
Right!
  1  2  3  4
  5  6  7  8
  9 10 11
 13 14 15 12
2
Down!
  1  2  3  4
  5  6  7  8
  9 10 11 12
 13 14 15
!
 4 moves!

For other puzzles, one must just the single line with the package instantiation. E.g., for an 8-puzzle, we would write the following.

   package Puzzle is new Generic_Puzzle(Rows => 3, Cols => 3, Name => Image);

APL

{{works with|Dyalog APL|16.0}}

fpg←{⎕IO←0
    ⍺←4 4
    (s∨.<0)∨2≠⍴s←⍺:'invalid shape:'s
    0≠⍴⍴⍵:'invalid shuffle count:'⍵
    d←d,-d←↓2 2⍴3↑1
    e←¯1+⍴c←'↑↓←→○'
    b←w←s⍴w←1⌽⍳×/s
    z←⊃{
        z p←⍵
        n←(?⍴p)⊃p←(p≡¨(⊂s)|p)/p←(d~p)+⊂z
        b[z n]←b[n z]
        -⍨\n z
    }⍣⍵⊢(s-1)0
    ⎕←b
    ⍬{
        b≡w:'win'
        0=⍴⍺:⍞∇ ⍵
        e=i←c⍳m←⊃⍺:'quit'
        i>e:⍞∇ ⍵⊣⎕←'invalid direction:'m
        n≢s|n←⍵+i⊃d:⍞∇ ⍵⊣'out of bounds:'m
        b[⍵ n]←b[n ⍵]
        ⎕←(s×0≠⍴⍺)⍴b
        (1↓⍺)∇ n
    }z
}

{{out}}

      fpg 10
 1  3  0  4
 5  2  6  8
 9 10  7 12
13 14 11 15
←
 1  0  3  4
 5  2  6  8
 9 10  7 12
13 14 11 15
↓
 1  2  3  4
 5  0  6  8
 9 10  7 12
13 14 11 15
→
 1  2  3  4
 5  6  0  8
 9 10  7 12
13 14 11 15
↓↓
 1  2  3  4
 5  6  7  8
 9 10 11 12
13 14  0 15
→
 1  2  3  4
 5  6  7  8
 9 10 11 12
13 14 15  0
win


      2 5 fpg 2
1 2 3 0 4
6 7 8 9 5
→
1 2 3 4 0
6 7 8 9 5
↓
1 2 3 4 5
6 7 8 9 0
win

ARM Assembly

{{works with|as|Raspberry Pi}}



/* ARM assembly Raspberry PI  */
/*  program puzzle15.s   */

/************************************/
/* Constantes                       */
/************************************/
.equ STDIN,  0     @ Linux input console
.equ STDOUT, 1     @ Linux output console
.equ EXIT,   1     @ Linux syscall
.equ READ,   3     @ Linux syscall
.equ WRITE,  4     @ Linux syscall

.equ IOCTL,     0x36  @ Linux syscall
.equ SIGACTION, 0x43  @ Linux syscall
.equ SYSPOLL,   0xA8  @ Linux syscall

.equ TCGETS,    0x5401
.equ TCSETS,    0x5402
.equ ICANON,    2
.equ ECHO,     10
.equ POLLIN,    1

.equ SIGINT,   2    @ Issued if the user sends an interrupt signal (Ctrl + C)
.equ SIGQUIT,  3    @ Issued if the user sends a quit signal (Ctrl + D)
.equ SIGTERM, 15    @ Software termination signal (sent by kill by default)
.equ SIGTTOU, 22    @

.equ NBBOX,  16
.equ TAILLEBUFFER,   10

/*******************************************/
/* Structures                               */
/********************************************/
/* structure termios see doc linux*/
    .struct  0
term_c_iflag:                    @ input modes
    .struct  term_c_iflag + 4
term_c_oflag:                    @ output modes
    .struct  term_c_oflag + 4
term_c_cflag:                    @ control modes
    .struct  term_c_cflag + 4
term_c_lflag:                    @ local modes
    .struct  term_c_lflag + 4
term_c_cc:                       @ special characters
    .struct  term_c_cc + 20      @ see length if necessary
term_fin:

/* structure sigaction see doc linux */
    .struct  0
sa_handler:
    .struct  sa_handler + 4
sa_mask:
    .struct  sa_mask + 4
sa_flags:
    .struct  sa_flags + 4
sa_sigaction:
    .struct  sa_sigaction + 4
sa_fin:

/* structure poll see doc linux */
    .struct  0
poll_fd:                            @   File Descriptor
    .struct  poll_fd + 4
poll_events:                        @  events mask
    .struct  poll_events + 4
poll_revents:                       @ events returned
    .struct  poll_revents + 4
poll_fin:
/*********************************/
/* Initialized data              */
/*********************************/
.data
sMessResult:           .ascii " "
sMessValeur:           .fill 11, 1, ' '             @ size => 11
szCarriageReturn:      .asciz "\n"
szMessGameWin:         .ascii "You win in "
sMessCounter:           .fill 11, 1, ' '            @ size => 11
                       .asciz " move number !!!!\n"
szMessMoveError:       .asciz "Huh... Impossible move !!!!\n"
szMessErreur:          .asciz "Error detected.\n"
szMessSpaces:          .asciz "    "
iGraine:               .int 123456
/*************************************************/
szMessErr: .ascii	"Error code hexa : "
sHexa: .space 9,' '
         .ascii "  decimal :  "
sDeci: .space 15,' '
         .asciz "\n"
szClear:     .byte 0x1B
		     .byte 'c'                         @ console clear
		     .byte 0
/*********************************/
/* UnInitialized data            */
/*********************************/
.bss
.align 4
iCodeError:     .skip 4
ibox:          .skip 4 * NBBOX                 @ game boxes
iEnd:           .skip 4                        @ 0 loop  1 = end loop
iTouche:        .skip 4                        @ value key pressed
stOldtio:       .skip term_fin                 @ old terminal state
stCurtio:       .skip term_fin                 @ current terminal state
stSigAction:    .skip sa_fin                   @ area signal structure
stSigAction1:   .skip sa_fin
stPoll1:        .skip poll_fin                 @ area poll structure
stPoll2:        .skip poll_fin
/*********************************/
/*  code section                 */
/*********************************/
.text
.global main
main:                                @ entry of program
    mov r0,#0
    ldr r2,iAdribox
    mov r9,#0                        @ move counter
1:                                   @ loop init boxs
    add r1,r0,#1                     @ box value
    str r1,[r2,r0, lsl #2]           @ store value
    add r0,#1                        @ increment counter
    cmp r0,#NBBOX - 2                @ end ?
    ble 1b
    mov r10,#15                      @ empty box location
    ldr r0,iAdribox
    bl shuffleGame
2:                                   @ loop moves
    ldr r0,iAdribox
    bl displayGame
    //ldr r0,iAdribox
    //bl gameOK                      @ end game ?
    //cmp r0,#1
    //beq 50f
    bl readKey                       @ read key
    cmp r0,#-1
    beq 100f                         @ error or control-c
    mov r1,r0                        @ key
    ldr r0,iAdribox
    bl keyMove
    ldr r0,iAdribox
    bl gameOK                        @ end game ?
    cmp r0,#1
    bne 2b                           @ no -> loop
50:                                  @ win
    mov r0,r9                        @ move counter
    ldr r1,iAdrsMessCounter
    bl conversion10
    ldr r0,iAdrszMessGameWin
    bl affichageMess

100:                                 @ standard end of the program
    mov r0, #0                       @ return code
    mov r7, #EXIT                    @ request to exit program
    svc #0                           @ perform the system call

iAdrsMessValeur:          .int sMessValeur
iAdrszCarriageReturn:     .int szCarriageReturn
iAdrsMessResult:          .int sMessResult
iAdribox:                 .int ibox
iAdrszMessGameWin:        .int szMessGameWin
iAdrsMessCounter:         .int sMessCounter
/******************************************************************/
/*     key move                                                   */
/******************************************************************/
/* r0 contains boxs address           */
/* r1 contains key value               */
/* r9 move counter                     */
/* r10 contains location empty box    */
keyMove:
    push {r1-r8,lr}                  @ save  registers
    mov r8,r0
    cmp r1,#0x42                     @ down arrow
    bne 1f
    cmp r10,#4                       @ if r10 < 4   error
    blt 80f
    sub r2,r10,#4                    @ compute location
    b 90f
1:
    cmp r1,#0x41                     @ high arrow
    bne 2f
    cmp r10,#11                      @ if r10 > 11   error
    bgt 80f
    add r2,r10,#4                    @ compute location
    b 90f
2:
    cmp r1,#0x43                     @ right arrow
    bne 3f
    tst r10,#0b11                    @ if r10 = 0,4,8,12   error
    beq 80f
    sub r2,r10,#1                    @ compute location
    b 90f
3:
    cmp r1,#0x44                     @ left arrow
    bne 100f
    and r3,r10,#0b11                 @ error if r10 = 3 7 11 and 15
    cmp r3,#3
    beq 80f
    add r2,r10,#1                    @ compute location
    b 90f

80:                                  @ move error
    ldr r0,iAdriCodeError
    mov r1,#1
    str r1,[r0]
    b 100f
90:                                  @ white box and move box inversion
    ldr r3,[r8,r2,lsl #2]
    str r3,[r8,r10,lsl #2]
    mov r10,r2
    mov r3,#0
    str r3,[r8,r10,lsl #2]
    add r9,#1                        @ increment move counter
100:
    pop {r1-r8,lr}                   @ restaur registers
    bx lr                            @return
iAdriCodeError:             .int iCodeError
/******************************************************************/
/*     shuffle game                                       */
/******************************************************************/
/* r0 contains boxs address           */
shuffleGame:
    push {r1-r6,lr}                     @ save  registers
    mov r1,r0
    mov r0,#4
    bl genereraleas
    lsl r4,r0,#1
    mov r0,r8
1:
    mov r0,#14
    bl genereraleas
    add r6,r0,#1
    mov r0,#14
    bl genereraleas
    add r5,r0,#1
    ldr r2,[r1,r6,lsl #2]
    ldr r3,[r1,r5,lsl #2]
    str r2,[r1,r5,lsl #2]
    str r3,[r1,r6,lsl #2]
    subs r4,#1
    bgt 1b

100:
    pop {r1-r6,lr}                      @ restaur registers
    bx lr                               @return
/******************************************************************/
/*     game Ok ?                                      */
/******************************************************************/
/* r0 contains boxs address           */
gameOK:
    push {r1-r8,lr}                     @ save  registers
    mov r8,r0
    mov r2,#0
    ldr r3,[r8,r2,lsl #2]
    add r2,#1
1:
    ldr r4,[r8,r2,lsl #2]
    cmp r4,r3
    movlt r0,#0                         @ game mot Ok
    blt 100f
    mov r3,r4
    add r2,#1
    cmp r2,#NBBOX -2
    ble 1b
    mov r0,#1                           @ game Ok

100:
    pop {r1-r8,lr}                      @ restaur registers
    bx lr                               @return
/******************************************************************/
/*     display game                                       */
/******************************************************************/
/* r0 contains boxs address           */
displayGame:
    push {r1-r5,lr}                     @ save  registers
    @ clear !
    mov r4,r0
    ldr r0,iAdrszClear
    bl affichageMess
    mov r2,#0
    ldr r1,iAdrsMessValeur
1:
    ldr r0,[r4,r2,lsl #2]
    cmp r0,#0
    ldreq r0,iSpaces                    @ store spaces
    streq r0,[r1]
    beq 2f
    bl conversion10                     @ call conversion decimal
    mov r0,#0
    strb r0,[r1,#3]                     @ zéro final
2:

    ldr r0,iAdrsMessResult
    bl affichageMess                    @ display message
    add r0,r2,#1
    tst r0,#0b11
    bne 3f
    ldr r0,iAdrszCarriageReturn
    bl affichageMess                    @ display message
3:
    add r2,#1
    cmp r2,#NBBOX - 1
    ble 1b
    ldr r0,iAdrszCarriageReturn
    bl affichageMess                    @ display line return
    ldr r0,iAdriCodeError               @ error detected ?
    ldr r1,[r0]
    cmp r1,#0
    beq 100f
    mov r1,#0                           @ raz error code
    str r1,[r0]
    ldr r0,iAdrszMessMoveError          @ display error message
    bl affichageMess
100:
    pop {r1-r5,lr}                      @ restaur registers
    bx lr                               @return
iSpaces:                       .int 0x00202020       @ spaces
iAdrszClear:                   .int szClear
iAdrszMessMoveError:           .int szMessMoveError
/******************************************************************/
/*     display text with size calculation                         */
/******************************************************************/
/* r0 contains the address of the message */
affichageMess:
    push {r0,r1,r2,r7,lr}                          @ save  registres
    mov r2,#0                                      @ counter length
1:                                                 @ loop length calculation
    ldrb r1,[r0,r2]                                @ read octet start position + index
    cmp r1,#0                                      @ if 0 its over
    addne r2,r2,#1                                 @ else add 1 in the length
    bne 1b                                         @ and loop
                                                   @ so here r2 contains the length of the message
    mov r1,r0                                      @ address message in r1
    mov r0,#STDOUT                                 @ code to write to the standard output Linux
    mov r7, #WRITE                                 @ code call system "write"
    svc #0                                         @ call systeme
    pop {r0,r1,r2,r7,lr}                           @ restaur des  2 registres */
    bx lr                                          @ return
/******************************************************************/
/*     Converting a register to a decimal unsigned                */
/******************************************************************/
/* r0 contains value and r1 address area   */
/* r0 return size of result (no zero final in area) */
/* area size => 11 bytes          */
.equ LGZONECAL,   10
conversion10:
    push {r1-r4,lr}                                 @ save registers
    mov r3,r1
    mov r2,#LGZONECAL
1:                                                  @ start loop
    bl divisionpar10U                               @ unsigned  r0 <- dividende. quotient ->r0 reste -> r1
    add r1,#48                                      @ digit
    strb r1,[r3,r2]                                 @ store digit on area
    cmp r0,#0                                       @ stop if quotient = 0
    subne r2,#1                                     @ else previous position
    bne 1b                                          @ and loop
                                                    @ and move digit from left of area
    mov r4,#0
2:
    ldrb r1,[r3,r2]
    strb r1,[r3,r4]
    add r2,#1
    add r4,#1
    cmp r2,#LGZONECAL
    ble 2b
                                                      @ and move spaces in end on area
    mov r0,r4                                         @ result length
    mov r1,#' '                                       @ space
3:
    strb r1,[r3,r4]                                   @ store space in area
    add r4,#1                                         @ next position
    cmp r4,#LGZONECAL
    ble 3b                                            @ loop if r4 <= area size

100:
    pop {r1-r4,lr}                                    @ restaur registres
    bx lr                                             @return

/***************************************************/
/*   division par 10   unsigned                    */
/***************************************************/
/* r0 dividende   */
/* r0 quotient    */
/* r1 remainder   */
divisionpar10U:
    push {r2,r3,r4, lr}
    mov r4,r0                                          @ save value
    ldr r3,iMagicNumber                                @ r3 <- magic_number    raspberry 1 2
    umull r1, r2, r3, r0                               @ r1<- Lower32Bits(r1*r0) r2<- Upper32Bits(r1*r0)
    mov r0, r2, LSR #3                                 @ r2 <- r2 >> shift 3
    add r2,r0,r0, lsl #2                               @ r2 <- r0 * 5
    sub r1,r4,r2, lsl #1                               @ r1 <- r4 - (r2 * 2)  = r4 - (r0 * 10)
    pop {r2,r3,r4,lr}
    bx lr                                              @ leave function
iMagicNumber:  	.int 0xCCCCCCCD
/***************************************************/
/*   Generation random number                  */
/***************************************************/
/* r0 contains limit  */
genereraleas:
    push {r1-r4,lr}                                    @ save registers
    ldr r4,iAdriGraine
    ldr r2,[r4]
    ldr r3,iNbDep1
    mul r2,r3,r2
    ldr r3,iNbDep1
    add r2,r2,r3
    str r2,[r4]                                        @ maj de la graine pour l appel suivant
    cmp r0,#0
    beq 100f
    mov r1,r0                                          @ divisor
    mov r0,r2                                          @ dividende
    bl division
    mov r0,r3                                          @ résult = remainder

100:                                                   @ end function
    pop {r1-r4,lr}                                     @ restaur registers
    bx lr                                              @ return
/*****************************************************/
iAdriGraine: .int iGraine
iNbDep1: .int 0x343FD
iNbDep2: .int 0x269EC3
/***************************************************/
/* integer division unsigned                       */
/***************************************************/
division:
    /* r0 contains dividend */
    /* r1 contains divisor */
    /* r2 returns quotient */
    /* r3 returns remainder */
    push {r4, lr}
    mov r2, #0                                         @ init quotient
    mov r3, #0                                         @ init remainder
    mov r4, #32                                        @ init counter bits
    b 2f
1:                                                     @ loop
    movs r0, r0, LSL #1                                @ r0 <- r0 << 1 updating cpsr (sets C if 31st bit of r0 was 1)
    adc r3, r3, r3                                     @ r3 <- r3 + r3 + C. This is equivalent to r3 ? (r3 << 1) + C
    cmp r3, r1                                         @ compute r3 - r1 and update cpsr
    subhs r3, r3, r1                                   @ if r3 >= r1 (C=1) then r3 <- r3 - r1
    adc r2, r2, r2                                     @ r2 <- r2 + r2 + C. This is equivalent to r2 <- (r2 << 1) + C
2:
    subs r4, r4, #1                                    @ r4 <- r4 - 1
    bpl 1b                                             @ if r4 >= 0 (N=0) then loop
    pop {r4, lr}
    bx lr
/***************************************************/
/* read touch                                      */
/***************************************************/
readKey:
    push {r1-r7,lr}
    mov r5,#0
    /* read terminal state */
    mov r0,#STDIN                                @ input console
    mov r1,#TCGETS
    ldr r2,iAdrstOldtio
    mov r7, #IOCTL                               @ call system Linux
    svc #0
    cmp r0,#0                                    @ error ?
    beq 1f
    ldr r1,iAdrszMessErreur                      @ error message
    bl   displayError
    mov r0,#-1
    b 100f
1:
    adr r0,sighandler                            @ adresse routine traitement signal
    ldr r1,iAdrstSigAction                       @ adresse structure sigaction
    str r0,[r1,#sa_handler]                      @ maj handler
    mov r0,#SIGINT                               @ signal type
    ldr r1,iAdrstSigAction
    mov r2,#0                                    @ NULL
    mov r7, #SIGACTION                           @ call system
    svc #0
    cmp r0,#0                                    @ error ?
    bne 97f
    mov r0,#SIGQUIT
    ldr r1,iAdrstSigAction
    mov r2,#0                                    @ NULL
    mov r7, #SIGACTION                           @ call system
    svc #0
    cmp r0,#0                                    @ error ?
    bne 97f
    mov r0,#SIGTERM
    ldr r1,iAdrstSigAction
    mov r2,#0                                    @ NULL
    mov r7, #SIGACTION                           @ appel systeme
    svc #0
    cmp r0,#0
    bne 97f
    @
    adr r0,iSIG_IGN                              @ address signal ignore function
    ldr r1,iAdrstSigAction1
    str r0,[r1,#sa_handler]
    mov r0,#SIGTTOU                              @invalidate other process signal
    ldr r1,iAdrstSigAction1
    mov r2,#0                                    @ NULL
    mov r7,#SIGACTION                            @ call system
    svc #0
    cmp r0,#0
    bne 97f
    @
    /* read terminal current state  */
    mov r0,#STDIN
    mov r1,#TCGETS
    ldr r2,iAdrstCurtio                          @ address current termio
    mov r7,#IOCTL                                @ call systeme
    svc #0
    cmp r0,#0                                    @ error ?
    bne 97f
    mov r2,#ICANON | ECHO                        @ no key pressed echo on display
    mvn r2,r2                                    @ and one key
    ldr r1,iAdrstCurtio
    ldr r3,[r1,#term_c_lflag]
    and r3,r2                                    @ add flags
    str r3,[r1,#term_c_lflag]                    @ and store
    mov r0,#STDIN                                @ maj terminal current state
    mov r1,#TCSETS
    ldr r2,iAdrstCurtio
    mov r7, #IOCTL                               @ call system
    svc #0
    cmp r0,#0
    bne 97f
    @
2:                                               @ loop waiting key
    ldr r0,iAdriEnd                              @ if signal ctrl-c  -> end
    ldr r0,[r0]
    cmp r0,#0
    movne r5,#-1
    bne 98f
    ldr r0,iAdrstPoll1                            @ address structure poll
    mov r1,#STDIN
    str r1,[r0,#poll_fd]                          @ maj FD
    mov r1,#POLLIN                                @ action code
    str r1,[r0,#poll_events]
    mov r1,#1                                     @ items number structure poll
    mov r2,#0                                     @ timeout = 0
    mov r7,#SYSPOLL                               @ call system POLL
    svc #0
    cmp r0,#0                                     @ key pressed ?
    ble 2b                                        @ no key pressed -> loop
                                                  @ read key
    mov r0,#STDIN                                 @ File Descriptor
    ldr r1,iAdriTouche                            @ buffer address
    mov r2,#TAILLEBUFFER                          @ buffer size
    mov r7,#READ                                  @ read key
    svc #0
    cmp r0,#0                                     @ error ?
    bgt 98f

97:                                               @ error detected
    ldr r1,iAdrszMessErreur                       @ error message
    bl   displayError
    mov r5,#-1
98:                                               @ end then restaur begin state terminal
    mov r0,#STDIN
    mov r1,#TCSETS
    ldr r2,iAdrstOldtio
    mov r7,#IOCTL                                 @ call system
    svc #0
    cmp r0,#0
    beq 99f                                       @ restaur ok
    ldr r1,iAdrszMessErreur                       @ error message
    bl   displayError
    mov r0,#-1
    b 100f
99:
    cmp r5,#0                                     @ error or control-c
    ldreq r2,iAdriTouche                          @ key address
    ldreqb r0,[r2,#2]                             @ return key byte
    movne r0,r5                                   @ or error
100:
    pop {r1-r7, lr}
    bx lr
iSIG_IGN:                 .int 1
iAdriEnd:                 .int iEnd
iAdrstPoll1:              .int stPoll1
iAdriTouche:              .int iTouche
iAdrstOldtio:             .int stOldtio
iAdrstCurtio:             .int stCurtio
iAdrstSigAction:          .int stSigAction
iAdrstSigAction1:         .int stSigAction1
iAdrszMessErreur :        .int szMessErreur
/******************************************************************/
/*     traitement du signal                                       */
/******************************************************************/
sighandler:
    push {r0,r1}
    ldr r0,iAdriEnd
    mov r1,#1                 @ maj zone end
    str r1,[r0]
    pop {r0,r1}
    bx lr
/***************************************************/
/*   display error message                         */
/***************************************************/
/* r0 contains error code  r1 : message address */
displayError:
    push {r0-r2,lr}                         @ save registers
    mov r2,r0                               @ save error code
    mov r0,r1
    bl affichageMess
    mov r0,r2                               @ error code
    ldr r1,iAdrsHexa
    bl conversion16                         @ conversion hexa
    mov r0,r2                               @ error code
    ldr r1,iAdrsDeci                        @ result address
    bl conversion10                         @ conversion decimale
    ldr r0,iAdrszMessErr                    @ display error message
    bl affichageMess
100:
    pop {r0-r2,lr}                          @ restaur registers
    bx lr                                   @ return
iAdrszMessErr:                 .int szMessErr
iAdrsHexa:                     .int sHexa
iAdrsDeci:                     .int sDeci
/******************************************************************/
/*     Converting a register to hexadecimal                      */
/******************************************************************/
/* r0 contains value and r1 address area   */
conversion16:
    push {r1-r4,lr}                                    @ save registers
    mov r2,#28                                         @ start bit position
    mov r4,#0xF0000000                                 @ mask
    mov r3,r0                                          @ save entry value
1:                                                     @ start loop
    and r0,r3,r4                                       @value register and mask
    lsr r0,r2                                          @ move right
    cmp r0,#10                                         @ compare value
    addlt r0,#48                                       @ <10  ->digit
    addge r0,#55                                       @ >10  ->letter A-F
    strb r0,[r1],#1                                    @ store digit on area and + 1 in area address
    lsr r4,#4                                          @ shift mask 4 positions
    subs r2,#4                                         @  counter bits - 4 <= zero  ?
    bge 1b                                             @  no -> loop

100:
    pop {r1-r4,lr}                                     @ restaur registers
    bx lr                                              @return


Astro

type Puzzle(var items: {}, var position: -1)

fun mainframe(puz):
    let d = puz.items
    print('+-----+-----+-----+-----+')
    print(d[1], d[2], d[3], d[4], first: '|', sep: '|', last: '|')
    print('+-----+-----+-----+-----+')
    print(d[5], d[6], d[7], d[8], first: '|', sep: '|', last: '|')
    print('+-----+-----+-----+-----+')
    print(d[9], d[10], d[11], d[12], first: '|', sep: '|', last: '|')
    print('+-----+-----+-----+-----+')
    print(d[13], d[14], d[15], d[16], first: '|', sep: '|', last: '|')
    print('+-----+-----+-----+-----+')

fun format(puz, ch):
    match ch.trim().length:
        1 => '  $ch  '
        2 => '  $ch '
        0 => '     '

fun change(puz, to):
    let fro = puz.position
    for a, b in puz.items where b == puz.format(str i):
        to = a
        break

    swap(puz.items[fro], :[to])
    puz.position = to;

fun buildboard(puz, difficulty):
    for i in 1..16:
        puz.items[i] = puz.format(str i)

    var tmp = a
    for a, b in puz.items where b == '  16 ':
        puz.items[a] = '     '
            tmp = a
            break

    puz.position = tmp
    let diff = match difficulty:
        0 => 10
        1 => 50
        _ => 100

    for i in 1..diff:
        let lst = puz.validmoves()
        let lst1 = []
        for j in lst:
            lst1.push! j.trim().int()
        puz.change(lst1[random(1, lst1.length - 1)])

fun validmoves(puz):
    match puz.position:
        6 | 7 | 10 | 11 =>
            puz.items[pos - 4], :[pos - 1], :[pos + 1], :[pos + 4]
        5 | 9 =>
            puz.items[pos - 4], :[pos + 4], :[pos + 1]
        8 | 12 =>
            puz.items[pos - 4], :[pos + 4], :[pos - 1]
        2 | 3 =>
            puz.items[pos - 1], :[pos + 1], :[pos + 4]
        14 | 15 =>
            puz.items[pos - 1], :[pos + 1], :[pos - 4]
        1 =>
            puz.items[pos + 1], :[pos + 4]
        4 =>
            puz.items[pos - 1], :[pos + 4]
        13 =>
            puz.items[pos + 1], :[pos - 4]
        16 =>
            puz.items[pos - 1], :[pos - 4]

fun mainframe(puz):
    var flag = false
    for a, b in puz.items:
        if b == '     ':
            pass
        else:
            flag = (a == b.trim().int())
    ..
    return flag

let game = Puzzle()
game.buildboard(
    int(input('Enter the difficulty : 0 1 2\n2 => highest 0=> lowest\n'))
)
game.mainframe()

print 'Enter 0 to exit'

loop:
    print 'Hello user:\nTo change the position just enter the no. near it'

    var lst = game.validmoves()
    var lst1 = []
    for i in lst:
        lst1.push! i.trim().int()
        print(i.strip(), '\t', last: '')

    print()

    let value = int(input())
    if value == 0:
        break
    elif x not in lst1:
        print('Wrong move')
    else:
        game.change(x)

    game.mainframe()
    if g.gameover():
        print 'You WON'
        break

AutoHotkey

Size := 20
Grid := [], Deltas := ["-1,0","1,0","0,-1","0,1"], Width := Size * 2.5
Gui, font, S%Size%
Gui, add, text, y1
loop, 4
{
	Row := A_Index
	loop, 4
	{
		Col := A_Index
		Gui, add, button, % (Col=1 ? "xs y+1" : "x+1 yp") " v" Row "_" Col " w" Width " gButton -TabStop", % Grid[Row,Col] := Col + (Row-1)*4 ; 1-16
	}
}
GuiControl, Hide, % Row "_" Col	; 4_4
Gui, add, Button, % "xs gShuffle w" 4 * Width + 3, Shuffle
Gui, show,, 15 Puzzle
return
;------------------------------
GuiClose:
ExitApp
return
;------------------------------
Shuffle:
Shuffle := true
loop, 1000
{
	Random, Rnd, 1,4
	Move(StrSplit(Deltas[Rnd], ",").1, StrSplit(Deltas[Rnd], ",").2)
}
Shuffle := false
return
;------------------------------
Button:
buttonRow := SubStr(A_GuiControl, 1, 1), ButtonCol := SubStr(A_GuiControl, 3, 1)
if Abs(buttonRow-Row) > 1 || Abs(ButtonCol-Col) > 1 || Abs(buttonRow-Row) = Abs(ButtonCol-Col)
	return
Move(buttonRow-Row, ButtonCol-Col)
return
;------------------------------
#IfWinActive, 15 Puzzle
;------------------------------
Down::
Move(-1, 0)
return
;------------------------------
Up::
Move(1, 0)
return
;------------------------------
Right::
Move(0, -1)
return
;------------------------------
Left::
Move(0, 1)
return
;------------------------------
#IfWinActive
;------------------------------
Move(deltaRow, deltaCol){
	global
	if (Row+deltaRow=0) || (Row+deltaRow=5) || (Col+deltaCol=0) || (Col+deltaCol=5)
		return
	GuiControl, Hide, % Row+deltaRow "_" Col+deltaCol
	GuiControl, Show, % Row "_" Col
	GuiControl,, %Row%_%Col%, % Grid[Row+deltaRow, Col+deltaCol]
	Grid[Row, Col] := Grid[Row+deltaRow, Col+deltaCol]
	Grid[Row+=deltaRow, Col+=deltaCol] := 16
	if Shuffle
		return
	gridCont := ""
	for m, obj in grid
		for n, val in obj
			gridCont .= val ","
	if (Trim(gridCont, ",") = "1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16")
		MsgBox, 262208, 15 Puzzle, You solved 15 Puzzle
}

BASIC

=

Commodore BASIC

=

10 REM 15-PUZZLE GAME
20 REM COMMODORE BASIC 2.0
30 REM ********************************
40 GOSUB 400 : REM INTRO AND LEVEL
50 GOSUB 510 : REM SETUP BOARD
60 GOSUB 210 : REM PRINT PUZZLE
70 PRINT "TO MOVE A PIECE, ENTER ITS NUMBER:"
80 INPUT X
90 GOSUB 760 : REM CHECK IF MOVE IS VALID
100 IF MV=0 THEN PRINT "WRONG MOVE" : GOSUB 1110 : GOTO 60
110 D(Z)=X : D(Y)=0
120 GOSUB 210 : REM PRINT PUZZLE
130 GOSUB 1010: REM CHECK IF PUZZLE COMPLETE
140 IF PC THEN 160
150 GOTO 70
160 PRINT"YOU WON!"
170 END
180 REM
190 REM *******************************
200 REM PRINT/DRAW THE PUZZLE
210 FOR P=1 TO 16
220   IF D(P)=0 THEN D$(P)="     " : GOTO 260
230   S$=STR$(D(P))
240   N=LEN(S$)
250   D$(P) = LEFT$("   ",3-N)+S$+"  "
260 NEXT
270 PRINT "+-----+-----+-----+-----+"
280 PRINT "!"D$(1)"!"D$(2)"!"D$(3)"!"D$(4)"!"
290 PRINT "+-----+-----+-----+-----+"
300 PRINT "!"D$(5)"!"D$(6)"!"D$(7)"!"D$(8)"!"
310 PRINT "+-----+-----+-----+-----+"
320 PRINT "!"D$(9)"!"D$(10)"!"D$(11)"!"D$(12)"!"
330 PRINT "+-----+-----+-----+-----+"
340 PRINT "!"D$(13)"!"D$(14)"!"D$(15)"!"D$(16)"!"
350 PRINT "+-----+-----+-----+-----+"
360 RETURN
370 REM
380 REM *******************************
390 REM INTRO AND LEVEL OF DIFFICULTY
400 PRINT CHR$(147)
410 DIM SH(3) : SH(1)=10 : SH(2)=50 : SH(3)=100
420 PRINT "15 PUZZLE GAME FOR COMMODORE BASIC 2.0" : PRINT : PRINT
430 PRINT "PLEASE ENTER LEVEL OF DIFFICULTY,"
440 PRINT "1(EASY), 2(MEDIUM) OR 3(HARD):";
450 INPUT V
460 IF V<1 OR V>3 THEN 440
470 RETURN
480 REM
490 REM *******************************
500 REM BUILD THE BOARD
510 DIM D(16) : DIM D$(16) : REM BOARD PIECES
520 REM SET PIECES IN CORRECT ORDER FIRST
530 FOR P=1 TO 15
540   D(P) = P
550 NEXT
560 D(16) = 0 : REM 0 = EMPTY PIECE/SLOT
570 Z=16      : REM Z = EMPTY POSITION
580 PRINT: PRINT "SHUFFLING PIECES";
590 FOR N=1 TO SH(V)
600   PRINT".";
610   X = INT(RND(0)*4)+1
620   IF X=1 THEN R=Z-4
630   IF X=2 THEN R=Z+4
640   IF (X=3) AND (INT((Z-1)/4)<>(Z-1)/4) THEN R=Z-1
650   IF (X=4) AND (INT(Z/4)<>Z/4) THEN R=Z+1
660   IF R<1 OR R>16 THEN 610
670   D(Z)=D(R)
680   Z=R
690   D(Z)=0
700 NEXT
710 PRINT CHR$(147)
720 RETURN
730 REM
740 REM *******************************
750 REM CHECK IF MOVE IS VALID
760 MV = 0
770 IF X<1 OR X>15 THEN RETURN
780 REM FIND POSITION OF PIECE X
790 P=1
800 IF D(P)=X THEN 840
810   P=P+1
820   IF P>16 THEN PRINT "UH OH!" : STOP
830 GOTO 800
840 Y=P
850 REM FIND POSITION OF EMPTY PIECE
860 P=1
870 IF D(P)=0 THEN 910
880   P=P+1
890   IF P>16 THEN PRINT "UH OH!" : STOP
900 GOTO 870
910 Z=P
920 REM CHECK IF EMPTY PIECE IS ABOVE, BELOW, LEFT OR RIGHT TO PIECE X
930 IF Y-4=Z THEN MV=1 : RETURN
940 IF Y+4=Z THEN MV=1 : RETURN
950 IF (Y-1=Z) AND (INT(Z/4)<>Z/4) THEN MV=1 : RETURN
960 IF (Y+1=Z) AND (INT(Y/4)<>Y/4) THEN MV=1 : RETURN
970 RETURN
980 REM
990 REM *******************************
1000 REM CHECK IF PUZZLE IS COMPLETE / GAME OVER
1010 PC = 0
1020 P=1
1030 IF (P>=16) OR (D(P)<>P) THEN 1060
1040   P=P+1
1050 GOTO 1030
1060 IF P=16 THEN PC=1
1070 RETURN
1080 REM
1090 REM ******************************
1100 REM A SMALL DELAY
1110 FOR T=0 TO 400
1120 NEXT
1130 RETURN

C

===C89, 22 lines version=== The task, as you can see, can be resolved in 22 lines of no more than 80 characters. Of course, the source code in C is not very readable. The second example works exactly the same way, but it was written in much more human readable way. The program also works correctly for non-standard number of rows and/or columns.

/* RosettaCode: Fifteen puzle game, C89, plain vanillia TTY, MVC, § 22 */
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define N 4
#define M 4
enum Move{UP,DOWN,LEFT,RIGHT};int hR;int hC;int cc[N][M];const int nS=100;int
update(enum Move m){const int dx[]={0,0,-1,1};const int dy[]={-1,1,0,0};int i=hR
+dy[m];int j=hC+dx[m];if(i>= 0&&i<N&&j>=0&&j<M){cc[hR][hC]=cc[i][j];cc[i][j]=0;
hR=i;hC=j;return 1;}return 0;}void setup(void){int i,j,k;for(i=0;i<N;i++)for(j=0
;j<M;j++)cc[i][j]=i*M+j+1;cc[N-1][M-1]=0;hR=N-1;hC=M-1;k=0;while(k<nS)k+=update(
(enum Move)(rand()%4));}int isEnd(void){int i,j; int k=1;for(i=0;i<N;i++)for(j=0
;j<M;j++)if((k<N*M)&&(cc[i][j]!=k++))return 0;return 1;}void show(){int i,j;
putchar('\n');for(i=0;i<N;i++)for(j=0;j<M;j++){if(cc[i][j])printf(j!=M-1?" %2d "
:" %2d \n",cc[i][j]);else printf(j!=M-1?" %2s ":" %2s \n", "");}putchar('\n');}
void disp(char* s){printf("\n%s\n", s);}enum Move get(void){int c;for(;;){printf
("%s","enter u/d/l/r : ");c=getchar();while(getchar()!='\n');switch(c){case 27:
exit(0);case'd':return UP;case'u':return DOWN;case'r':return LEFT;case'l':return
RIGHT;}}}void pause(void){getchar();}int main(void){srand((unsigned)time(NULL));
do setup();while(isEnd());show();while(!isEnd()){update(get());show();}disp(
"You win"); pause();return 0;}

===C89, short version, TTY mode===

/*
 * RosettaCode: Fifteen puzle game, C89, plain vanillia TTY, MVC
 */

#define _CRT_SECURE_NO_WARNINGS /* unlocks printf etc. in MSVC */
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

enum Move { MOVE_UP = 0, MOVE_DOWN = 1, MOVE_LEFT = 2, MOVE_RIGHT = 3 };

/* *****************************************************************************
 * Model
 */

#define NROWS     4
#define NCOLLUMNS 4
int holeRow;
int holeCollumn;
int cells[NROWS][NCOLLUMNS];
const int nShuffles = 100;

int Game_update(enum Move move){
    const int dx[] = {  0,  0, -1, +1 };
    const int dy[] = { -1, +1,  0,  0 };
    int i = holeRow     + dy[move];
    int j = holeCollumn + dx[move];
    if ( i >= 0 && i < NROWS && j >= 0 && j < NCOLLUMNS ){
        cells[holeRow][holeCollumn] = cells[i][j];
        cells[i][j] = 0; holeRow = i; holeCollumn = j;
        return 1;
    }
    return 0;
}

void Game_setup(void){
    int i,j,k;
    for ( i = 0; i < NROWS; i++ )
        for ( j = 0; j < NCOLLUMNS; j++ )
            cells[i][j] = i * NCOLLUMNS + j + 1;
    cells[NROWS-1][NCOLLUMNS-1] = 0;
    holeRow = NROWS - 1;
    holeCollumn = NCOLLUMNS - 1;
    k = 0;
    while ( k < nShuffles )
        k += Game_update((enum Move)(rand() % 4));
}

int Game_isFinished(void){
    int i,j; int k = 1;
    for ( i = 0; i < NROWS; i++ )
        for ( j = 0; j < NCOLLUMNS; j++ )
            if ( (k < NROWS*NCOLLUMNS) && (cells[i][j] != k++ ) )
                return 0;
    return 1;
}


/* *****************************************************************************
 * View
 */

void View_showBoard(){
    int i,j;
    putchar('\n');
    for ( i = 0; i < NROWS; i++ )
        for ( j = 0; j < NCOLLUMNS; j++ ){
            if ( cells[i][j] )
                printf(j != NCOLLUMNS-1 ? " %2d " : " %2d \n", cells[i][j]);
            else
                printf(j != NCOLLUMNS-1 ? " %2s " : " %2s \n", "");
        }
    putchar('\n');
}

void View_displayMessage(char* text){
    printf("\n%s\n", text);
}


/* *****************************************************************************
 * Controller
 */

enum Move Controller_getMove(void){
    int c;
    for(;;){
        printf("%s", "enter u/d/l/r : ");
        c = getchar();
        while( getchar() != '\n' )
            ;
        switch ( c ){
            case 27: exit(EXIT_SUCCESS);
            case 'd' : return MOVE_UP;
            case 'u' : return MOVE_DOWN;
            case 'r' : return MOVE_LEFT;
            case 'l' : return MOVE_RIGHT;
        }
    }
}

void Controller_pause(void){
    getchar();
}

int main(void){

    srand((unsigned)time(NULL));

    do Game_setup(); while ( Game_isFinished() );

    View_showBoard();
    while( !Game_isFinished() ){
        Game_update( Controller_getMove() );
        View_showBoard();
    }

    View_displayMessage("You win");
    Controller_pause();

    return EXIT_SUCCESS;
}


{{Out}}


  9   1   4   7
  6   5   3   2
 13  10       8
 14  15  11  12

enter u/d/l/r : u

  9   1   4   7
  6   5   3   2
 13  10  11   8
 14  15      12

enter u/d/l/r : l

  9   1   4   7
  6   5   3   2
 13  10  11   8
 14  15  12

enter u/d/l/r : d

  9   1   4   7
  6   5   3   2
 13  10  11
 14  15  12   8

enter u/d/l/r :

===C89, long version, TTY/Winapi/ncurses modes===

/**
 * RosettaCode: Fifteen puzle game, C89, MS Windows Console API, MVC
 *
 * @version 0.2 (added TTY and ncurses modes)
 */

#define UNDEFINED_WIN32API_CONSOLE
#define UNDEFINED_NCURSES_CONSOLE
#if !defined (TTY_CONSOLE) && !defined(WIN32API_CONSOLE) && !defined(NCURSES_CONSOLE)
#define TTY_CONSOLE
#endif

#define _CRT_SECURE_NO_WARNINGS    /* enable printf etc. */
#define _CRT_NONSTDC_NO_DEPRECATE  /* POSIX functions enabled */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#if defined(NCURSES_CONSOLE)
#include "curses.h"  /* see http://pdcurses.sourceforge.net/ */
#elif defined(WIN32API_CONSOLE)
#define NOGDI                   /* we don't need GDI */
#define WIN32_LEAN_AND_MEAN     /* we don't need OLE etc. */
#include <windows.h>            /* MS Windows stuff */
#include <conio.h>              /* kbhit() and getch() */
#endif

enum Move { MOVE_UP = 0, MOVE_DOWN = 1, MOVE_LEFT = 2, MOVE_RIGHT = 3 };

/* *****************************************************************************
 * Model
 */

#define NROWS     4
#define NCOLLUMNS 4
int holeRow;
int holeCollumn;
int cells[NROWS][NCOLLUMNS];
const int nShuffles = 100;

int Game_update(enum Move move){
    const int dx[] = {  0,  0, -1, +1 };
    const int dy[] = { -1, +1,  0,  0 };
    int i = holeRow     + dy[move];
    int j = holeCollumn + dx[move];
    if ( i >= 0 && i < NROWS && j >= 0 && j < NCOLLUMNS ){
        cells[holeRow][holeCollumn] = cells[i][j];
        cells[i][j] = 0; holeRow = i; holeCollumn = j;
        return 1;
    }
    return 0;
}

void Game_setup(void){
    int i,j,k;
    for ( i = 0; i < NROWS; i++ )
        for ( j = 0; j < NCOLLUMNS; j++ )
            cells[i][j] = i * NCOLLUMNS + j + 1;
    cells[NROWS-1][NCOLLUMNS-1] = 0;
    holeRow = NROWS - 1;
    holeCollumn = NCOLLUMNS - 1;
    k = 0;
    while ( k < nShuffles )
        k += Game_update((enum Move)(rand() % 4));
}

int Game_isFinished(void){
    int i,j; int k = 1;
    for ( i = 0; i < NROWS; i++ )
        for ( j = 0; j < NCOLLUMNS; j++ )
            if ( (k < NROWS*NCOLLUMNS) && (cells[i][j] != k++ ) )
                return 0;
    return 1;
}


/* *****************************************************************************
 * View
 */

int fieldWidth;
#ifdef WIN32API_CONSOLE
HANDLE hConsole;
CONSOLE_SCREEN_BUFFER_INFO csbi;
#endif

void View_setup_base(void)
{
    int i;
    fieldWidth = 0;
    for ( i = NROWS * NCOLLUMNS - 1; i > 0; i /= 10 )
        fieldWidth++;
}

#if defined(TTY_CONSOLE)

void View_setup(void) {
    View_setup_base();
}

void View_showBoard()
{
    int i,j;
    putchar('\n');
    for ( i = 0; i < NROWS; i++ )
        for ( j = 0; j < NCOLLUMNS; j++ ){
            if ( cells[i][j] )
                printf(j != NCOLLUMNS-1 ? " %*d " : " %*d \n", fieldWidth, cells[i][j]);
            else
                printf(j != NCOLLUMNS-1 ? " %*s " : " %*s \n", fieldWidth, "");
        }
    putchar('\n');
}

void View_displayMessage(char* text)
{
    printf("\n%s\n", text);
}

#elif defined(NCURSES_CONSOLE)

void View_setup(void) {
    View_setup_base();
    initscr();
    clear();
}

void View_showBoard()
{
    int i,j;
    for ( i = 0; i < NROWS; i++ )
        for ( j = 0; j < NCOLLUMNS; j++ ){
            int x = (fieldWidth+1)*j;
            int y = 2*i;
            if ( cells[i][j] ){
                attron(A_REVERSE);
                mvprintw(y,x,"%*d", fieldWidth, cells[i][j]);
            }else{
                attroff(A_REVERSE);
                mvprintw(y,x,"%*s", fieldWidth, " ");
            }
        }
    attrset(A_NORMAL);
}

void View_displayMessage(char* text)
{
    mvprintw(2*NROWS,0, "%s", text);
}

#elif defined(WIN32API_CONSOLE)

void View_setup(void) {
    const COORD coordHome = { 0, 0 };
    CONSOLE_CURSOR_INFO cci;
    DWORD size, nWritten;
    View_setup_base();
    hConsole = GetStdHandle(STD_OUTPUT_HANDLE);
    cci.bVisible = FALSE;
    cci.dwSize = 1;
    SetConsoleCursorInfo(hConsole,&cci);
    GetConsoleScreenBufferInfo(hConsole,&(csbi));
    size = csbi.dwSize.X*csbi.dwSize.Y;
    FillConsoleOutputCharacter(hConsole,' ',size,coordHome,&nWritten);
    FillConsoleOutputAttribute(hConsole,csbi.wAttributes,size,coordHome,&nWritten);

}

void View_showBoard()
{
    int i,j;
    char labelString[32];
    WORD attributes;
    DWORD nWritten;
    for ( i = 0; i < NROWS; i++ )
        for ( j = 0; j < NCOLLUMNS; j++ ){
            COORD coord = { ((SHORT)fieldWidth+1)*j, coord.Y = 2*i };
            if ( cells[i][j] ){
                sprintf(labelString,"%*d", fieldWidth, cells[i][j]);
                attributes = BACKGROUND_BLUE | BACKGROUND_GREEN | BACKGROUND_RED;
            }else{
                sprintf(labelString,"%*s", fieldWidth, " ");
                attributes = csbi.wAttributes;
            }
            WriteConsoleOutputCharacter(hConsole,labelString,fieldWidth,coord,&nWritten);
            FillConsoleOutputAttribute (hConsole,attributes,fieldWidth,coord,&nWritten);
        }
}

void View_displayMessage(char* text)
{
    DWORD nWritten;
    COORD coord = { 0, 2 * NROWS };
    WriteConsoleOutputCharacter(hConsole,text,strlen(text),coord,&nWritten);
}

#endif


/* *****************************************************************************
 * Controller
 */

#if defined(TTY_CONSOLE)

void Controller_setup(void){
}

enum Move Controller_getMove(void){
    int c;
    for(;;){
        printf("%s", "enter u/d/l/r : ");
        c = getchar();
        while( getchar() != '\n' )
            ;
        switch ( c ){
            case 27: exit(EXIT_SUCCESS);
            case 'd' : return MOVE_UP;
            case 'u' : return MOVE_DOWN;
            case 'r' : return MOVE_LEFT;
            case 'l' : return MOVE_RIGHT;
        }
    }
}

void Controller_pause(void)
{
    getchar();
}

#elif defined(NCURSES_CONSOLE)

void Controller_setup(void){
    noecho();
    cbreak();
    curs_set(0);
    keypad(stdscr,TRUE);
}

enum Move Controller_getMove(void){
    for(;;){
        switch ( wgetch(stdscr) ){
            case  27: exit(EXIT_SUCCESS);
            case KEY_DOWN  : return MOVE_UP;
            case KEY_UP    : return MOVE_DOWN;
            case KEY_RIGHT : return MOVE_LEFT;
            case KEY_LEFT  : return MOVE_RIGHT;
            case ERR: /* NOP */;
        }
    }
}

void Controller_pause(void){
    while ( wgetch(stdscr) == ERR )
        ;
}


#elif defined(WIN32API_CONSOLE)

void Controller_setup(void){
}

enum Move Controller_getMove(void){
    for(;;){
        switch ( getch() ){
            case  27: exit(EXIT_SUCCESS);
            case   0:
            case 224: switch ( getch() ){
                case 80 : return MOVE_UP;
                case 72 : return MOVE_DOWN;
                case 77 : return MOVE_LEFT;
                case 75 : return MOVE_RIGHT;
            }
        }
    }
}

void Controller_pause(void){
    while(  kbhit() ) getch();
    while( !kbhit() )   ;
    while(  kbhit() ) getch();
}

#endif


/* *****************************************************************************
 * Main function: create model, view and controller. Run main loop.
 */
int main(void) {

    srand((unsigned)time(NULL));

    do Game_setup(); while ( Game_isFinished() );
    View_setup();
    Controller_setup();

    View_showBoard();
    while( !Game_isFinished() ){
        Game_update( Controller_getMove() );
        View_showBoard();
    }

    View_displayMessage("You win");
    Controller_pause();

    return EXIT_SUCCESS;
}

C#

{{libheader|System.Windows.Forms}} {{libheader|System.Drawing}} {{works with|C sharp|6}}

using System;
using System.Drawing;
using System.Linq;
using System.Windows.Forms;

public class FifteenPuzzle
{
    const int gridSize = 4; //Standard 15 puzzle is 4x4
    const bool evenSized = gridSize % 2 == 0;
    const int blockCount = gridSize * gridSize;
    const int last = blockCount - 1;
    const int buttonSize = 50;
    const int buttonMargin = 3; //default = 3
    const int formEdge = 9;
    static readonly Random rnd = new Random();
    static readonly Font buttonFont = new Font("Arial", 15.75F, FontStyle.Regular, GraphicsUnit.Point, ((byte)(0)));
    readonly Button[] buttons = new Button[blockCount];
    readonly int[] grid = new int[blockCount];
    readonly int[] positionOf = new int[blockCount];
    int moves = 0;
    DateTime start;

    public static void Main(string[] args)
    {
        FifteenPuzzle p = new FifteenPuzzle();
        Form f = p.BuildForm();
        Application.Run(f);
    }

    public FifteenPuzzle()
    {
        for (int i = 0; i < blockCount; i++) {
            grid[i] = i;
            positionOf[i] = i;
        }
    }

    Form BuildForm()
    {
        Button startButton = new Button {
            Font = new Font("Arial", 9.75F, FontStyle.Regular, GraphicsUnit.Point, ((byte)(0))),
            Size = new Size(86, 23),
            Location = new Point(formEdge,
                (buttonSize + buttonMargin * 2) * gridSize + buttonMargin + formEdge),
            Text = "New Game",
            UseVisualStyleBackColor = true
        };
        startButton.Click += (sender, e) => Shuffle();

        int size = buttonSize * gridSize + buttonMargin * gridSize * 2 + formEdge * 2;
        Form form = new Form {
            Text = "Fifteen",
            ClientSize = new Size(width: size, height: size + buttonMargin * 2 + startButton.Height)
        };
        form.SuspendLayout();
        for (int index = 0; index < blockCount; index++) {
            Button button = new Button {
                Font = buttonFont,
                Size = new Size(buttonSize, buttonSize),
                //Margin = new Padding(buttonMargin),
                Text = (index + 1).ToString(),
                UseVisualStyleBackColor = true
            };
            SetLocation(button, index);
            form.Controls.Add(button);
            buttons[index] = button;
            int i = index;
            button.Click += (sender, e) => ButtonClick(i);
        }
        form.Controls.Add(startButton);
        form.ResumeLayout();
        return form;
    }

    void ButtonClick(int i)
    {
        if (buttons[last].Visible) return;
        int target = positionOf[i];
        if (positionOf[i] / gridSize == positionOf[last] / gridSize) {
            while (positionOf[last] < target) {
                Swap(last, grid[positionOf[last] + 1]);
                moves++;
            }
            while (positionOf[last] > target) {
                Swap(last, grid[positionOf[last] - 1]);
                moves++;
            }
        } else if (positionOf[i] % gridSize == positionOf[last] % gridSize) {
            while (positionOf[last] < target) {
                Swap(last, grid[positionOf[last] + gridSize]);
                moves++;
            }
            while (positionOf[last] > target) {
                Swap(last, grid[positionOf[last] - gridSize]);
                moves++;
            }
        }
        if (Solved()) {
            TimeSpan elapsed = DateTime.Now - start;
            elapsed = TimeSpan.FromSeconds(Math.Round(elapsed.TotalSeconds, 0));
            buttons[last].Visible = true;
            MessageBox.Show($"Solved in {moves} moves. Time: {elapsed}");
        }
    }

    bool Solved() => Enumerable.Range(0, blockCount - 1).All(i => positionOf[i] == i);

    static void SetLocation(Button button, int index)
    {
        int row = index / gridSize, column = index % gridSize;
        button.Location = new Point(
            (buttonSize + buttonMargin * 2) * column + buttonMargin + formEdge,
            (buttonSize + buttonMargin * 2) * row + buttonMargin + formEdge);
    }

    void Shuffle()
    {
        for (int i = 0; i < blockCount; i++) {
            int r = rnd.Next(i, blockCount);
            int g = grid[r];
            grid[r] = grid[i];
            grid[i] = g;
        }
        for (int i = 0; i < blockCount; i++) {
            positionOf[grid[i]] = i;
            SetLocation(buttons[grid[i]], i);
        }
        if (!Solvable()) Swap(0, 1); //Swap any 2 blocks

        buttons[last].Visible = false;
        moves = 0;
        start = DateTime.Now;
    }

    bool Solvable()
    {
        bool parity = true;
        for (int i = 0; i < blockCount - 2; i++) {
            for (int j = i + 1; j < blockCount - 1; j++) {
                if (positionOf[j] < positionOf[i]) parity = !parity;
            }
        }
        if (evenSized && positionOf[last] / gridSize % 2 == 0) parity = !parity;
        return parity;
    }

    void Swap(int a, int b)
    {
        Point location = buttons[a].Location;
        buttons[a].Location = buttons[b].Location;
        buttons[b].Location = location;

        int p = positionOf[a];
        positionOf[a] = positionOf[b];
        positionOf[b] = p;

        grid[positionOf[a]] = a;
        grid[positionOf[b]] = b;
    }
}

C++


#include <time.h>
#include <stdlib.h>
#include <vector>
#include <string>
#include <iostream>
class p15 {
public :
    void play() {
        bool p = true;
        std::string a;
        while( p ) {
            createBrd();
            while( !isDone() ) { drawBrd();getMove(); }
            drawBrd();
            std::cout << "\n\nCongratulations!\nPlay again (Y/N)?";
            std::cin >> a; if( a != "Y" && a != "y" ) break;
        }
    }
private:
    void createBrd() {
        int i = 1; std::vector<int> v;
        for( ; i < 16; i++ ) { brd[i - 1] = i; }
        brd[15] = 0; x = y = 3;
        for( i = 0; i < 1000; i++ ) {
            getCandidates( v );
            move( v[rand() % v.size()] );
            v.clear();
        }
    }
    void move( int d ) {
        int t = x + y * 4;
        switch( d ) {
            case 1: y--; break;
            case 2: x++; break;
            case 4: y++; break;
            case 8: x--;
        }
        brd[t] = brd[x + y * 4];
        brd[x + y * 4] = 0;
    }
    void getCandidates( std::vector<int>& v ) {
        if( x < 3 ) v.push_back( 2 ); if( x > 0 ) v.push_back( 8 );
        if( y < 3 ) v.push_back( 4 ); if( y > 0 ) v.push_back( 1 );
    }
    void drawBrd() {
        int r; std::cout << "\n\n";
        for( int y = 0; y < 4; y++ ) {
            std::cout << "+----+----+----+----+\n";
            for( int x = 0; x < 4; x++ ) {
                r = brd[x + y * 4];
                std::cout << "| ";
                if( r < 10 ) std::cout << " ";
                if( !r ) std::cout << "  ";
                else std::cout << r << " ";
            }
            std::cout << "|\n";
        }
        std::cout << "+----+----+----+----+\n";
    }
    void getMove() {
        std::vector<int> v; getCandidates( v );
        std::vector<int> p; getTiles( p, v ); unsigned int i;
        while( true ) {
            std::cout << "\nPossible moves: ";
            for( i = 0; i < p.size(); i++ ) std::cout << p[i] << " ";
            int z; std::cin >> z;
            for( i = 0; i < p.size(); i++ )
                if( z == p[i] ) { move( v[i] ); return; }
        }
    }
    void getTiles( std::vector<int>& p, std::vector<int>& v ) {
        for( unsigned int t = 0; t < v.size(); t++ ) {
            int xx = x, yy = y;
            switch( v[t] ) {
                case 1: yy--; break;
                case 2: xx++; break;
                case 4: yy++; break;
                case 8: xx--;
            }
            p.push_back( brd[xx + yy * 4] );
        }
    }
    bool isDone() {
        for( int i = 0; i < 15; i++ ) {
            if( brd[i] != i + 1 ) return false;
        }
        return true;
    }
    int brd[16], x, y;
};
int main( int argc, char* argv[] ) {
    srand( ( unsigned )time( 0 ) );
    p15 p; p.play(); return 0;
}


+----+----+----+----+
| 11 |  5 | 12 |  3 |
+----+----+----+----+
| 10 |  7 |  6 |  4 |
+----+----+----+----+
| 13 |    |  2 |  1 |
+----+----+----+----+
| 15 | 14 |  8 |  9 |
+----+----+----+----+

Possible moves: 2 13 14 7

COBOL

Tested with GnuCOBOL

SOURCE FORMAT FREE
*> This code is dedicated to the public domain
*> This is GNUCOBOL 2.0
identification division.
program-id. fifteen.
environment division.
configuration section.
repository. function all intrinsic.
data division.
working-storage section.

01  r pic 9.
01  r-empty pic 9.
01  r-to pic 9.
01  r-from pic 9.

01  c pic 9.
01  c-empty pic 9.
01  c-to pic 9.
01  c-from pic 9.

01  display-table.
    03  display-row occurs 4.
        05  display-cell occurs 4 pic 99.

01  tile-number pic 99.
01  tile-flags pic x(16).

01  display-move value spaces.
    03  tile-id pic 99.

01  row-separator pic x(21) value all '.'.
01  column-separator pic x(3) value ' . '.

01  inversions pic 99.
01  current-tile pic 99.

01  winning-display pic x(32) value
        '01020304'
    &   '05060708'
    &   '09101112'
    &   '13141500'.

procedure division.
start-fifteen.
    display 'start fifteen puzzle'
    display '    enter a two-digit tile number and press <enter> to move'
    display '    press <enter> only to exit'

    *> tables with an odd number of inversions are not solvable
    perform initialize-table with test after until inversions = 0
    perform show-table
    accept display-move
    perform until display-move = spaces
        perform move-tile
        perform show-table
        move spaces to display-move
        accept display-move
    end-perform
    stop run
    .
initialize-table.
    compute tile-number = random(seconds-past-midnight) *> seed only
    move spaces to tile-flags
    move 0 to current-tile inversions
    perform varying r from 1 by 1 until r > 4
    after c from 1 by 1 until c > 4
        perform with test after
        until tile-flags(tile-number + 1:1) = space
            compute tile-number = random() * 100
            compute tile-number = mod(tile-number, 16)
        end-perform
        move 'x' to tile-flags(tile-number + 1:1)
        if tile-number > 0 and < current-tile
            add 1 to inversions
        end-if
        move tile-number to display-cell(r,c) current-tile
    end-perform
    compute inversions = mod(inversions,2)
    .
show-table.
    if display-table = winning-display
        display 'winning'
    end-if
    display space row-separator
    perform varying r from 1 by 1 until r > 4
        perform varying c from 1 by 1 until c > 4
            display column-separator with no advancing
            if display-cell(r,c) = 00
                display '  ' with no advancing
                move r to r-empty
                move c to c-empty
            else
                display display-cell(r,c) with no advancing
            end-if
        end-perform
        display column-separator
    end-perform
    display space row-separator
    .
move-tile.
    if not (tile-id numeric and tile-id >= 01 and <= 15)
        display 'invalid tile number'
        exit paragraph
    end-if

    *> find the entered tile-id row and column (r,c)
    perform varying r from 1 by 1 until r > 4
    after c from 1 by 1 until c > 4
        if display-cell(r,c) = tile-id
            exit perform
        end-if
    end-perform

    *> show-table filled (r-empty,c-empty)
    evaluate true
    when r = r-empty
        if c-empty < c
            *> shift left
            perform varying c-to from c-empty by 1 until c-to > c
                compute c-from = c-to + 1
                move display-cell(r-empty,c-from) to display-cell(r-empty,c-to)
            end-perform
        else
           *> shift right
           perform varying c-to from c-empty by -1 until c-to < c
               compute c-from = c-to - 1
               move display-cell(r-empty,c-from) to display-cell(r-empty,c-to)
           end-perform
       end-if
       move 00 to display-cell(r,c)
    when c = c-empty
        if r-empty < r
            *>shift up
            perform varying r-to from r-empty by 1 until r-to > r
                compute r-from = r-to + 1
                move display-cell(r-from,c-empty) to display-cell(r-to,c-empty)
            end-perform
        else
            *> shift down
            perform varying r-to from r-empty by -1 until r-to < r
                compute r-from = r-to - 1
                move display-cell(r-from,c-empty) to display-cell(r-to,c-empty)
            end-perform
        end-if
        move 00 to display-cell(r,c)
    when other
         display 'invalid move'
    end-evaluate
    .
end program fifteen.

{{out}}

prompt$ cobc -xj fifteen.cbl
start fifteen puzzle
    enter a two-digit tile number and press <enter> to move
    press <enter> only to exit
 .....................
 . 05 . 14 . 08 . 12 .
 . 01 . 10 . 03 . 09 .
 . 02 . 15 . 13 . 11 .
 . 06 .    . 07 . 04 .
 .....................

Common Lisp

Credit to this post for help with the inversions-counting function: [http://www.lispforum.com/viewtopic.php?f=2&t=3422]

Run it (after loading the file) with

|15|::main

.

(defpackage :15
  (:use :common-lisp))
(in-package :15)

(defvar +side+ 4)
(defvar +max+ (1- (* +side+ +side+))) ; 15

(defun make-board ()
  (make-array (list +side+ +side+)
              :initial-contents
              (loop :for i :below +side+ :collecting
                 (loop :for j :below +side+ :collecting
                    (mod (1+ (+ j (* i +side+))) (1+ +max+))))))
(defvar *board* (make-board))

(defun shuffle-board (board)
  (loop for i from (array-total-size board) downto 2
     do (rotatef (row-major-aref board (random i))
                 (row-major-aref board (1- i))))
  board)

(defun pb (stream object &rest args)
  (declare (ignorable args))
  (loop for i below (car (array-dimensions object)) do
       (loop for j below (cadr (array-dimensions object)) do
            (let ((cell (aref object i j)))
              (format stream "(~[  ~:;~:*~2d~])" cell)))
       (format stream "~%")))

(defun sortedp (board)
  (declare (ignorable board))
  (loop for i upto +max+
     when (eq (row-major-aref board i) (mod (1+ i) 16)) do
       (return-from sortedp nil))
  t)

(defun inversions (lst)
  (if (or (null lst) (null (cdr lst)))
      0
      (let* ((half (ceiling (/ (length lst) 2)))
             (left-list (subseq lst 0 half))
             (right-list (subseq lst half)))
        (+ (loop for a in left-list
              summing (loop for b in right-list
                         counting (not (< a b))))
           (inversions left-list)
           (inversions right-list)))))

(defun solvablep (board)
  (let ((inv (inversions (loop for i upto +max+ collecting
                              (row-major-aref board i))))
        (row (- +side+ (first (board-position board 0)))))
    (or (and (oddp +side+)
             (evenp inv))
        (and (evenp +side+)
             (evenp row)
             (oddp inv))
        (and (evenp +side+)
             (oddp row)
             (evenp inv)))))

(defun board-position (board dig)
  (loop for i below (car (array-dimensions board)) do
       (loop for j below (cadr (array-dimensions board))
          when (eq dig (aref board i j)) do
          (return-from board-position (list i j)))))

(defun in-bounds (y x)
  (and (< -1 y +side+)
       (< -1 x +side+)))

(defun get-adjacents (board pos)
  (let ((adjacents ()) (y (first pos)) (x (second pos)))
    (if (in-bounds y (1+ x))
        (push (aref board y (1+ x)) adjacents))
    (if (in-bounds (1+ y) x)
        (push (aref board (1+ y) x) adjacents))
    (if (in-bounds y (1- x))
        (push (aref board y (1- x)) adjacents))
    (if (in-bounds (1- y) x)
        (push (aref board (1- y) x) adjacents))
    adjacents))

(defun main (&rest argv)
  (declare (ignorable argv))
  (setf *random-state* (make-random-state t))
  (loop until (solvablep *board*) do
       (shuffle-board *board*))
  (loop until (sortedp *board*) do
       (format t "~/15:pb/~%" *board*)
       (format t "Which number do you want to swap the blank with?~%> ")
       (let* ((in (read))
              (zpos (board-position *board* 0))
              (pos (board-position *board* in))
              (adj (get-adjacents *board* zpos)))
         (if (find in adj)
             (rotatef (aref *board* (first pos) (second pos))
                      (aref *board* (first zpos) (second zpos))))))
  (format t "You win!~%"))

EasyLang

[https://easylang.online/apps/15-puzzle.html Run it]

len f[] 16 subr initvars time0# = time done = 0 . func draw . . color 432 move 0 0 rect 100 100 for i range 16 h = f[i] if h < 16 x = i mod 4 * 24 + 3 y = i / 4 * 24 + 3 color 210 move x y rect 22 22 move x + 4 y + 5 if h < 10 move x + 6 y + 5 . color 885 text h . . . func init . . call initvars for i range 16 f[i] = i + 1 .

shuffle

for i = 14 downto 1 r = random (i + 1) swap f[r] f[i] .

make it solvable

inv = 0 for i range 15 for j range i if f[j] > f[i] inv += 1 . . . if inv mod 2 <> 0 swap f[0] f[1] . textsize 12 call draw . func move_tile . . c = floor (mouse_x / 25) r = floor (mouse_y / 25) i = r * 4 + c if c > 0 and f[i - 1] = 16 swap f[i] f[i - 1] elif r > 0 and f[i - 4] = 16 swap f[i] f[i - 4] elif r < 3 and f[i + 4] = 16 swap f[i] f[i + 4] elif c < 3 and f[i + 1] = 16 swap f[i] f[i + 1] . call draw done = 1 for i range 15 if f[i] > f[i + 1] done = 0 . . if done = 1 color 432 move 0 0 rect 100 50 textsize 10 color 885 move 5 10 text "Well done!" move 5 25 text "Time: " & floor (time - time0# + 0.5) . . on mouse_down if done = 1 call init else call move_tile . . call init




## Forth


{{trans|C}}
{{works with|gforth|0.7.3}}

Modified to use ANSI escape sequences and Vim's h/j/k/l for input. Caps lock isn't interfering in this version. Also added <tt>q</tt> for quit.


```forth
\ in Forth, you do many things on your own. This word is used to define 2D arrays
: 2D-ARRAY ( height width )
	CREATE DUP ,
	* CELLS ALLOT
	DOES> ( y x baseaddress )
		ROT    ( x baseaddress y )
		OVER @ ( x baseaddress y width )
		*      ( x baseaddress y*width )
		ROT    ( baseaddress y*width x )
		+ 1+ CELLS +
;

require random.fs

HERE SEED !

0 CONSTANT MOVE-UP
1 CONSTANT MOVE-DOWN
2 CONSTANT MOVE-LEFT
3 CONSTANT MOVE-RIGHT

4 CONSTANT NROWS
4 CONSTANT NCOLS
NROWS NCOLS * CONSTANT BOARDSIZE

NROWS 1- CONSTANT Y-MAX
NCOLS 1- CONSTANT X-MAX

1000 CONSTANT NSHUFFLES

CREATE HOLE-X CELL ALLOT
CREATE HOLE-Y CELL ALLOT
NROWS NCOLS 2D-ARRAY BOARD

: DIE-MOVECONST ." Unknown move constant:" . BYE ;
: ESC #ESC EMIT ;
: CLS
	ESC ." [2J"
	ESC ." [H"
;

: NEW-HOLE-POS ( move -- new-y new-x )
	CASE
		MOVE-UP    OF HOLE-Y @ 1- HOLE-X @ ENDOF
		MOVE-DOWN  OF HOLE-Y @ 1+ HOLE-X @ ENDOF
		MOVE-LEFT  OF HOLE-Y @ HOLE-X @ 1- ENDOF
		MOVE-RIGHT OF HOLE-Y @ HOLE-X @ 1+ ENDOF
		DIE-MOVECONST
	ENDCASE
;

: MOVE-VALID? ( move -- valid? )
	CASE
		MOVE-UP    OF HOLE-Y @ 0> ENDOF
		MOVE-DOWN  OF HOLE-Y @ Y-MAX < ENDOF
		MOVE-LEFT  OF HOLE-X @ 0> ENDOF
		MOVE-RIGHT OF HOLE-X @ X-MAX < ENDOF
		DIE-MOVECONST
	ENDCASE
;

: GAME-UPDATE ( move -- success? )
	DUP MOVE-VALID? INVERT IF DROP FALSE EXIT THEN
	NEW-HOLE-POS ( new-y new-x )
	2DUP BOARD @ HOLE-Y @ HOLE-X @ BOARD !
	2DUP BOARD 0 SWAP !
	HOLE-X ! HOLE-Y ! TRUE
;

: INIT-DESIRED-NUM ( y x -- num )
	SWAP NROWS * + 1+ DUP BOARDSIZE = IF DROP 0 THEN
;

: RESET-BOARD ( -- )
	NROWS 0 ?DO
		NCOLS 0 ?DO
			J I INIT-DESIRED-NUM J I BOARD !
		LOOP
	LOOP
;

: GAME-SETUP ( -- )
	RESET-BOARD
	Y-MAX HOLE-Y !
	X-MAX HOLE-X !
	NSHUFFLES 0 ?DO
		BEGIN
			4 RANDOM GAME-UPDATE
		UNTIL
	LOOP
;

: GAME-FINISHED? ( -- finished? )
	0
	NROWS 0 ?DO
		NCOLS 0 ?DO
			J I INIT-DESIRED-NUM J I BOARD @ = IF
				1+
			THEN
		LOOP
	LOOP
	BOARDSIZE =
;

: SHOW-BOARD ( -- )
	CLS CR
	NROWS 0 ?DO
		NCOLS 0 ?DO
			J I BOARD @ DUP 0<> IF
				SPACE 2 U.R SPACE
			ELSE
				DROP 4 SPACES
			THEN
		LOOP
		CR
	LOOP
	CR
;

: GET-MOVE ( -- move )
	BEGIN
		KEY CASE
			#EOF OF BYE ENDOF
			#ESC OF BYE ENDOF
			[CHAR] q OF BYE ENDOF
			[CHAR] Q OF BYE ENDOF
			[CHAR] k OF MOVE-UP TRUE ENDOF
			[CHAR] K OF MOVE-UP TRUE ENDOF
			[CHAR] j OF MOVE-DOWN TRUE ENDOF
			[CHAR] J OF MOVE-DOWN TRUE ENDOF
			[CHAR] h OF MOVE-LEFT TRUE ENDOF
			[CHAR] H OF MOVE-LEFT TRUE ENDOF
			[CHAR] l OF MOVE-RIGHT TRUE ENDOF
			[CHAR] L OF MOVE-RIGHT TRUE ENDOF
			FALSE SWAP
		ENDCASE
	UNTIL
;

: PLAY ( -- )
	GAME-SETUP
	SHOW-BOARD
	BEGIN GAME-FINISHED? INVERT WHILE
		GET-MOVE GAME-UPDATE SHOW-BOARD
	REPEAT
	." You win!" CR
;

PLAY BYE

Fortran

The initial version had me so enamoured by the notion of consecutive cells for the solution having the number of their index as their value (as in CELL(0) = 0 (the blank square), CELL(1) = 1, ... CELL(15) = 15) and the prospect of the check for this being simple, that I failed to perceive that the nice big diagram of the board shown at the head of the article in fact clearly shows the solution state having the blank cell at the ''end'', not the start. Once again it is demonstrated that what you see is ... influenced ... by what you would like to see. After that diversion, the cells shall now be numbered one to sixteen, not zero to fifteen, and so there is no need for the ability introduced by F90 whereby arrays can have a lower bound other than one.

The plan is to use parameters for the board size, which need not be square. As often with Fortran, messing with arrays is the key, though not without opportunities for confusion. Because Fortran stores arrays in column-major order, the arrays are accessed as BOARD(column,row) even though the arrangement is treated as rows down the page and columns across as is usual. By this means, consecutive elements in storage of array BOARD(c,r) are such that the same storage accessed via array BORED(i) thanks to EQUIVALENCE(BOARD,BORED) indexes them as consecutive elements, and so the test that the values are in consecutive order becomes delightfully simple, though alas there is no equivalent of the ''iota'' function of APL whereby the test could be ALL(BORED(1:N - 1) .EQ. IOTA(N - 1))

Column-major ordering also applies to array WAY, which lists the offsets needed to locate squares deemed adjacent to a given location, such as that of the blank square, located by LOCI = LOCZ + WAY(i). Adjacent LOCI are checked for being in range, and if so, added to the list in array LOCM with the moveable piece identified in array MOVE.

It transpires that the F90 compiler will not allow a PARAMETER statement to define values for items appearing in an EQUIVALENCE statement; so much for an attempt to do so in a systematic manner employing related names.

The game plan is to start with an ordered array so that each cell definitely has a unique code, then jumble them via "random" swaps. Possible arrangements turn out to have either odd or even parity based on the number of out-of-sequence squares, and as the allowed transformations do not change the parity and the solution state has even parity, odd parity starting states should not be presented except by those following Franz Kafka. The calculation is simplified by always having the blank square in the last position, thus in the last row. Once an even-parity starting state is floundered upon, the blank square is re-positioned using allowable moves so that the parity is not altered thereby. Then the game begins: single-square moves only are considered, though in practice groups of squares could be moved horizontally or vertically rather than one-step-at-a-time - a possible extension.

The source style uses F90 for its array arithmetic abilities, especially the functions ALL, ANY and COUNT. A statement

LOCZ = MINLOC(BOARD)	!Find the zero. 0 = BOARD(LOCZ(1),LOCZ(2)) == BOARD(ZC,ZR)

could be used but is unnecessary thanks to tricks with EQUIVALENCE. For earlier Fortran, various explicit DO-loops would have to be used. This would at least make clear whether or not the equivalents of ANY and ALL terminated on the first failure or doggedly scanned the entire array no matter what.

      SUBROUTINE SWAP(I,J)	!Alas, furrytran does not provide this.
       INTEGER I,J,T		!So, we're stuck with supplying the obvious.
        T = I			!And, only for one type at a go.
        I = J			!One could define a MODULE containing a collection
        J = T			!And thence a "generic" routine,
      END SUBROUTINE SWAP	!But this will do for now.

      SUBROUTINE SHOW(NR,NC,BOARD)	!The layout won't work for NC > 99...
       INTEGER NR,NC		!Number of rows and columns.
       INTEGER BOARD(NC,NR)	!The board is stored transposed!
       INTEGER I		!A stepper.
       COMMON/IODEV/ MSG	!I talk to the trees...
        WRITE (MSG,1) (I,I = 1,NC)	!Prepare a heading.
    1   FORMAT ("Row|",9("__",I1,:),90("_",I2,:))	!This should suffice.
        DO I = 1,NR		!Chug down the rows.
          WRITE (MSG,2) I,BOARD(1:NC,I)	!The columns of the row. Usage is BOARD(column,row).
    2     FORMAT (I3,"|",99I3)	!Could use parameters, but enough.
        END DO			!On to the next row.
      END SUBROUTINE SHOW	!That was nice.

      PROGRAM PUZZLE
      INTEGER LOCN(2),NR,NC,N	!Describes the shape of the board.
      INTEGER LOCZ(2),ZC,ZR	!Fingers the location of the "blank" square.
      INTEGER LOCI(2),IC,IR	!Fingers a location.
Can't EQUIVALENCE (LOCN(1),NC),(LOCN(2),NR)	!This usage and a PARAMETER statement is too scary.
      EQUIVALENCE (LOCZ(1),ZC),(LOCZ(2),ZR)	!Annotate my (column,row) usage.
      EQUIVALENCE (LOCI(1),IC),(LOCI(2),IR)	!Rather than the displayed (row,column) style.
      PARAMETER (NR = 4, NC = 4, N = NR*NC)	!Determine the shape of the board.
      INTEGER BOARD(NC,NR)		!Thus transpose furrytran's column-major usage. Beware!!!
      INTEGER BORED(N)			!This allows for consecutive comparisons.
      EQUIVALENCE (BOARD,BORED)		!Because the arrays are in the same place.
      INTEGER WAYS			!Now define adjacency.
      PARAMETER (WAYS = 4)		!Just orthogonal neghbours.
      INTEGER WAY(2,WAYS)		!Now list the allowed adjacencies.
      PARAMETER (WAY = (/1,0, 0,1, -1,0, 0,-1/))	!W(1,1), W(2,1), W(1,2), W(2,2), W(1,3), ...
      INTEGER M,MOVE(WAYS),LOCM(2,WAYS)	!Move possibilities.
      INTEGER SPACE			!Document the empty square's code number.
      PARAMETER (SPACE = 0)		!Zero will do.
      INTEGER I,IT,PARITY,TRY		!Odds and ends.
      REAL VALUE			!Humph. Yet another interface to a "random" number generator.
      COMMON/IODEV/ MSG,KBD	!Pass the word.

      KBD = 5	!Standard input. (Keyboard -> Display screen)
      MSG = 6	!Standard output. (Display screen)
      WRITE (MSG,1) NR,NC	!Announce.
    1 FORMAT ("To play 'slide-square' with ",I0," rows and ",
     1 I0," columns.",/,"The game is to slide a square into the space",/
     2 "(thus leaving a space behind) until you attain"/
     3 "the nice orderly layout as follows:",/)
Concoct a board layout.
   10 FOR ALL (I = 1:N - 1) BORED(I) = I	!Prepare the board. Definitely unique values.
      BORED(N) = SPACE	        !The empty square is not at the start! Oh well.
      CALL SHOW(NR,NC,BOARD)	!Reveal the nice layout.
   11 DO I = 1,N - 1		!Now shuffle the squares a bit.
        CALL RANDOM(VALUE)		!0 <= VALUE < 1.
        IT = VALUE*(N - 1) + 1		!1 <= IT < N. Don't round up!
        IF (I.NE.IT) CALL SWAP(BORED(I),BORED(IT))	!Whee!
      END DO			!On to the next victim, leaving the last cell alone.
Calculate the parity, knowing the space is at the end. The target state has even parity, with zero inversions.
      PARITY = 0	!There are two classes of arrangements, that can't mix.
      DO I = 1,N - 2	!Skipping the blank cell still at BORED(N).
        PARITY = PARITY + COUNT(BORED(I) > BORED(I + 1:N - 1))	!For each square,
      END DO		!Count the inversions following.
      IF (MOD(PARITY,2).NE.0) GO TO 11	!No transition can change the parity, so, try for another arrangement.
Choose a new position for the space. Using approved moves will not change the parity.
      CALL RANDOM(VALUE)		!0 <= VALUE < 1.
      ZC = VALUE*(NC - 2) + 1		!1 <= ZC < NC: Choose a random column other than the last.
      BOARD(ZC + 1:NC,NR) = BOARD(ZC:NC - 1,NR)	!Shift the end of the last row back one place.
      BOARD(ZC,NR) = SPACE			!Put the space in the hole.
      CALL RANDOM(VALUE)			!So the parity doesn't change.
      ZR = VALUE*(NR - 2) + 1		!1 <= ZR < NR: Choose a random row, other than the last.
      BOARD(ZC,ZR + 1:NR) = BOARD(ZC,ZR:NR - 1)	!Shift the end of column ZC up one.
      BOARD(ZC,ZR) = SPACE			!Revive the space again.
Cast forth the starting position.
      WRITE (MSG,12)		!Announce the result.
   12 FORMAT (/,"But, your board looks like this...")	!Alas. Almost certainly not in order.
      CALL SHOW(NR,NC,BOARD)	!Just so.
      TRY = 0		!No moves made yet.

Consider possible moves.
   20 TRY = TRY + 1	!Here we go again.
      M = 0		!No moveable pieces are known.
      DO I = 1,WAYS	!So scan the possible ways away from LOCZ.
        LOCI = LOCZ + WAY(1:2,I)	!Finger an adjacent location, via the adjacency offsets in array WAY.
        IF (ALL(LOCI > 0) .AND. ALL(LOCI <= (/NC,NR/))) THEN	!Within bounds?
          M = M + 1			!Yes. We have a candidate.
          MOVE(M) = BOARD(IC,IR)	!Record the piece's name.
          LOCM(:,M) = LOCI		!And, remember where it is...
        END IF			!So much for that location.
      END DO		!Try another offset.
   21 WRITE (MSG,22,ADVANCE="no") MOVE(1:M)	!Two-stage output.
   22 FORMAT ("Moveable pieces: ",<WAYS>(I0:","))	!Since M is not necessarily WAYS, a trailing $ may not be reached..
      WRITE (MSG,23)		!Now for the question. Always at least two moveable squares.
   23 FORMAT(". Choose one: ",$)	!Continue the line, presuming screen and keyboard->screen.
      READ (KBD,*) IT		!Now request the answer. Rather doggedly: blank lines won't do.
      DO I = M,1,-1		!There are at least two possible moves.
        IF (MOVE(I) .EQ. IT) EXIT	!Perhaps this piece was selected.
      END DO			!The INDEX function is alas, only for CHARACTER variables. Grr.
      IF (I .LE. 0) THEN	!I'm suspicious.
        WRITE (MSG,*) "Huh? That is not a moveable piece!"	!Justified!
        IF (IT.GT.0) GO TO 21		!Try again.
        STOP "Oh well."			!Or quit, on negative vibrations.
      END IF			!So much for selecting a piece.
Complete the selected move.
   30 BOARD(ZC,ZR) = IT		!Place the named piece where the space was.
      LOCZ = LOCM(:,I)		!The space is now where that piece came from.
      BOARD(ZC,ZR) = SPACE		!And now holds a space.
c      write (6,*)
c     1 "disorder=",COUNT(BORED(1:N - 2) + 1 .NE. BORED(2:N - 1))
      IF (TRY.LE.6) WRITE (MSG,31)	!Set off with a nice heading.
   31 FORMAT (/"The new layout...")	!Just for clarity.
      CALL SHOW(NR,NC,BOARD)		!Perhaps it will be good.
Check for success.
      IF (BORED(N).NE.SPACE) GO TO 20	!Is the space at the end?
      IF (ANY(BORED(1:N - 2) + 1 .NE. BORED(2:N - 1))) GO TO 20	!Are we there yet?
      WRITE (MSG,*) TRY,"Steps to success!"	!Yes!
      END	!That was fun.

Output: Not so good. As ever, the character cell sizes are not square so a square game board comes out as a rectangle. Similarly, underlining is unavailable (no overprints!) so the layout is not pleasing. There are special "box-drawing" glyphs available, but they are not standardised and there is still no overprinting so that a flabby waste of space results. Further, there is no ability to re-write the display, even though one could easily regard the output to the screen as a random-access file: WRITE (MSG,REC = 6) STUFF would rewrite the sixth line of the display. Instead, output relentlessly rolls forwards, starting as follows:


To play 'slide-square' with 4 rows and 4 columns.
The game is to slide a square into the space
(thus leaving a space behind) until you attain
the nice orderly layout as follows:

Row|__1__2__3__4
  1|  1  2  3  4
  2|  5  6  7  8
  3|  9 10 11 12
  4| 13 14 15  0

But, your board looks like this...
Row|__1__2__3__4
  1| 15  0 14 11
  2|  8 13  5  3
  3|  4  1  7  9
  4| 10  6  2 12
Moveable pieces: 14,13,15. Choose one: 15

The new layout...
Row|__1__2__3__4
  1|  0 15 14 11
  2|  8 13  5  3
  3|  4  1  7  9
  4| 10  6  2 12
Moveable pieces: 15,8. Choose one:

The display here turns out to be less rectangular than that of the "console" screen's usual setting, which changes with the typeface and sizing anyway. Endless variation. As for playing the game, it is much easier to get a "feel" for the possibilities when manipulating the actual physical object. The digital world is less real.

Gambas

'Charlie Ogier (C) 15PuzzleGame 24/04/2017 V0.1.0 Licenced under MIT
'Inspiration came from: -
''http://rosettacode.org/wiki/15_Puzzle_Game
''Bugs or comments to bugs@cogier.com
'Written in Gambas 3.9.2 - Updated on the Gambas Farm 01/05/2017
'Updated so that the message and the Title show the same amount of moves 01/06/2017
'Form now expandable. Font height automated. Form size and position saved 06/06/2107

'Simulate playing the 15 - game(puzzle)         Yes in GUI
'Generate a random start position               Yes
'Prompt the user for which piece To move        No
'Validate if the move is legal(possible)        Yes
'Display the game(puzzle) as pieces are moved   Yes in GUI
'Announce when the puzzle is solved             Yes
'Possibly keep track of the number of moves     Yes

byPos As New Byte[]                                             'Stores the position of the 'Tiles'
siMoves As Short                                                'Stores the amount of moves
hTimer As Timer                                                 'Timer
dTimerStart As Date                                             'Stores the start time
dTimerDiff As Date                                              'Stores the time from the start to now
bTimerOn As Boolean                                             'To know if the Timer is running

Public Sub Form_Open()                                          'Form opens

Settings.read(Me, "Window")                                     'Get details of the last window position and size
With Me                                                         'With the Form..
  .Padding = 5                                                  'Pad the edges
  .Arrangement = Arrange.Row                                    'Arrange the Form
  .Title = "15PuzzleGame v0.3.0"                                'Set the Form Title
End With

BuildForm                                                       'Go to the BuildForm routine

End

Public Sub BuildForm()                                          'To add items to the Form
Dim hButton As Button                                           'We need some Buttons
Dim byRand, byTest As Byte                                      'Various variables
Dim bOK As Boolean                                              'Used to stop duplicate numbers being added
Dim bSolvable As Boolean

Repeat                                                          'Repeat until the puzzle is solvable
  Do                                                            'Start of a Do loop to create 0 to 15 in random order
    byRand = Rand(0, 15)                                        'Get a random number between 0 and 15
    If byRand = 0 Then byRand = 99                              'Change 0 to 99 for the Blank space
    bOK = True                                                  'Set bOK to True
    For Each byTest In byPos                                    'For each number stored in the array byPos
      If byRand = byTest Then bOK = False                       'Check to see if it already exists, if it does set bOK to False
    Next
    If bOK Then byPos.Add(byRand)                               'If not a duplicate then add it to the array
    If byPos.max = 15 Then Break                                'Once the array has 16 numbers get out of here. 99 is used for the blank space
  Loop
  bSolvable = IsItSolvable()                                    'Go to the 'check if puzzle is solvable' routine
  If Not bSolvable Then byPos.clear                             'If it's not solvable then clear byPos
Until bSolvable = True                                          'Repeat until the puzzle is solvable

For byRand = 0 To 15                                            'Loop
  If byPos[byRand] = 99 Then                                    'Check if value is 99 as this is where the blank space will go
    AddPanel                                                    'Go to the AddPanel routine to add the blank space
    Continue                                                    'Skip to the end of the loop
  Endif
  hButton = New Button(Me) As "AllButtons"                      'Add a new button to the Form, all buttons grouped as 'AllButtons'
  With hButton                                                  'With the following properties
    .Text = Str(byPos[byRand])                                  'Add Button text
    .Tag = Str(byPos[byRand])                                   'Add a Tag
    .Height = (Me.Height - 10) / 4                              'Set the Button height
    .Width = (Me.Width - 10) / 4                                'Set the Button width
    .Font.Bold = True                                           'Set the font to Bold
    .Font.Size = 16                                             'Set Font size
  End With
Next

AddTimer                                                        'Go to the AddTimer routine

End


Public Sub AddPanel()                                           'Routine to add an invisible panel that is the blank area
Dim hPanel As Panel                                             'We need a Panel

HPanel = New Panel(Me)                                          'Add the Panel to the Form
With HPanel                                                     'With the following Properties
  .Tag = 99                                                     'Set a Tag to 99
  .Height = (Me.Height - 10) / 4                                'Set the height
  .Width = (Me.Width - 10) / 4                                  'Set the width
End With

End

Public Sub AddTimer()                                           'To add a Timer

hTimer = New Timer As "MyTimer"                                 'Add a Timer
hTimer.Delay = 1000                                             'Set the timer delay

End

Public Sub MyTimer_Timer()                                      'Timer

Me.Title = siMoves & " Moves "                                  'Set the Form Title to show the amount of moves taken

If dTimerStart Then                                             'If a start time has been set then
  dTimerDiff = Time(Now) - dTimerStart                          'Calculate the time difference between StartTime and Now
  Me.Title &= " - " & Str(dTimerDiff)                           'Add the time taken to the Form Title
End If

End

Public Sub AllButtons_Click()                                   'What to do when a Button is clicked
Dim byLast As Byte = Last.Tag                                   'Get the Tag of the Button clicked
Dim byTemp, byCount As Byte                                     'Various variables
Dim byCheck As Byte[] = [88, 88, 88, 88]                        'Used for checking for the blank space
Dim byWChgeck As New Byte[16, 4]
Dim oObj As Object                                              'We need to enumerate Objects

For Each oObj In Me.Children                                    'For each Object (Buttons in this case) that are Children of the Form..
  If oObj.Tag = byLast Then Break                               'If the Tag of the Button matches then we know the position of the Button on the form so get out of here
  Inc byCount                                                   'Increase the value of byCount
Next

Select Case byCount                                             'Depending on the position of the Button
  Case 0                                                        'e.g 0 then we need to check positions 1 & 4 for the blank
    byCheck[0] = 1
    byCheck[1] = 4
  Case 1
    byCheck[0] = 0
    byCheck[1] = 2
    byCheck[2] = 5
  Case 2
    byCheck[0] = 1
    byCheck[1] = 3
    byCheck[2] = 6
  Case 3
    byCheck[0] = 2
    byCheck[1] = 7
  Case 4
    byCheck[0] = 0
    byCheck[1] = 5
    byCheck[2] = 8
  Case 5                                                        'e.g 5 then we need to check positions 1, 4, 6 & 9 for the blank
    byCheck[0] = 1
    byCheck[1] = 4
    byCheck[2] = 6
    byCheck[3] = 9
  Case 6
    byCheck[0] = 2
    byCheck[1] = 5
    byCheck[2] = 7
    byCheck[3] = 10
  Case 7
    byCheck[0] = 3
    byCheck[1] = 6
    byCheck[2] = 11
  Case 8
    byCheck[0] = 4
    byCheck[1] = 9
    byCheck[2] = 12
  Case 9
    byCheck[0] = 5
    byCheck[1] = 8
    byCheck[2] = 10
    byCheck[3] = 13
  Case 10
    byCheck[0] = 6
    byCheck[1] = 9
    byCheck[2] = 11
    byCheck[3] = 14
  Case 11
    byCheck[0] = 7
    byCheck[1] = 10
    byCheck[2] = 15
  Case 12
    byCheck[0] = 8
    byCheck[1] = 13
  Case 13
    byCheck[0] = 9
    byCheck[1] = 12
    byCheck[2] = 14
  Case 14
    byCheck[0] = 10
    byCheck[1] = 13
    byCheck[2] = 15
  Case 15
    byCheck[0] = 11
    byCheck[1] = 14
End Select

For Each byTemp In byCheck                                      'For each value in byCheck
  If byTemp = 88 Then Break                                     'If byTemp = 88 then get out of here
  If byPos[byTemp] = 99 Then                                    'If the position checked is 99 (the blank) then..
    byPos[byTemp] = Last.Text                                   'Set the new position of the Tile in byPos
    byPos[byCount] = 99                                         'Set the existing Tile position to = 99 (blank)
    Inc siMoves                                                 'Inc the amount of moves made
    If Not bTimerOn Then                                        'If the Timer is now needed then
      dTimerStart = Time(Now)                                   'Set the Start time to NOW
      hTimer.start                                              'Start the Timer
      bTimerOn = True                                           'Set bTimerOn to True
    Endif
    Break                                                       'Get out of here
  End If
Next

RebuildForm                                                     'Go to the RebuilForm routine
CheckIfPuzzleCompleted                                          'Check to see if the puzzle has been solved

End

Public Sub CheckIfPuzzleCompleted()                             'Is the puzzle is complete
Dim byTest As Byte[] = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 99] 'byPos will equal this if it is completed
Dim siCount As Short                                            'Counter
Dim bCompleted As Boolean = True                                'Completed?
Dim sMessage As String                                          'String to store the display message

For siCount = 0 To 15                                           'Loop through the byPos
  If byPos[siCount] <> byTest[siCount] Then                     'If the position does not match the completed position then..
    bCompleted = False                                          'Set bCompleted to False
    Break                                                       'Get out of here
  Endif
Next

If bCompleted Then                                              'If the puzzle is completed then
  hTimer.Stop                                                   'Stop the timer
  Me.Title = siMoves & " Moves "                                'Set the Form Title to show the amount of moves taken
  sMessage = "Congratulations!!\n"                              'Build sMessage
  sMessage &= Str(siMoves) & " Moves\n"                         'Build sMessage
  sMessage &= "Time = " & Str(dTimerDiff)                       'Build sMessage
  Message(sMessage, "OK")                                       'Put up a congratulatory message
  Me.Close                                                      'Close the form
Endif

End

Public Sub RebuildForm()                                        'To clear the Form and rebuild with the Tiles in the new postion
Dim hButton As Button                                           'We need Buttons
Dim byCount, byTemp As Byte                                     'Various variables
Dim siFontH As Short

Me.Children.clear                                               'Clear the Form of all Objects

For Each byTemp In byPos                                        'For each 'Position'
  If byTemp = 99 Then                                           'If the Position's value is 99 then it's the space
    AddPanel                                                    'Go to the AddPanel routine
  Else                                                          'If the Position's value is NOT 99 then
    hButton = New Button(Me) As "AllButtons"                    'Create a new Button
  With hButton                                                  'With the following properties
    .Text = Str(byPos[byCount])                                 'Text as stored in byPos
    .Tag = Str(byPos[byCount])                                  'Tag as stored in byPos
    .Height = (Me.Height - 10) / 4                              'Set the Button height
    .Width = (Me.Width - 10) / 4                                'Set the Button width
    .Font.Bold = True                                           'Set the Font to Bold
      End With
    If Me.Width > Me.Height Then                                'If Form Width is greater than Form Width then..
      siFontH = Me.Height                                       'siFontH = Form Height
    Else                                                        'Else..
      siFontH = Me.Width                                        'siFontH = Form Width
    End If
  hButton.Font.size = siFontH / 16                              'Set Font height
  Endif

  Inc byCount                                                   'Increase counter
Next

End

Public Sub Form_Resize()                                        'If the form is resized

RebuildForm                                                     'Rebuild the Form

End

Public Sub IsItSolvable() As Boolean                            'To check if the puzzle is solvable
Dim bSolvable, bBlankOnEven As Boolean                          'Triggers
Dim siCount0, siCount1, siInversion As Short                    'Counters

For siCount0 = 0 To byPos.Max                                   'Loop through the positions
  If byPos[siCount0] = 99 Then                                  'The blank
    If InStr("0,1,2,3,8,9,10,11,", Str(siCount0 & ",")) Then    'Is the blank on an even row (counting from the bottom) if so..
      bBlankOnEven = True                                       'bBlankOnEven = True
    End If
    Continue                                                    'Go to the end of the loop
  End If
  For siCount1 = siCount0 + 1 To byPos.Max                      'Loop through the positions
    If byPos[siCount0] > byPos[siCount1] Then Inc siInversion   'Counts the inversions
  Next                                                          'See https://www.cs.bham.ac.uk/~mdr/teaching/modules04/java2/TilesSolvability.html
Next

If bBlankOnEven And Odd(siInversion) Then bSolvable = True      'Blank is on an even row (counting from the bottom) then the number of inversions in a solvable situation is odd
If Not bBlankOnEven And Even(siInversion) Then bSolvable = True 'Blank is on an odd row (counting from the bottom) then the number of inversions in a solvable situation is even

Return bSolvable                                                'Return the value

End

Public Sub Form_Close()

Settings.Write(Me, "Window")                                    'Store the window position and size

End

[http://www.cogier.com/gambas/Copuzzle.png Click here for image of game in play]

Go

package main

import (
	"fmt"
	"math/rand"
	"strings"
	"time"
)

func main() {
	rand.Seed(time.Now().UnixNano())
	p := newPuzzle()
	p.play()
}

type board [16]cell
type cell uint8
type move uint8

const (
	up move = iota
	down
	right
	left
)

func randMove() move { return move(rand.Intn(4)) }

var solvedBoard = board{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 0}

func (b *board) String() string {
	var buf strings.Builder
	for i, c := range b {
		if c == 0 {
			buf.WriteString("  .")
		} else {
			_, _ = fmt.Fprintf(&buf, "%3d", c)
		}
		if i%4 == 3 {
			buf.WriteString("\n")
		}
	}
	return buf.String()
}

type puzzle struct {
	board board
	empty int // board[empty] == 0
	moves int
	quit  bool
}

func newPuzzle() *puzzle {
	p := &puzzle{
		board: solvedBoard,
		empty: 15,
	}
	// Could make this configurable, 10==easy, 50==normal, 100==hard
	p.shuffle(50)
	return p
}

func (p *puzzle) shuffle(moves int) {
	// As with other Rosetta solutions, we use some number
	// of random moves to "shuffle" the board.
	for i := 0; i < moves || p.board == solvedBoard; {
		if p.doMove(randMove()) {
			i++
		}
	}
}

func (p *puzzle) isValidMove(m move) (newIndex int, ok bool) {
	switch m {
	case up:
		return p.empty - 4, p.empty/4 > 0
	case down:
		return p.empty + 4, p.empty/4 < 3
	case right:
		return p.empty + 1, p.empty%4 < 3
	case left:
		return p.empty - 1, p.empty%4 > 0
	default:
		panic("not reached")
	}
}

func (p *puzzle) doMove(m move) bool {
	i := p.empty
	j, ok := p.isValidMove(m)
	if ok {
		p.board[i], p.board[j] = p.board[j], p.board[i]
		p.empty = j
		p.moves++
	}
	return ok
}

func (p *puzzle) play() {
	fmt.Printf("Starting board:")
	for p.board != solvedBoard && !p.quit {
		fmt.Printf("\n%v\n", &p.board)
		p.playOneMove()
	}
	if p.board == solvedBoard {
		fmt.Printf("You solved the puzzle in %d moves.\n", p.moves)
	}
}

func (p *puzzle) playOneMove() {
	for {
		fmt.Printf("Enter move #%d (U, D, L, R, or Q): ", p.moves+1)
		var s string
		if n, err := fmt.Scanln(&s); err != nil || n != 1 {
			continue
		}

		s = strings.TrimSpace(s)
		if s == "" {
			continue
		}

		var m move
		switch s[0] {
		case 'U', 'u':
			m = up
		case 'D', 'd':
			m = down
		case 'L', 'l':
			m = left
		case 'R', 'r':
			m = right
		case 'Q', 'q':
			fmt.Printf("Quiting after %d moves.\n", p.moves)
			p.quit = true
			return
		default:
			fmt.Println(`
Please enter "U", "D", "L", or "R" to move the empty cell
up, down, left, or right. You can also enter "Q" to quit.
Upper or lowercase is accepted and only the first non-blank
character is important (i.e. you may enter "up" if you like).
`)
			continue
		}

		if !p.doMove(m) {
			fmt.Println("That is not a valid move at the moment.")
			continue
		}

		return
	}
}

Haskell

import Data.Array
import System.Random

type Puzzle = Array (Int, Int) Int

main :: IO ()
main = do
    putStrLn "Please enter the difficulty level: 0, 1 or 2"
    userInput <- getLine
    let diffLevel = read userInput
    if userInput == "" || any (\c -> c < '0' || c > '9') userInput || diffLevel > 2 || diffLevel < 0
        then putStrLn "That is not a valid difficulty level." >> main
        else shufflePuzzle ([10, 50, 100] !! diffLevel) solvedPuzzle >>= gameLoop

gameLoop :: Puzzle -> IO ()
gameLoop puzzle
    | puzzle == solvedPuzzle = putStrLn "You solved the puzzle!" >> printPuzzle puzzle
    | otherwise = do
    printPuzzle puzzle
    putStrLn "Please enter number to move"
    userInput <- getLine
    if any (\c -> c < '0' || c > '9') userInput
        then putStrLn "That is not a valid number." >> gameLoop puzzle
        else let move = read userInput in
            if move `notElem` validMoves puzzle
                then putStrLn "This move is not available." >> gameLoop puzzle
                else gameLoop (applyMove move puzzle)

validMoves :: Puzzle -> [Int]
validMoves puzzle = [puzzle ! (row', column') |
                     row' <- [rowEmpty-1..rowEmpty+1], column' <- [columnEmpty-1..columnEmpty+1],
                     row' < 4, row' >= 0, column' < 4, column' >= 0,
                     (row' == rowEmpty) /= (column' == columnEmpty)]
    where (rowEmpty, columnEmpty) = findIndexOfNumber 16 puzzle

applyMove :: Int -> Puzzle -> Puzzle
applyMove numberToMove puzzle = puzzle // [(indexToMove, 16), (emptyIndex, numberToMove)]
    where indexToMove = findIndexOfNumber numberToMove puzzle
          emptyIndex = findIndexOfNumber 16 puzzle

findIndexOfNumber :: Int -> Puzzle -> (Int, Int)
findIndexOfNumber number puzzle = case filter (\idx -> number == puzzle ! idx)
                                              (indices puzzle) of
                                      [idx] -> idx
                                      _ -> error "BUG: number not in puzzle"

printPuzzle :: Puzzle -> IO ()
printPuzzle puzzle = do
    putStrLn "+--+--+--+--+"
    putStrLn $ "|" ++ formatCell (0, 0) ++ "|" ++ formatCell (0, 1) ++ "|" ++ formatCell (0, 2) ++ "|" ++ formatCell (0, 3) ++ "|"
    putStrLn "+--+--+--+--+"
    putStrLn $ "|" ++ formatCell (1, 0) ++ "|" ++ formatCell (1, 1) ++ "|" ++ formatCell (1, 2) ++ "|" ++ formatCell (1, 3) ++ "|"
    putStrLn "+--+--+--+--+"
    putStrLn $ "|" ++ formatCell (2, 0) ++ "|" ++ formatCell (2, 1) ++ "|" ++ formatCell (2, 2) ++ "|" ++ formatCell (2, 3) ++ "|"
    putStrLn "+--+--+--+--+"
    putStrLn $ "|" ++ formatCell (3, 0) ++ "|" ++ formatCell (3, 1) ++ "|" ++ formatCell (3, 2) ++ "|" ++ formatCell (3, 3) ++ "|"
    putStrLn "+--+--+--+--+"
    where formatCell idx
              | i == 16 = "  "
              | i > 9 = show i
              | otherwise = " " ++ show i
              where i = puzzle ! idx

solvedPuzzle :: Puzzle
solvedPuzzle = listArray ((0, 0), (3, 3)) [1..16]

shufflePuzzle :: Int -> Puzzle -> IO Puzzle
shufflePuzzle 0 puzzle = return puzzle
shufflePuzzle numOfShuffels puzzle = do
    let moves = validMoves puzzle
    randomIndex <- randomRIO (0, length moves - 1)
    let move = moves !! randomIndex
    shufflePuzzle (numOfShuffels - 1) (applyMove move puzzle)

Output:

Please enter the difficulty level: 0, 1 or 2
0
+--+--+--+--+
| 1| 6| 2| 4|
+--+--+--+--+
| 5|10| 3| 8|
+--+--+--+--+
| 9|14| 7|11|
+--+--+--+--+
|13|  |15|12|
+--+--+--+--+
Please enter number to move
14
+--+--+--+--+
| 1| 6| 2| 4|
+--+--+--+--+
| 5|10| 3| 8|
+--+--+--+--+
| 9|  | 7|11|
+--+--+--+--+
|13|14|15|12|
+--+--+--+--+
Please enter number to move

Harbour



#include "inkey.ch"
#include "Box.ch"


procedure Main()
    // console init
    SET SCOREBOARD OFF
    SetMode(30,80)
    ret := 0

    // main loop
    yn := .F.
    DO WHILE yn == .F.
        // draw console
        cls
        @ 0, 0 TO MaxRow(), MaxCol() DOUBLE
        SetColor("BG+/B,W/N")
        @ 0, 4 SAY "  Slidng puzzle game  "
        SetColor()

        // input size of grid
        tam := 0
        @ MaxRow() - 2, 4 SAY "Size of grid: " GET tam PICTURE "9"
        READ

        // Initialize numbers
        lista := ARRAY (tam * tam)
        FOR z := 1 TO tam * tam
            lista[z] := z
        NEXT
        lista1 := lista
        grid := ARRAY (tam,tam)

        // populate grid with numbers
        FOR i := 1 TO tam
            FOR j := 1 TO tam
                grid[i,j] := lista1[ (i-1) * tam + j]
            NEXT
        NEXT
        Mostra(@grid)
        InKey(0)

        // initialize the game
        n := 0
        t := 0
        lista := lista1     // lista for scrambling, lista1 preserve numbers in order
        DO WHILE .T.
            // scrambling numbers
            FOR i := 1 TO tam*tam
                n := Int ( ft_Rand1(tam * tam - 1) + 1 )
                t := lista[n]
                lista[n] := lista[i]
                lista[i] := t
            NEXT
            // have solution?
            possp := 0
            invct := 0  // change counter
            FOR i := 1 TO tam * tam -1
                IF lista[i] != tam*tam
                    FOR j := i + 1 TO tam * tam
                        IF lista[j] != tam*tam
                            IF lista[i] > lista[j]
                                invct++
                            ENDIF
                        ENDIF
                    NEXT
                ELSE
                    possp := i
                ENDIF
            NEXT
            linv := If( ( (invct % 2) == 0 ), .T., .F.)
            lkin := If( ( (tam - Int( (possp -1) / tam )) % 2) == 0, .T., .F. )

            IF ( (tam % 2) != 0)    // if grid size is odd
                IF linv                 // if number of positions changes is even, solvable
                    EXIT
                ELSE
                    LOOP                // if is odd, not solvable, scramble more
                ENDIF               // if grid size is even
            ELSE
                                        // If changes is even and space position is in odd line
                                        // or changes is odd and space position is in even line
                                        // (XOR condition) is solvable
                IF (linv .AND. !lkin) .OR. (!linv .AND. lkin) // XOR !!!
                    EXIT
                ElSE                    // else scramble more
                    LOOP
                ENDIF
            ENDIF

        ENDDO

        // populate the grid with scrambled numbers
        FOR i := 1 TO tam
            FOR j := 1 TO tam
                grid[i,j] := lista[ (i-1) * tam + j]
            NEXT
        NEXT
        ret := Mostra(@grid)

    // play
        key := 0
        DO WHILE LastKey() != K_ESC
            key := 0
            // find the space coords
            xe := 0
            ye := 0
            lv := tam*tam
            FOR i := 1 TO tam
                FOR j := 1 TO tam
                    IF grid[i,j] == lv
                        xe :=i
                        ye :=j
                    ENDIF
                NEXT
            NEXT
            // the direction keys
            key := inkey(0)
            DO CASE
                CASE key == K_UP
                    IF xe > 1
                        grid[xe,ye] := grid[xe-1,ye]
                        grid[xe-1,ye] := lv
                    ENDIF
                    ret := Mostra(@grid)
                CASE key == K_DOWN
                    IF xe < tam
                        grid[xe,ye] := grid[xe+1,ye]
                        grid[xe+1,ye] := lv
                    ENDIF
                    ret := Mostra(@grid)
                CASE key == K_LEFT
                    IF ye > 1
                        grid[xe,ye] := grid[xe,ye-1]
                        grid[xe,ye-1] := lv
                    ENDIF
                    ret := Mostra(@grid)
                CASE key == K_RIGHT
                    IF ye < tam
                        grid[xe,ye] := grid[xe,ye+1]
                        grid[xe,ye+1] := lv
                    ENDIF
                    ret := Mostra(@grid)
            ENDCASE
            IF ret == tam*tam-1                             // ret is qtty numbers in position
                @ MaxRow() - 3, 4 SAY "Fim de jogo!"        // if ret == (size*size) -1
                key := K_ESC                                // all numbers in position
                EXIT                                        // game solved
            ENDIF
        ENDDO
        @ MaxRow() - 2, 4 SAY "Deseja sair? (yn): " GET yn PICTURE "Y"
        READ
        @ MaxRow() - 3, 4 SAY "              "
    ENDDO
return NIL

FUNCTION Mostra(grid)
    // Show the gris
    fim := 0                                                    // how many numbers in position?
    SetColor("BG+/B,W/N")
    @ 5,10 , 5 + tam * 2, 9 + tam * 4 BOX B_SINGLE + Space(1)
    i := 0
    FOR y := 1 TO tam
        FOR x := 1 TO tam
            IF grid[x,y] == tam * tam                           // show space
                SetColor(" B/GR+, W/N")
                @ x*2 + 4, i + 11 SAY "  "
                SetColor("BG+/B,W/N")
            ELSE
                IF ( (x-1) * tam + y ) == grid[x,y]             // show number in position
                    SetColor("W/G,W/N")
                    @ x*2 + 4, i + 11 SAY grid[x,y] PICTURE "99"
                    fim++
                ELSE                                            // show number out position
                    SetColor("BG+/B,W/N")
                    @ x*2 + 4, i + 11 SAY grid[x,y] PICTURE "99"
                ENDIF
            ENDIF
        NEXT
        i = i + 4
    NEXT
    SetColor(" W/N, BG+/B")
RETURN fim

J

Implementation:

require'general/misc/prompt'

genboard=:3 :0
  b=. ?~16
  if. 0<C.!.2 b do.
    b=. (<0 _1)C. b
  end.
  a: (b i.0)} <"0 b
)

done=: (<"0]1+i.15),a:

shift=: |.!._"0 2
taxi=: |:,/"2(_1 1 shift i.4 4),_1 1 shift"0 1/ i.4 4

showboard=:3 :0
  echo 'current board:'
  echo 4 4$y
)

help=:0 :0

  Slide a number block into the empty space
  until you get:
┌──┬──┬──┬──┐
│1 │2 │3 │4 │
├──┼──┼──┼──┤
│5 │6 │7 │8 │
├──┼──┼──┼──┤
│9 │10│11│12│
├──┼──┼──┼──┤
│13│14│15│  │
└──┴──┴──┴──┘
  Or type 'q' to quit.
)

getmove=:3 :0
  showboard y
  blank=. y i. a:
  options=. /:~ ;y {~ _ -.~ blank { taxi
  whilst. -. n e. options do.
    echo 'Valid moves: ',":options
    t=. prompt 'move which number? '
    if. 'q' e. t do.
      echo 'giving up'
      throw.
    elseif. 'h' e. t do.
      echo help
      showboard y
    end.
    n=. {._".t
  end.
  (<blank,y i.<n) C. y
)

game=: 3 :0
  echo '15 puzzle'
  echo 'h for help, q to quit'
  board=. genboard''
  whilst. -. done-:board do.
    board=. getmove board
  end.
  showboard board
  echo 'You win.'
)

Most of this is user interface code. We initially shuffle the numbers randomly, then check their parity and swap the first and last squares if needed. Then, for each move, we allow the user to pick one of the taxicab neighbors of the empty square.

A full game would be too big to be worth showing here, so for the purpose of giving a glimpse of what this looks like in action we replace the random number generator with a constant:

   game''
15 puzzle
h for help, q to quit
current board:
┌──┬──┬──┬──┐
│1 │2 │3 │4 │
├──┼──┼──┼──┤
│5 │6 │7 │8 │
├──┼──┼──┼──┤
│9 │10│  │11│
├──┼──┼──┼──┤
│13│14│15│12│
└──┴──┴──┴──┘
Valid moves: 7 10 11 15
move which number? 11
current board:
┌──┬──┬──┬──┐
│1 │2 │3 │4 │
├──┼──┼──┼──┤
│5 │6 │7 │8 │
├──┼──┼──┼──┤
│9 │10│11│  │
├──┼──┼──┼──┤
│13│14│15│12│
└──┴──┴──┴──┘
Valid moves: 8 11 12
move which number? 12
current board:
┌──┬──┬──┬──┐
│1 │2 │3 │4 │
├──┼──┼──┼──┤
│5 │6 │7 │8 │
├──┼──┼──┼──┤
│9 │10│11│12│
├──┼──┼──┼──┤
│13│14│15│  │
└──┴──┴──┴──┘
You win.

== {{header|Java}}== {{works with|Java|8}}

package fifteenpuzzle;

import java.awt.*;
import java.awt.event.*;
import java.util.Random;
import javax.swing.*;

class FifteenPuzzle extends JPanel {

    private final int side = 4;
    private final int numTiles = side * side - 1;

    private final Random rand = new Random();
    private final int[] tiles = new int[numTiles + 1];
    private final int tileSize;
    private int blankPos;
    private final int margin;
    private final int gridSize;
    private boolean gameOver;

    private FifteenPuzzle() {
        final int dim = 640;

        margin = 80;
        tileSize = (dim - 2 * margin) / side;
        gridSize = tileSize * side;

        setPreferredSize(new Dimension(dim, dim + margin));
        setBackground(Color.WHITE);
        setForeground(new Color(0x6495ED)); // cornflowerblue
        setFont(new Font("SansSerif", Font.BOLD, 60));

        gameOver = true;

        addMouseListener(new MouseAdapter() {
            @Override
            public void mousePressed(MouseEvent e) {
                if (gameOver) {
                    newGame();

                } else {

                    int ex = e.getX() - margin;
                    int ey = e.getY() - margin;

                    if (ex < 0 || ex > gridSize || ey < 0 || ey > gridSize) {
                        return;
                    }

                    int c1 = ex / tileSize;
                    int r1 = ey / tileSize;
                    int c2 = blankPos % side;
                    int r2 = blankPos / side;

                    int clickPos = r1 * side + c1;

                    int dir = 0;
                    if (c1 == c2 && Math.abs(r1 - r2) > 0) {
                        dir = (r1 - r2) > 0 ? 4 : -4;

                    } else if (r1 == r2 && Math.abs(c1 - c2) > 0) {
                        dir = (c1 - c2) > 0 ? 1 : -1;
                    }

                    if (dir != 0) {
                        do {
                            int newBlankPos = blankPos + dir;
                            tiles[blankPos] = tiles[newBlankPos];
                            blankPos = newBlankPos;
                        } while (blankPos != clickPos);
                        tiles[blankPos] = 0;
                    }

                    gameOver = isSolved();
                }
                repaint();
            }
        });

        newGame();
    }

    private void newGame() {
        do {
            reset();
            shuffle();
        } while (!isSolvable());
        gameOver = false;
    }

    private void reset() {
        for (int i = 0; i < tiles.length; i++) {
            tiles[i] = (i + 1) % tiles.length;
        }
        blankPos = tiles.length - 1;
    }

    private void shuffle() {
        // don't include the blank space in the shuffle, leave it
        // in the home position
        int n = numTiles;
        while (n > 1) {
            int r = rand.nextInt(n--);
            int tmp = tiles[r];
            tiles[r] = tiles[n];
            tiles[n] = tmp;
        }
    }

    /*  Only half the permutations of the puzzle are solvable.

        Whenever a tile is preceded by a tile with higher value it counts
        as an inversion. In our case, with the blank space in the home
        position, the number of inversions must be even for the puzzle
        to be solvable.

        See also:
        www.cs.bham.ac.uk/~mdr/teaching/modules04/java2/TilesSolvability.html
     */
    private boolean isSolvable() {
        int countInversions = 0;
        for (int i = 0; i < numTiles; i++) {
            for (int j = 0; j < i; j++) {
                if (tiles[j] > tiles[i]) {
                    countInversions++;
                }
            }
        }
        return countInversions % 2 == 0;
    }

    private boolean isSolved() {
        if (tiles[tiles.length - 1] != 0) {
            return false;
        }
        for (int i = numTiles - 1; i >= 0; i--) {
            if (tiles[i] != i + 1) {
                return false;
            }
        }
        return true;
    }

    private void drawGrid(Graphics2D g) {
        for (int i = 0; i < tiles.length; i++) {
            int r = i / side;
            int c = i % side;
            int x = margin + c * tileSize;
            int y = margin + r * tileSize;

            if (tiles[i] == 0) {
                if (gameOver) {
                    g.setColor(Color.GREEN);
                    drawCenteredString(g, "\u2713", x, y);
                }
                continue;
            }

            g.setColor(getForeground());
            g.fillRoundRect(x, y, tileSize, tileSize, 25, 25);
            g.setColor(Color.blue.darker());
            g.drawRoundRect(x, y, tileSize, tileSize, 25, 25);
            g.setColor(Color.WHITE);

            drawCenteredString(g, String.valueOf(tiles[i]), x, y);
        }
    }

    private void drawStartMessage(Graphics2D g) {
        if (gameOver) {
            g.setFont(getFont().deriveFont(Font.BOLD, 18));
            g.setColor(getForeground());
            String s = "click to start a new game";
            int x = (getWidth() - g.getFontMetrics().stringWidth(s)) / 2;
            int y = getHeight() - margin;
            g.drawString(s, x, y);
        }
    }

    private void drawCenteredString(Graphics2D g, String s, int x, int y) {
        FontMetrics fm = g.getFontMetrics();
        int asc = fm.getAscent();
        int des = fm.getDescent();

        x = x + (tileSize - fm.stringWidth(s)) / 2;
        y = y + (asc + (tileSize - (asc + des)) / 2);

        g.drawString(s, x, y);
    }

    @Override
    public void paintComponent(Graphics gg) {
        super.paintComponent(gg);
        Graphics2D g = (Graphics2D) gg;
        g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                RenderingHints.VALUE_ANTIALIAS_ON);

        drawGrid(g);
        drawStartMessage(g);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            JFrame f = new JFrame();
            f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            f.setTitle("Fifteen Puzzle");
            f.setResizable(false);
            f.add(new FifteenPuzzle(), BorderLayout.CENTER);
            f.pack();
            f.setLocationRelativeTo(null);
            f.setVisible(true);
        });
    }
}

Javascript

Play it [http://paulo-jorente.de/webgames/15p/ here]


var board, zx, zy, clicks, possibles, clickCounter, oldzx = -1, oldzy = -1;
function getPossibles() {
    var ii, jj, cx = [-1, 0, 1, 0], cy = [0, -1, 0, 1];
    possibles = [];
    for( var i = 0; i < 4; i++ ) {
        ii = zx + cx[i]; jj = zy + cy[i];
        if( ii < 0 || ii > 3 || jj < 0 || jj > 3 ) continue;
        possibles.push( { x: ii, y: jj } );
    }
}
function updateBtns() {
    var b, v, id;
    for( var j = 0; j < 4; j++ ) {
        for( var i = 0; i < 4; i++ ) {
            id = "btn" + ( i + j * 4 );
            b = document.getElementById( id );
            v = board[i][j];
            if( v < 16 ) {
                b.innerHTML = ( "" + v );
                b.className = "button"
            }
            else {
                b.innerHTML = ( "" );
                b.className = "empty";
            }
        }
    }
    clickCounter.innerHTML = "Clicks: " + clicks;
}
function shuffle() {
    var v = 0, t;
    do {
        getPossibles();
        while( true ) {
            t = possibles[Math.floor( Math.random() * possibles.length )];
            console.log( t.x, oldzx, t.y, oldzy )
            if( t.x != oldzx || t.y != oldzy ) break;
        }
        oldzx = zx; oldzy = zy;
        board[zx][zy] = board[t.x][t.y];
        zx = t.x; zy = t.y;
        board[zx][zy] = 16;
    } while( ++v < 200 );
}
function restart() {
    shuffle();
    clicks = 0;
    updateBtns();
}
function checkFinished() {
    var a = 0;
    for( var j = 0; j < 4; j++ ) {
        for( var i = 0; i < 4; i++ ) {
            if( board[i][j] < a ) return false;
            a = board[i][j];
        }
    }
    return true;
}
function btnHandle( e ) {
    getPossibles();
    var c = e.target.i, r = e.target.j, p = -1;
    for( var i = 0; i < possibles.length; i++ ) {
        if( possibles[i].x == c && possibles[i].y == r ) {
            p = i;
            break;
        }
    }
    if( p > -1 ) {
        clicks++;
        var t = possibles[p];
        board[zx][zy] = board[t.x][t.y];
        zx = t.x; zy = t.y;
        board[zx][zy] = 16;
        updateBtns();
        if( checkFinished() ) {
            setTimeout(function(){
                alert( "WELL DONE!" );
                restart();
            }, 1);
        }
    }
}
function createBoard() {
    board = new Array( 4 );
    for( var i = 0; i < 4; i++ ) {
        board[i] = new Array( 4 );
    }
    for( var j = 0; j < 4; j++ ) {
        for( var i = 0; i < 4; i++ ) {
            board[i][j] = ( i + j * 4 ) + 1;
        }
    }
    zx = zy = 3; board[zx][zy] = 16;
}
function createBtns() {
    var b, d = document.createElement( "div" );
    d.className += "board";
    document.body.appendChild( d );
    for( var j = 0; j < 4; j++ ) {
        for( var i = 0; i < 4; i++ ) {
            b = document.createElement( "button" );
            b.id = "btn" + ( i + j * 4 );
            b.i = i; b.j = j;
            b.addEventListener( "click", btnHandle, false );
            b.appendChild( document.createTextNode( "" ) );
            d.appendChild( b );
        }
    }
    clickCounter = document.createElement( "p" );
    clickCounter.className += "txt";
    document.body.appendChild( clickCounter );
}
function start() {
    createBtns();
    createBoard();
    restart();
}

Html to test


<!DOCTYPE html>
<html><head><meta charset="UTF-8">
<title>15 Puzzle</title>
<script src="p15.js"></script>
<style>
    html,body{padding:0; margin:0;padding-top:8vh;background:#222;color:#111}
    .txt{color:#fff;text-align:center;font-size:5vh}
    .board{padding:0;margin:auto;width:33vh;height:33vh}
    .button, .empty{border:0;font-size:3.5vh;margin:0.5vh;padding:0;height:6vh;width:7.25vh;line-height:5vh;
    vertical-align:middle;background:#fff;text-align:center;border-radius:3px;cursor:pointer;float:left}
    .empty{background:#333;border:1px solid #111}
</style>
</head><body onload="start()"></body></html>

Julia


using Random

const size = 4
const puzzle = string.(reshape(1:16, size, size))
puzzle[16] = " "
rng = MersenneTwister(Int64(round(time())))
shufflepuzzle() = (puzzle .= shuffle(rng, puzzle))
findtile(t) = findfirst(x->x == t, puzzle)
findhole() = findtile(" ")

function issolvable()
    inversioncount = 1
    asint(x) = (puzzle[x] == " ") ? 0 : parse(Int64, puzzle[x])
    for i in 1:size^2-1, j in i:size^2
        if puzzle[i] == " " || puzzle[j] == " "
            continue
        end
        if parse(Int, puzzle[i]) < parse(Int, puzzle[j])
            inversioncount += 1
        end
    end
    if size % 2 == 1
        return inversioncount % 2 == 0
    end
    pos = findhole()
    inversioncount += pos[2]
    return inversioncount & 1 == 0
end

function nexttohole()
    holepos = findhole()
    row = holepos[1]
    col = holepos[2]
    if row == 1
        if col == 1
            return [[row, col + 1], [row + 1, col]]
        elseif col == size
            return [[row, col - 1], [row + 1, col]]
        else
            return [[row, col - 1], [row, col + 1], [row + 1, col]]
        end
    elseif row == size
        if col == 1
            return [[row - 1, col], [row, col + 1]]
        elseif col == size
            return [[row - 1, col], [row, col - 1]]
        else
            return [[row - 1, col], [row, col - 1], [row, col + 1]]
        end
    else
        if col == 1
            return [[row - 1, col], [row, col + 1], [row + 1, col]]
        elseif col == size
            return [[row - 1, col], [row, col - 1], [row + 1, col]]
        else
            return [[row - 1, col], [row, col - 1], [row, col + 1], [row + 1, col]]
        end
    end
end

possiblemoves() = map(pos->puzzle[pos[1], pos[2]], nexttohole())

function movehole(tiletofill)
    if tiletofill in possiblemoves()
        curpos = findtile(tiletofill)
        holepos = findhole()
        puzzle[holepos] = tiletofill
        puzzle[curpos] = " "
    else
        println("Bad tile move $tiletofill.\nPossible moves are $(possiblemoves()).")
    end
end

function printboard()
    ppuz(x,y) = print(lpad(rpad(puzzle[x,y], 3), 4), "|")
    print("+----+----+----+----+\n|")
    for j in 1:size, i in 1:size
        ppuz(i,j)
        if i == size
            print("\n")
            if j < size
                 print("|")
            end
        end
    end
    println("+----+----+----+----+")

end

function puzzle15play()
    solved() = (puzzle[1:15] == string.(1:15))
    shufflepuzzle()
    println("This puzzle is", issolvable() ? " " : " not ", "solvable.")
    while !solved()
        printboard()
        print("Possible moves are: $(possiblemoves()), 0 to exit. Your move? =>  ")
        s = readline()
        if s == "0"
            exit(0)
        end
        movehole(s)
    end
    printboard()
    println("Puzzle solved.")
end

puzzle15play()

{{output}}


This puzzle is solvable.
+----+----+----+----+
| 5  | 7  | 14 |    |
| 4  | 3  | 13 | 12 |
| 10 | 1  | 6  | 9  |
| 8  | 15 | 11 | 2  |
+----+----+----+----+
Possible moves are: ["14", "12"], 0 to exit. Your move? =>  12
+----+----+----+----+
| 5  | 7  | 14 | 12 |
| 4  | 3  | 13 |    |
| 10 | 1  | 6  | 9  |
| 8  | 15 | 11 | 2  |
+----+----+----+----+
Possible moves are: ["13", "12", "9"], 0 to exit. Your move? =>

Kotlin

{{trans|Java}}

// version 1.1.3

import java.awt.BorderLayout
import java.awt.Color
import java.awt.Dimension
import java.awt.Font
import java.awt.Graphics
import java.awt.Graphics2D
import java.awt.RenderingHints
import java.awt.event.MouseAdapter
import java.awt.event.MouseEvent
import java.util.Random
import javax.swing.JFrame
import javax.swing.JPanel
import javax.swing.SwingUtilities

class FifteenPuzzle(dim: Int, val margin: Int) : JPanel() {

    private val rand = Random()
    private val tiles = IntArray(16)
    private val tileSize = (dim - 2 * margin) / 4
    private val gridSize = tileSize * 4
    private var blankPos = 0

    init {
        preferredSize = Dimension(dim, dim)
        background = Color.white
        val cornflowerBlue = 0x6495ED
        foreground = Color(cornflowerBlue)
        font = Font("SansSerif", Font.BOLD, 60)

        addMouseListener(object : MouseAdapter() {
            override fun mousePressed(e: MouseEvent) {
                val ex = e.x - margin
                val ey = e.y - margin
                if (ex !in 0..gridSize || ey !in 0..gridSize) return

                val c1 = ex / tileSize
                val r1 = ey / tileSize
                val c2 = blankPos % 4
                val r2 = blankPos / 4
                if ((c1 == c2 && Math.abs(r1 - r2) == 1) ||
                    (r1 == r2 && Math.abs(c1 - c2) == 1)) {
                    val clickPos = r1 * 4 + c1
                    tiles[blankPos] = tiles[clickPos]
                    tiles[clickPos] = 0
                    blankPos = clickPos
                }
                repaint()
            }
        })

        shuffle()
    }

    private fun shuffle() {
        do {
            reset()
            // don't include the blank space in the shuffle,
            // leave it in the home position
            var n = 15
            while (n > 1) {
                val r = rand.nextInt(n--)
                val tmp = tiles[r]
                tiles[r] = tiles[n]
                tiles[n] = tmp
            }
        } while (!isSolvable())
    }

    private fun reset() {
        for (i in 0 until tiles.size) {
            tiles[i] = (i + 1) % tiles.size
        }
        blankPos = 15
    }

    /*  Only half the permutations of the puzzle are solvable.

        Whenever a tile is preceded by a tile with higher value it counts
        as an inversion. In our case, with the blank space in the home
        position, the number of inversions must be even for the puzzle
        to be solvable.
    */

    private fun isSolvable(): Boolean {
        var countInversions = 0
        for (i in 0 until 15) {
            (0 until i)
                .filter { tiles[it] > tiles[i] }
                .forEach { countInversions++ }
        }
        return countInversions % 2 == 0
    }

    private fun drawGrid(g: Graphics2D) {
        for (i in 0 until tiles.size) {
            if (tiles[i] == 0) continue

            val r = i / 4
            val c = i % 4
            val x = margin + c * tileSize
            val y = margin + r * tileSize

            with(g) {
                color = foreground
                fillRoundRect(x, y, tileSize, tileSize, 25, 25)
                color = Color.black
                drawRoundRect(x, y, tileSize, tileSize, 25, 25)
                color = Color.white
            }
            drawCenteredString(g, tiles[i].toString(), x, y)
        }
    }

    private fun drawCenteredString(g: Graphics2D, s: String, x: Int, y: Int) {
        val fm = g.fontMetrics
        val asc = fm.ascent
        val des = fm.descent

        val xx = x + (tileSize - fm.stringWidth(s)) / 2
        val yy = y + (asc + (tileSize - (asc + des)) / 2)

        g.drawString(s, xx, yy)
    }

    override fun paintComponent(gg: Graphics) {
        super.paintComponent(gg)
        val g = gg as Graphics2D
        g.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
            RenderingHints.VALUE_ANTIALIAS_ON)
        drawGrid(g)
    }
}

fun main(args: Array<String>) {
    SwingUtilities.invokeLater {
        val f = JFrame()
        with(f) {
            defaultCloseOperation = JFrame.EXIT_ON_CLOSE
            title = "Fifteen Puzzle"
            isResizable = false
            add(FifteenPuzzle(640, 80), BorderLayout.CENTER)
            pack()
            setLocationRelativeTo(null)
            isVisible = true
        }
    }
}

Liberty BASIC

{{trans|Commodore BASIC}} {{works with|Just BASIC}}


' 15-PUZZLE GAME
' ********************************
dim d(16)
dim ds$(16) ' Board pieces
dim sh(3)
call introAndLevel v
call buildBoard v
call printPuzzle
do
  print "To move a piece, enter its number: "
  input x
  while isMoveValid(x, y, z) = 0
    print "Wrong move."
    call printPuzzle
    print "To move a piece, enter its number: "
    input x
  wend
  d(z) = x
  d(y) = 0
  call printPuzzle
loop until isPuzzleComplete()
print "YOU WON!"
end

sub printPuzzle
  for p = 1 to 16
    if d(p) = 0 then
      ds$(p) = "     "
    else
      s$ = str$(d(p))
      ds$(p) = left$("   ", 3 - len(s$)) + s$ + "  "
    end if
  next p
  print "+-----+-----+-----+-----+"
  print "|"; ds$(1); "|"; ds$(2); "|"; ds$(3); "|"; ds$(4); "|"
  print "+-----+-----+-----+-----+"
  print "|"; ds$(5); "|"; ds$(6); "|"; ds$(7); "|"; ds$(8); "|"
  print "+-----+-----+-----+-----+"
  print "|"; ds$(9); "|"; ds$(10); "|";ds$(11); "|"; ds$(12); "|"
  print "+-----+-----+-----+-----+"
  print "|"; ds$(13); "|"; ds$(14); "|"; ds$(15); "|"; ds$(16); "|"
  print "+-----+-----+-----+-----+"
end sub

sub introAndLevel byref level
  cls
  sh(1) = 10
  sh(2) = 50
  sh(3) = 100
  print "15 PUZZLE GAME"
  print
  print
  print "Please enter level of difficulty,"
  do
    print "1 (easy), 2 (medium) or 3 (hard): ";
    input level
  loop while (level < 1) or (level > 3)
end sub

sub buildBoard level
  ' Set pieces in correct order first
  for p = 1 to 15
    d(p) = p
  next p
  d(16) = 0 ' 0 = empty piece/slot
  z = 16 ' z = empty position
  print
  print "Shuffling pieces";
  for n = 1 to sh(level)
    print ".";
    do
      x = int(rnd(0) * 4) + 1
      select case x
        case 1
          r = z - 4
        case 2
          r = z + 4
        case 3
          if (z - 1) mod 4 <> 0 then
            r = z - 1
          end if
        case 4
          if z mod 4 <> 0 then
            r = z + 1
          end if
      end select
    loop while (r < 1) or (r > 16)
    d(z) = d(r)
    z = r
    d(z) = 0
  next n
  cls
end sub

function isMoveValid(ax, byref ay, byref az)
  mv = 0
  if (ax >= 1) or (ax <= 15) then
    ' Find position of piece ax
    p = 1
    while d(p) <> ax
      p = p + 1
      if p > 16 then
        print "UH OH!"
        stop
      end if
    wend
    ay = p
    ' Find position of empty piece
    p = 1
    while d(p) <> 0
      p = p + 1
      if p > 16 then
        print "UH OH!"
        stop
      end if
    wend
    az = p
    ' Check if empty piece is above, below, left or right to piece x
    if (ay - 4 = az) or _
      (ay + 4 = az) or _
      ((ay - 1 = az) and (az mod 4 <> 0)) or _
      ((ay + 1 = az) and (ay mod 4 <> 0)) then
      mv = 1
    end if
  end if
  isMoveValid = mv
end function

function isPuzzleComplete()
  pc = 0
  p = 1
  while (p < 16) and (d(p) = p)
    p = p + 1
  wend
  if p = 16 then
    pc = 1
  end if
  isPuzzleComplete = pc
end function

LiveCode


#Please note that all this code can be performed in livecode with just few mouse clicks
#This is just a pure script exampe
on OpenStack
   show me  #Usually not necessary
   #tile creation
   set the width of the templateButton to 50
   set the height of the templateButton to 50
   repeat with i=1 to 16
      create button
      set the label of  button i to i
      if i =1 then
         set the top of button 1 to 0
         set the left of button 1 to 0
      end if
      if i > 1 and 1 <=4  then
         set the left of button i to the right of button (i-1)
         set the top of button i to the top of button 1
      end if
      if i >= 5 and i <= 8 then
         set the top of button i to the bottom of button 1
         if i = 5 then
            set the left of button i to the left of button 1
         else
            set the left of button i to the right of button (i - 1)
         end if
      end if
      if i >= 9 and i <= 12 then
         set the top of button i to the bottom of button 5
         if i = 9 then
            set the left of button i to the left of button 1
         else
            set the left of button i to the right of button (i - 1)
         end if
      end if
      if i >= 13 and i <= 16 then
         set the top of button i to the bottom of button 9
         if i = 13 then
            set the left of button i to the left of button 1
         else
            set the left of button i to the right of button (i - 1)
         end if
      end if
      #this is usally the script directly wirtten in the objects, it's really weird this way
      put "on MouseUp" &CR& "if checkDistance(the label of me) then" & CR &"put the loc of me into temp" into ts
      put CR& "set the loc of me to the loc of button 16" after ts
      put CR& "set the loc of button 16 to temp" & Cr & "end if " &CR &"End MouseUp" after ts
      set the script of button i to ts
   end repeat
   #graphic adjustements
   set the visible of button 16 to false
   set the width of this stack to the right of button 16
   set the height of this stack to the bottom of button 16
end openStack

function checkDistance i
   if (((the top of button i - the bottom of button 16) = 0 OR (the top of button 16 - the bottom of button i) = 0) AND the left of button i = the left of button 16) OR (((the left of button i - the right of button 16) = 0 OR (the right of button i - the left of button 16) = 0) AND the top of button i = the top of button 16) then
      return true
   else
      return false
   end if
end checkDistance

Screenshot: [https://s24.postimg.org/uc6fx7kph/Livecode15_Puzzle_Game.png]

Lua


math.randomseed( os.time() )
local puz = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 0 }
local dir = { { 1, 0 }, { -1, 0 }, { 0, 1 }, { 0, -1 } }
local sx, sy = 4, 4

function isValid( tx, ty )
    return tx > 0 and tx < 5 and ty > 0 and ty < 5
end
function display()
    io.write( "\n\n" )
    for j = 1, 4 do
        io.write( "+----+----+----+----+\n" )
        for i = 1, 4 do
            local d = puz[i + j * 4 - 4]
            io.write( ": " )
            if d < 10 then io.write( " " ) end
            if d < 1  then
                io.write( "  " )
            else
                io.write( string.format( "%d ", d ) )
            end
        end
        io.write( ":\n" )
    end
    io.write( "+----+----+----+----+\n\n" )
end
function getUserNove()
    local moves, r, tx, ty = {}
    for d = 1, 4 do
        tx = sx; ty = sy
        tx = tx + dir[d][1]; ty = ty + dir[d][2]

        if isValid( tx, ty ) then
            table.insert( moves, puz[tx + ty * 4 - 4] )
        end
    end

    io.write( "Your possible moves are: " )
    for i = 1, #moves do
        io.write( string.format( "%d ", moves[i] ) )
    end

    io.write ( "\nYour move: " ); r = tonumber( io.read() )
    if r ~= nil then
        for i = 1, #moves do
            if moves[i] == r then return r end
        end
    end
    print( "Invalid move!" )
    return -1
end
function checked( r )
    for i = 1, #puz do
        if puz[i] == r then
            puz[i] = 0
            sx = 1 + ( i - 1 ) % 4; sy = math.floor( ( i + 3 ) / 4 )
        elseif puz[i] == 0 then
            puz[i] = r
        end
    end
    for i = 2, #puz - 1 do
        if puz[i - 1] + 1 ~= puz[i] then return false end
    end
    return true
end
function beginGame()
    local r, d, tx, ty
    while( true ) do
        for i = 1, 100 do
            while( true ) do
                tx = sx; ty = sy; d = math.random( 4 )
                tx = tx + dir[d][1]; ty = ty + dir[d][2]
                if isValid( tx, ty ) then break end
            end
            puz[sx + sy * 4 - 4] = puz[tx + ty * 4 - 4]
            puz[tx + ty * 4 - 4] = 0; sx = tx; sy = ty
        end
        while( true ) do
            display(); r = getUserNove()
            if r > 0 then
                if checked( r ) then
                    display()
                    io.write( "\nDone!\n\nPlay again (Y/N)?" )
                    r = io.read()
                    if r ~= "Y" and r ~= "y" then
                        return
                    else
                        break
                    end
                end
            end
        end
    end
end
-- [ entry point ] --
beginGame()

{{out}}


+----+----+----+----+
:  1 : 15 :  7 :  3 :
+----+----+----+----+
: 14 :  9 :  2 :  4 :
+----+----+----+----+
:  5 : 13 :    : 10 :
+----+----+----+----+
:  6 : 12 :  8 : 11 :
+----+----+----+----+

Your possible moves are: 10 13 8 2
Your move:

{{trans|COMMODORE BASIC}}

M2000 Interpreter

{{trans|COMMODORE BASIC}} I make a function RND() and I set Base for arrays to 1 Also I put some semi colons to Print statement Also I have to put variables after NEXT statements To be actual BASIC compatible we have to set FOR NEXT like BASIC, because for M2000 the direction defined by the starting-ending values, so always we get at least one time the block between FOR NEXT. So we can use:

SET SWITCHES "+FOR"

But here we don't have to skip FOR NEXT and no STEP clause used.

Also the code is not the best, because we can move from 4 position to 5 (we can't do that with real puzzle)


Module Puzzle15 {

      00 BASE 1 : DEF RND(X)=RND
      10 REM 15-PUZZLE GAME
      20 REM COMMODORE BASIC 2.0
      30 REM ********************************
      40 GOSUB 400 : REM INTRO AND LEVEL
      50 GOSUB 510 : REM SETUP BOARD
      60 GOSUB 210 : REM PRINT PUZZLE
      70 PRINT "TO MOVE A PIECE, ENTER ITS NUMBER:"
      80 INPUT X
      90 GOSUB 730 : REM CHECK IF MOVE IS VALID
      100 IF MV=0 THEN PRINT "WRONG MOVE" : GOSUB 1050 : GOTO 60
      110 D(Z)=X : D(Y)=0
      120 GOSUB 210 : REM PRINT PUZZLE
      130 GOSUB 950 : REM CHECK IF PUZZLE COMPLETE
      140 IF PC THEN 160
      150 GOTO 70
      160 PRINT"YOU WON!"
      170 END
      180 REM
      190 REM *******************************
      200 REM PRINT/DRAW THE PUZZLE
      210 FOR P=1 TO 16
      220   IF D(P)=0 THEN D$(P)="     " : GOTO 260
      230   S$=STR$(D(P))
      240   N=LEN(S$)
      250   D$(P) = LEFT$("   ",3-N)+S$+"  "
      260 NEXT P
      270 PRINT "+-----+-----+-----+-----+"
      280 PRINT "!";D$(1);"!";D$(2);"!";D$(3);"!";D$(4);"!"
      290 PRINT "+-----+-----+-----+-----+"
      300 PRINT "!";D$(5);"!";D$(6);"!";D$(7);"!";D$(8);"!"
      310 PRINT "+-----+-----+-----+-----+"
      320 PRINT "!";D$(9);"!";D$(10);"!";D$(11);"!";D$(12);"!"
      330 PRINT "+-----+-----+-----+-----+"
      340 PRINT "!";D$(13);"!";D$(14);"!";D$(15);"!";D$(16);"!"
      350 PRINT "+-----+-----+-----+-----+"
      360 RETURN
      370 REM
      380 REM *******************************
      390 REM INTRO AND LEVEL OF DIFFICULTY
      400 PRINT CHR$(147)
      410 DIM SH(3) : SH(1)=10 : SH(2)=50 : SH(3)=100
      420 PRINT "15 PUZZLE GAME FOR COMMODORE BASIC 2.0" : PRINT : PRINT
      430 PRINT "PLEASE ENTER LEVEL OF DIFFICULTY,"
      440 PRINT "1(EASY), 2(MEDIUM) OR 3(HARD):";
      450 INPUT V
      460 IF V<1 OR V>3 THEN 440
      470 RETURN
      480 REM
      490 REM *******************************
      500 REM BUILD THE BOARD
      510 DIM D(16) : DIM D$(16) : REM BOARD PIECES
      520 REM SET PIECES IN CORRECT ORDER FIRST
      530 FOR P=1 TO 15
      540   D(P) = P
      550 NEXT P
      560 D(16) = 0 : REM 0 = EMPTY PIECE/SLOT
      570 Z=16      : REM Z = EMPTY POSITION
      580 PRINT: PRINT "SHUFFLING PIECES";
      590 FOR N=1 TO SH(V)
      600   PRINT".";
      610   X = INT(RND(0)*4)+1
      620   R = Z+(X=1)*4-(X=2)*4+(X=3)-(X=4)
      630   IF R<1 OR R>16 THEN 610
      640   D(Z)=D(R)
      650   Z=R
      660   D(Z)=0
      670 NEXT N
      680 PRINT CHR$(147)
      690 RETURN
      700 REM
      710 REM *******************************
      720 REM CHECK IF MOVE IS VALID
      730 MV = 0
      740 IF X<1 OR X>15 THEN RETURN
      750 REM FIND POSITION OF PIECE X
      760 P=1
      770 IF D(P)=X THEN Y=P : GOTO 810
      780 P=P+1 : IF P>16 THEN PRINT "UH OH!" : STOP
      790 GOTO 770
      800 REM FIND POSITION OF EMPTY PIECE
      810 P=1
      820 IF D(P)=0 THEN Z=P : GOTO 860
      830 P=P+1 : IF P>16 THEN PRINT "UH OH!" : STOP
      840 GOTO 820
      850 PRINT Y;Z
      860 REM CHECK IF EMPTY PIECE IS ABOVE, BELOW, LEFT OR RIGHT TO PIECE X
      870 IF Y-4=Z THEN MV=1 : RETURN
      880 IF Y+4=Z THEN MV=1 : RETURN
      890 IF Y-1=Z THEN MV=1 : RETURN
      900 IF Y+1=Z THEN MV=1 : RETURN
      910 RETURN
      920 REM
      930 REM *******************************
      940 REM CHECK IF PUZZLE IS COMPLETE / GAME OVER
      950 PC = 0
      960 P=1
      970 IF D(P)<>P THEN RETURN
      980 P=P+1
      990 IF P<16 THEN 970
      1000 PC = 1
      1010 RETURN
      1020 REM
      1030 REM ******************************
      1040 REM A SMALL DELAY
      1050 FOR T=0 TO 400
      1060 NEXT T
      1070 RETURN
}
Puzzle15

Mercury

The ideal in Mercury is to have a declarative module that encodes the game logic, and then separate modules to implement a human player with text commands (here), or keyed commands, or some kind of AI player, and so on. fifteen.print/3 is a arguably a smudge on fifteen's interface:

:- module fifteen.
:- interface.
:- use_module random, io.

:- type board.
:- type invalid_board
    --->    invalid_board(board).
:- type move
    --->    up
    ;       down
    ;       left
    ;       right.

    % init(Board):
    % Board is fifteen game in its initial state
    %
:- pred init(board::out) is det.

    % print(Board, !IO)
:- pred print(board::in, io.io::di, io.io::uo) is det.

    % Shuffled(Board, !RS):
    % Board is a fifteen game in a random (but valid) state.
    %
:- pred shuffled(board::out, random.supply::mdi, random.supply::muo) is det.

    % space(Board) = I:
    % I is the index of the blank space in the board.
    % Throws invalid_board iff there is no blank.
    %
:- func space(board) = int.

    % move(Move, !Board):
    % Move the blank space in a board in the given direction.
    % Fails if this is an invalid move to make.
    %
:- pred move(move::in, board::in, board::out) is semidet.

:- implementation.
:- import_module bt_array, int, list, string.
:- use_module array, exception.

:- type board == bt_array(int).

init(B) :- from_list(0, (1 .. 15) ++ [0], B).

print(B, !IO) :-
    Tile = (func(N) = ( if N = 0 then s("  ") else s(string.format("%2d", [i(N)])) )),
    io.format("\
|----+----+----+----|
| %s | %s | %s | %s |
| %s | %s | %s | %s |
| %s | %s | %s | %s |
| %s | %s | %s | %s |
|----+----+----+----|
",
        map(Tile, to_list(B)), !IO).

shuffled(!:B, !RS) :-
    init(!:B),
    some [!A] (
        array.from_list(to_list(!.B), !:A),
        array.random_permutation(!A, !RS),
        from_list(0, array.to_list(!.A), !:B)
    ).

space(Board) = I :- space(0, Board, I).

:- pred space(int::in, board::in, int::out) is det.
space(N, Board, I) :-
    ( if semidet_lookup(Board, N, X) then
        ( if X = 0 then
            N = I
        else
            space(N + 1, Board, I)
        )
    else
        exception.throw(invalid_board(Board))
    ).

:- pred swap(int::in, int::in, board::in, board::out) is det.
swap(I, J, !B) :-
    X = !.B ^ elem(I),
    Y = !.B ^ elem(J),
    !B ^ elem(I) := Y,
    !B ^ elem(J) := X.

move(M, !B) :- move(space(!.B), M, !B).

:- pred move(int::in, move::in, board::in, board::out) is semidet.
move(I, up, !B) :-
    I >= 4,
    swap(I, I - 4, !B).
move(I, down, !B) :-
    I < 12,
    swap(I, I + 4, !B).
move(I, left, !B) :-
    not (I = 0 ; I = 4 ; I = 8 ; I = 12),
    swap(I, I - 1, !B).
move(I, right, !B) :-
    not (I = 3 ; I = 7 ; I = 11 ; I = 15),
    swap(I, I + 1, !B).

As used:

:- module play_fifteen.
:- interface.
:- import_module io.
:- pred main(io::di, io::uo) is det.
:- implementation.
:- import_module string.
:- use_module random, fifteen, exception.

main(!IO) :-
    seed(Seed, !IO),
    random.init(Seed, RS),
    fifteen.shuffled(Board, RS, _),
    fifteen.print(Board, !IO),
    play(Board, !IO).

:- type input_command
    --->    up ; down ; left ; right
    ;       quit.

:- type command
    --->    move(fifteen.move)
    ;       quit.

:- pred input(input_command::in, command::out) is det.
input(up, move(fifteen.up)).
input(down, move(fifteen.down)).
input(left, move(fifteen.left)).
input(right, move(fifteen.right)).
input(quit, quit).

:- pred command(string::in, command::out) is semidet.
command(String, C) :-
    Term = chomp(String) ++ ".",
    io.read_from_string("play_fifteen", Term, length(Term),
        ok(I), io.posn(0, 0, 0), _),
    input(I, C).

:- pred play(fifteen.board::in, io::di, io::uo) is det.
play(!.B, !IO) :-
    io.write_string("Move? ", !IO),
    io.read_line_as_string(Res, !IO),
    (
        Res = eof
    ;
        Res = error(_),
        exception.throw(Res)
    ;
        Res = ok(String),
        ( if command(String, Command) then
            (
                Command = quit,
                io.write_string("Bye :(\n", !IO)
            ;
                Command = move(Move),
                ( if fifteen.move(Move, !B) then
                    ( if fifteen.init(!.B) then
                        fifteen.print(!.B, !IO),
                        io.write_string("You win!\n", !IO)
                    else
                        fifteen.print(!.B, !IO),
                        play(!.B, !IO)
                    )
                else
                    io.write_string("Invalid move.\n", !IO),
                    play(!.B, !IO)
                )
            )
        else
            io.write_string("I didn't understand that.\n", !IO),
            play(!.B, !IO)
        )
    ).

:- pragma foreign_decl("C", "#include <time.h>").
:- pred seed(int::out, io::di, io::uo) is det.
:- pragma foreign_proc("C",
    seed(Seed::out, _IO0::di, _IO::uo),
    [promise_pure, will_not_call_mercury],
"
    Seed = time(NULL);
").

MUMPS


15Game ;
	; setting the layout
	f i=1:1:15 s box(i)=16-i
	; no number for box 16
	s box(16)=""
	f  {
	; initialise i for incrementation
		s i=0
	; write out the 4-by-4 box
		f row=1:1:4 {
			w !?20
			f column=1:1:4 {
				s i=$i(i)
				w $j(box(i),2)," "
			}
		}
		r !!,"Enter number to move (q to quit): ",number
		q:number="q"
		f i=1:1:16 q:box(i)=""
		if box(i)="" {
			if i>4,number=box(i-4) {
				s box(i)=number,box(i-4)=""
				w !!
			}
			elseif i>1,i'=5,i'=9,i'=13,number=box(i-1) {
				s box(i)=number,box(i-1)=""
				w !!
			}
			elseif i<16,i'=4,i'=8,i'=12,number=box(i+1) {
				s box(i)=number,box(i+1)=""
				w !!
			}
			elseif i<13,number=box(i+4) {
				s box(i)=number,box(i+4)=""
				w !!
			}
			else {
				w !,"You have to enter a number either above, below, left or right of the empty space."
			}
		}
	}
	q

Nim

import random, strutils

type
  Tile = uint8
  Board = array[16, Tile]

proc generateBoard: Board =
  for i in 1..15:
    while true:
      let pos = rand 15
      if result[pos] == 0:
        result[pos] = i.Tile
        break

func isSolved(board: Board): bool =
  for i in 0..<board.high:
    if i != board[i].int - 1:
      return false
  true

func findTile(b: Board, n: Tile): int =
  for i in 0..b.high:
    if b[i] == n:
      return i

func canSwap(a, b: int): bool =
  let dist = a - b
  dist == 4 or dist == -4 or
    (dist == 1 and a mod 4 != 0) or
    (dist == -1 and b mod 4 != 0)

func pad(i: Tile): string =
  if i == 0:
    "|  "
  elif i < 10:
    "| " & $i
  else:
    "|" & $i

proc draw(b: Board) =
  echo "+--+--+--+--+\n",
     b[0].pad, b[1].pad, b[2].pad, b[3].pad,
     "|\n+--+--+--+--+\n",
     b[4].pad, b[5].pad, b[6].pad, b[7].pad,
     "|\n+--+--+--+--+\n",
     b[8].pad, b[9].pad, b[10].pad, b[11].pad,
     "|\n+--+--+--+--+\n",
     b[12].pad, b[13].pad, b[14].pad, b[15].pad,
     "|\n+--+--+--+--+"

when isMainModule:
  randomize()
  var
    board = generateBoard()
    empty = board.findTile 0
  while not isSolved board:
    draw board
    stdout.write "Choose tile to move: "
    let
      num = stdin.readLine.parseInt.Tile
      pos = board.findTile num
    if num < 16'u8 and num > 0'u8 and canSwap(empty, pos):
      swap board[empty], board[pos]
      empty = pos
    else: echo "Incorrect tile"
  draw board
  echo "Puzzle solved"

{{out}}

+--+--+--+--+
| 3| 7|10| 4|
+--+--+--+--+
| 5|  | 6|11|
+--+--+--+--+
|12| 8|15| 1|
+--+--+--+--+
| 9|14|13| 2|
+--+--+--+--+
Choose tile to move: 6
+--+--+--+--+
| 3| 7|10| 4|
+--+--+--+--+
| 5| 6|  |11|
+--+--+--+--+
|12| 8|15| 1|
+--+--+--+--+
| 9|14|13| 2|
+--+--+--+--+

OCaml

module Puzzle =
struct
  type t = int array
  let make () =
    [| 15; (* 0: the empty space *)
        0;  1;  2;  3;
        4;  5;  6;  7;
        8;  9; 10; 11;
       12; 13; 14;  |]

  let move p n =
    let hole, i = p.(0), p.(n) in
    p.(0) <- i;
    p.(n) <- hole

  let print p =
    let out = Array.make 16 "   " in
    for i = 1 to 15 do
      out.(p.(i)) <- Printf.sprintf " %2d" i
    done;
    for i = 0 to 15 do
      if (i mod 4) = 0 then print_newline ();
      print_string out.(i);
    done

  let shuffle p n =
    for i = 1 to n do
      move p (1 + Random.int 15)
    done
end

let play () =
  let p = Puzzle.make () in
  Puzzle.shuffle p 20;
  while true do
    Puzzle.print p;
    print_string " > ";
    Puzzle.move p (read_line () |> int_of_string)
  done

To move, input the number to slide into the blank. If you accidentally make an impossible move you can undo it by repeating the last input. A nice self-checked puzzle, the same as if you were physically moving the pieces around.

{{out}}

# play ();;

  8 11  7 13
  3  6    15
  9 10 12  4
  1  5 14  2 > 6

  8 11  7 13
  3     6 15
  9 10 12  4
  1  5 14  2 > 11

  8     7 13
  3 11  6 15
  9 10 12  4
  1  5 14  2 > 8

     8  7 13
  3 11  6 15
  9 10 12  4
  1  5 14  2 > 3

  3  8  7 13
    11  6 15
  9 10 12  4
  1  5 14  2 > 11

  3  8  7 13
 11     6 15
  9 10 12  4
  1  5 14  2 > 8

  3     7 13
 11  8  6 15
  9 10 12  4
  1  5 14  2 > 3

     3  7 13
 11  8  6 15
  9 10 12  4
  1  5 14  2 >

Pascal

This is Free Pascal(version >= 3.0.4) text mode implementation. To make a move, the user needs to enter the number of the selected tile.


program fifteen;
{$mode objfpc}
{$modeswitch advancedrecords}
{$coperators on}
uses
  SysUtils, crt;
type
  TPuzzle = record
  private
  const
    ROW_COUNT  = 4;
    COL_COUNT  = 4;
    CELL_COUNT = ROW_COUNT * COL_COUNT;
    RAND_RANGE = 101;
  type
    TTile          = 0..Pred(CELL_COUNT);
    TAdjacentCell  = (acLeft, acTop, acRight, acBottom);
    TPossibleMoves = set of TTile;
    TCellAdjacency = set of TAdjacentCell;
    TBoard         = array[0..Pred(CELL_COUNT)] of TTile;
  class var
    HBar: string;
  var
    FBoard: TBoard;
    FZeroPos,
    FMoveCount: Integer;
    FZeroAdjacency: TCellAdjacency;
    FPossibleMoves: TPossibleMoves;
    FSolved: Boolean;
    procedure DoMove(aTile: TTile);
    procedure CheckPossibleMoves;
    procedure PrintBoard;
    procedure PrintPossibleMoves;
    procedure TestSolved;
    procedure GenerateBoard;
    class constructor Init;
  public
    procedure New;
    function  UserMoved: Boolean;
    property  MoveCount: Integer read FMoveCount;
    property  Solved: Boolean read FSolved;
  end;

procedure TPuzzle.DoMove(aTile: TTile);
var
  Pos: Integer = -1;
  Adj: TAdjacentCell;
begin
  for Adj in FZeroAdjacency do
    begin
      case Adj of
        acLeft:   Pos := Pred(FZeroPos);
        acTop:    Pos := FZeroPos - COL_COUNT;
        acRight:  Pos := Succ(FZeroPos);
        acBottom: Pos := FZeroPos + COL_COUNT;
      end;
      if FBoard[Pos] = aTile then
        break;
    end;
  FBoard[FZeroPos] := aTile;
  FZeroPos := Pos;
  FBoard[Pos] := 0;
end;

procedure TPuzzle.CheckPossibleMoves;
var
  Row, Col: Integer;
begin
  Row := FZeroPos div COL_COUNT;
  Col := FZeroPos mod COL_COUNT;
  FPossibleMoves := [];
  FZeroAdjacency := [];
  if Row > 0 then
    begin
      FPossibleMoves += [FBoard[FZeroPos - COL_COUNT]];
      FZeroAdjacency += [acTop];
    end;
  if Row < Pred(ROW_COUNT) then
    begin
      FPossibleMoves += [FBoard[FZeroPos + COL_COUNT]];
      FZeroAdjacency += [acBottom];
    end;
  if Col > 0 then
    begin
      FPossibleMoves += [FBoard[Pred(FZeroPos)]];
      FZeroAdjacency += [acLeft];
    end;
  if Col < Pred(COL_COUNT) then
    begin
      FPossibleMoves += [FBoard[Succ(FZeroPos)]];
      FZeroAdjacency += [acRight];
    end;
end;

procedure TPuzzle.PrintBoard;
const
  Space = ' ';
  VBar  = '|';
  VBar1 = '| ';
  VBar2 = '|  ';
  VBar3 = '|    ';
var
  I, J, Pos, Tile: Integer;
  Row: string;
begin
  ClrScr;
  Pos := 0;
  WriteLn(HBar);
  for I := 1 to ROW_COUNT do
    begin
      Row := '';
      for J := 1 to COL_COUNT do
        begin
          Tile := Integer(FBoard[Pos]);
          case Tile of
            0:    Row += VBar3;
            1..9: Row += VBar2 + Tile.ToString + Space;
          else
            Row += VBar1 + Tile.ToString + Space;
          end;
          Inc(Pos);
        end;
      WriteLn(Row + VBar);
      WriteLn(HBar);
    end;
  if not Solved then
    PrintPossibleMoves;
end;

procedure TPuzzle.PrintPossibleMoves;
var
  pm: TTile;
  spm: string = '';
begin
  for pm in FPossibleMoves do
    spm += Integer(pm).ToString + ' ';
  WriteLn('possible moves: ', spm);
end;

procedure TPuzzle.TestSolved;
  function IsSolved: Boolean;
  var
    I: Integer;
  begin
    for I := 0 to CELL_COUNT - 3 do
      if FBoard[I] <> Pred(FBoard[Succ(I)]) then
        exit(False);
    Result := True;
  end;
begin
  FSolved := IsSolved;
  if not Solved then
    CheckPossibleMoves;
end;

procedure TPuzzle.GenerateBoard;
var
  I, CurrMove, SelMove: Integer;
  Tile: TTile;
begin
  FZeroPos := Pred(CELL_COUNT);
  FBoard[FZeroPos] := 0;
  for I := 0 to CELL_COUNT - 2 do
    FBoard[I] := Succ(I);
  for I := 1 to Random(RAND_RANGE) do
    begin
      CheckPossibleMoves;
      SelMove := 0;
      for Tile in FPossibleMoves do
        Inc(SelMove);
      SelMove := Random(SelMove);
      CurrMove := 0;
      for Tile in FPossibleMoves do
        begin
          if CurrMove = SelMove then
            begin
              DoMove(Tile);
              break;
            end;
          Inc(CurrMove);
        end;
    end;
end;

class constructor TPuzzle.Init;
var
  I: Integer;
begin
  HBar := '';
  for I := 1 to COL_COUNT do
    HBar += '+----';
  HBar += '+';
end;

procedure TPuzzle.New;
begin
  FSolved := False;
  FMoveCount := 0;
  GenerateBoard;
  CheckPossibleMoves;
  PrintBoard;
end;

function TPuzzle.UserMoved: Boolean;
const
  Sorry          = 'sorry, ';
  InvalidInput   = ' is invalid input';
  ImpossibleMove = ' is impossible move';
var
  UserInput: string;
  Tile: Integer = 0;
begin
  ReadLn(UserInput);
  case LowerCase(UserInput) of
    'c', 'cancel': exit(False);
  end;
  Result := True;
  if not Tile.TryParse(UserInput, Tile) then
    begin
      WriteLn(Sorry, UserInput, InvalidInput);
      exit;
    end;
  if not (Tile in [1..Pred(CELL_COUNT)]) then
    begin
      WriteLn(Sorry, Tile, InvalidInput);
      exit;
    end;
  if not (Tile in FPossibleMoves) then
    begin
      WriteLn(Sorry, Tile, ImpossibleMove);
      PrintPossibleMoves;
      exit;
    end;
  DoMove(Tile);
  Inc(FMoveCount);
  TestSolved;
  PrintBoard;
end;

procedure PrintStart;
begin
  ClrScr;
  WriteLn('Fifteen puzzle start:');
  WriteLn('  enter a tile number and press <enter> to move' );
  WriteLn('  enter Cancel(C) and press <enter> to exit' );
  Window(10, 4, 58, 21);
end;

procedure Terminate;
begin
  ClrScr;
  Window(1, 1, 80, 25);
  ClrScr;
  WriteLn('Fifteen puzzle exit.');
  Halt;
end;

function UserWantContinue(aMoveCount: Integer): Boolean;
var
  UserInput: string;
begin
  WriteLn('Congratulations! Puzzle solved in ', aMoveCount, ' moves.');
  WriteLn('Play again(Yes(Y)/<any button>)?');
  ReadLn(UserInput);
  case LowerCase(UserInput) of
    'y', 'yes': exit(True);
  end;
  Result := False;
end;

procedure Run;
var
  Puzzle: TPuzzle;
begin
  Randomize;
  PrintStart;
  repeat
    Puzzle.New;
    while not Puzzle.Solved do
      if not Puzzle.UserMoved then
        Terminate;
    if not UserWantContinue(Puzzle.MoveCount) then
      Terminate;
  until False;
end;

begin
  Run;
end.

Perl

Tk version

{{libheader|Tk}} {{libheader|Perl/Tk}} This Tk 15 puzzle implementation also shows the solvability of the current puzzle and the relative difficulty of it. On verbosity shows how the solvability is calculated. The program has some extra feature like font size and color scheme but also the possibility to set the intial board disposition. This program was originally posted by me at [http://www.perlmonks.org/?node_id=1192660 perlmonks]



use strict;
use warnings;

use Getopt::Long;
use List::Util 1.29 qw(shuffle pairmap first all);
use Tk;
    # 5 options                                 1 label text
my ($verbose,@fixed,$nocolor,$charsize,$extreme,$solvability);

unless (GetOptions (
                     'verbose!' => \$verbose,
                     'tiles|positions=i{16}' => \@fixed,
                     'nocolor' => \$nocolor,
                     'charsize|size|c|s=i' => \$charsize,
                     'extreme|x|perl' => \$extreme,
                    )
        ) { die "invalid arguments!";}

@fixed = &check_req_pos(@fixed) if @fixed;

my $mw = Tk::MainWindow->new(-bg=>'black',-title=>'Giuoco del 15');

if ($nocolor){ $mw->optionAdd( '*Button.background',   'ivory' );}

$mw->optionAdd('*Button.font', 'Courier '.($charsize or 16).' bold' );
$mw->bind('<Control-s>', sub{#&init_board;
                             &shuffle_board});

my $top_frame = $mw->Frame( -borderwidth => 2, -relief => 'groove',
                           )->pack(-expand => 1, -fill => 'both');

$top_frame->Label( -textvariable=>\$solvability,
                  )->pack(-expand => 1, -fill => 'both');

my $game_frame = $mw->Frame(  -background=>'saddlebrown',
                              -borderwidth => 10, -relief => 'groove',
                            )->pack(-expand => 1, -fill => 'both');

# set victory conditions in pairs of coordinates
my @vic_cond =  pairmap {
       [$a,$b]
    } qw(0 0 0 1 0 2 0 3
         1 0 1 1 1 2 1 3
         2 0 2 1 2 2 2 3
         3 0 3 1 3 2 3 3);

my $board = [];

my $victorious = 0;

&init_board;

if ( $extreme ){ &extreme_perl}

&shuffle_board;

MainLoop;

################################################################################
sub init_board{
  # tiles from 1 to 15
  for (0..14){
     $$board[$_]={
          btn=>$game_frame->Button(
                            -text => $_+1,
                            -relief => 'raised',
                            -borderwidth => 3,
                            -height => 2,
                            -width =>  4,
                                  -background=>$nocolor?'ivory':'gold1',
                                  -activebackground => $nocolor?'ivory':'gold1',
                                  -foreground=> $nocolor?'black':'DarkRed',
                                  -activeforeground=>$nocolor?'black':'DarkRed'
          ),
          name => $_+1,     # x and y set by shuffle_board
     };
     if (($_+1) =~ /^(2|4|5|7|10|12|13|15)$/ and !$nocolor){
         $$board[$_]{btn}->configure(
                                  -background=>'DarkRed',
                                  -activebackground => 'DarkRed',
                                  -foreground=> 'gold1',
                                  -activeforeground=>'gold1'
         );
     }
   }
   # empty tile
   $$board[15]={
          btn=>$game_frame->Button(
                            -relief => 'sunken',
                            -borderwidth => 3,
                            -background => 'lavender',
                            -height => 2,
                            -width =>  4,
          ),
          name => 16,      # x and y set by shuffle_board
     };
}
################################################################################
sub shuffle_board{
    if ($victorious){
        $victorious=0;
        &init_board;
    }
    if (@fixed){
          my $index = 0;

          foreach my $tile(@$board[@fixed]){
                  my $xy = $vic_cond[$index];
                  ($$tile{x},$$tile{y}) = @$xy;
                  $$tile{btn}->grid(-row=>$$xy[0], -column=> $$xy[1]);
                  $$tile{btn}->configure(-command =>[\&move,$$xy[0],$$xy[1]]);
                  $index++;
          }
          undef @fixed;
    }
    else{
        my @valid = shuffle (0..15);
        foreach my $tile ( @$board ){
            my $xy = $vic_cond[shift @valid];
            ($$tile{x},$$tile{y}) = @$xy;
            $$tile{btn}->grid(-row=>$$xy[0], -column=> $$xy[1]);
            $$tile{btn}->configure(-command => [ \&move, $$xy[0], $$xy[1] ]);
        }
    }
    my @appear =  map {$_->{name}==16?'X':$_->{name}}
                  sort{$$a{x}<=>$$b{x}||$$a{y}<=>$$b{y}}@$board;
    print "\n".('-' x 57)."\n".
          "Appearence of the board:\n[@appear]\n".
          ('-' x 57)."\n".
          "current\tfollowers\t               less than current\n".
          ('-' x 57)."\n" if $verbose;
    # remove the, from now on inutile, 'X' for the empty space
    @appear = grep{$_ ne 'X'} @appear;
    my $permutation;
    foreach my $num (0..$#appear){
        last if $num == $#appear;
         my $perm;
          $perm += grep {$_ < $appear[$num]} @appear[$num+1..$#appear];
          if ($verbose){
            print "[$appear[$num]]\t@appear[$num+1..$#appear]".
            (" " x (37 - length "@appear[$num+1..$#appear]")).
            "\t   $perm ".($num == $#appear  - 1 ? '=' : '+')."\n";
          }
          $permutation+=$perm;
    }
    print +(' ' x 50)."----\n" if $verbose;
    if ($permutation % 2){
        print "Impossible game with odd permutations!".(' ' x 13).
              "$permutation\n"if $verbose;
        $solvability = "Impossible game with odd permutations [$permutation]\n".
                        "(ctrl-s to shuffle)".
                        (($verbose or $extreme) ? '' :
                           " run with --verbose to see more info");
        return;
    }
    # 105 is the max permutation
    my $diff =  $permutation == 0 ? 'SOLVED' :
                $permutation < 35 ? 'EASY  ' :
                $permutation < 70 ? 'MEDIUM' : 'HARD  ';
    print "$diff game with even permutations".(' ' x 17).
          "$permutation\n" if $verbose;
    $solvability = "$diff game with permutation parity of [$permutation]\n".
                    "(ctrl-s to shuffle)";
}
################################################################################
sub move{
    # original x and y
    my ($ox, $oy) = @_;
    my $self = first{$_->{x} == $ox and $_->{y} == $oy} @$board;
    return if $$self{name}==16;
    # check if one in n,s,e,o is the empty one
    my $empty = first {$_->{name} == 16 and
                          ( ($_->{x}==$ox-1 and $_->{y}==$oy) or
                            ($_->{x}==$ox+1 and $_->{y}==$oy) or
                            ($_->{x}==$ox and $_->{y}==$oy-1) or
                            ($_->{x}==$ox and $_->{y}==$oy+1)
                           )
                      } @$board;
    return unless $empty;
    # empty x and y
    my ($ex,$ey) = ($$empty{x},$$empty{y});
    # reconfigure emtpy tile
    $$empty{btn}->grid(-row => $ox, -column => $oy);
    $$empty{x}=$ox;    $$empty{y}=$oy;
    # reconfigure pressed tile
    $$self{btn}->grid(-row => $ex, -column => $ey);
    $$self{btn}->configure(-command => [ \&move, $ex, $ey ]);
    $$self{x}=$ex;    $$self{y}=$ey;
    # check for victory if the empty one is at the bottom rigth tile (3,3)
    &check_win if $$empty{x} == 3 and $$empty{y} == 3;
}
################################################################################
sub check_win{
     foreach my $pos (0..$#$board){
        return unless ( $$board[$pos]->{'x'} == $vic_cond[$pos]->[0] and
                        $$board[$pos]->{'y'} == $vic_cond[$pos]->[1]);
     }
     # victory!
     $victorious = 1;
     my @text =  ('Dis','ci','pu','lus','15th','','','at',
                  'P','e','r','l','M','o','n','ks*');
     foreach my $tile(@$board){
            $$tile{btn}->configure( -text=> shift @text,
                                    -command=>sub{return});
            $mw->update;
            sleep 1;
     }
}
################################################################################
sub check_req_pos{
    my @wanted = @_;
    # fix @wanted: seems GetOptions does not die if more elements are passed
    @wanted = @wanted[0..15];
    my @check = (1..16);
    unless ( all {$_ == shift @check} sort {$a<=>$b} @wanted ){
        die "tiles must be from 1 to 16 (empty tile)\nyou passed [@wanted]\n";
    }
    return map {$_-1} @wanted;
}
################################################################################
sub extreme_perl {
  $verbose = 0;
  $mw->optionAdd('*font', 'Courier 20 bold');
  my @extreme = (
    'if $0',                               #1
    "\$_=\n()=\n\"foo\"=~/o/g",            #2
    "use warnings;\n\$^W ?\nint((length\n'Discipulus')/3)\n:'15'",   #3
    "length \$1\nif \$^X=~\n\/(?:\\W)(\\w*)\n(?:\\.exe)\$\/", #4
    "use Config;\n\$Config{baserev}",                   #5.
    "(split '',\nvec('JAPH'\n,1,8))[0]",       #6
    "scalar map\n{ord(\$_)=~/1/g}\nqw(p e r l)", #7
    "\$_ = () =\n'J A P H'\n=~\/\\b\/g",   # 8
    "eval join '+',\nsplit '',\n(substr\n'12345',3,2)",  #9
    'printf \'%b\',2',                     #10
    "int(((1+sqrt(5))\n/ 2)** 7 /\nsqrt(5)+0.5)-2",    #11
    "split '',\nunpack('V',\n01234567))\n[6,4]",  # 12
    'J','A','P','H'                               # 13..16
  );
  foreach (0..15){
      $$board[$_]{btn}->configure(-text=> $extreme[$_],
                                 -height => 8,
                                  -width =>  16, ) if $extreme[$_];

  }
  @fixed = qw(0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15);
  $mw->after(5000,\&shuffle_board);#
}



console version

This short console program just poses solvable puzzles: it achieves this shuffling a solved board n times, where n defaults to 1000 but can be passed as first argument of the program in the command line. It was originally posted by me at [http://www.perlmonks.org/?node_id=1192865 perlmonks] but here a little modification was inserted to prevent wrong numbers to make the board messy.


use strict;
use warnings;

use List::Util qw(shuffle first);
my @tbl = ([1,2,3,4],[5,6,7,8],[9,10,11,12],[13,14,15,16]);
my $e = [3,3];
for (1..$ARGV[0]||1000) {
  my $new = (shuffle &ad($e))[0];
  $tbl[$e->[0]][$e->[1]] = $tbl[$new->[0]][$new->[1]];
  $tbl[$new->[0]]->[$new->[1]] = 16;
  $e = [$new->[0],$new->[1]];
}
while(1){
  print +(join ' ',map{$_==16?'  ':sprintf '%02s',$_}@{$tbl[$_]}),"\n" for 0..3;
  my $m = <STDIN>;
  chomp $m;
  die "Enter a number to move!" unless $m;
  if ($m > 15){
	warn "$m not in the board! Enter a tile from 1 to 15\n";
	next;
  }
  my $tile=first{$tbl[$$_[0]]->[$$_[1]]==$m}map{[$_,0],[$_,1],[$_,2],[$_,3]}0..3;
  my $new=first{$tbl[$$_[0]]->[$$_[1]]==16}&ad(grep{$tbl[$$_[0]]->[$$_[1]]==$m}
          map {[$_,0],[$_,1],[$_,2],[$_,3]}0..3);
  if ($new){$tbl[$$new[0]][$$new[1]]=$m;$tbl[$$tile[0]][$$tile[1]]=16;}
  system ($^O eq 'MSWin32' ? 'cls' : 'clear');
}
sub ad{
      my $e = shift; grep {$_->[0]<4 && $_->[1]<4 && $_->[0]>-1 && $_->[1]>-1}
      [$$e[0]-1,$$e[1]],[$$e[0]+1,$$e[1]],[$$e[0],$$e[1]-1],[$$e[0],$$e[1]+1]
}

Perl 6

{{works with|Rakudo|2018.06}} Most of this is interface code. Reused substantial portions from the [[2048#Perl_6|2048]] task. Use the arrow keys to slide tiles, press 'q' to quit or 'n' for a new puzzle. Requires a POSIX termios aware terminal. Ensures that the puzzle is solvable by shuffling the board with an even number of swaps, then checking for even taxicab parity for the empty space.

use Term::termios;

constant $saved   = Term::termios.new(fd => 1).getattr;
constant $termios = Term::termios.new(fd => 1).getattr;
# raw mode interferes with carriage returns, so
# set flags needed to emulate it manually
$termios.unset_iflags(<BRKINT ICRNL ISTRIP IXON>);
$termios.unset_lflags(< ECHO ICANON IEXTEN ISIG>);
$termios.setattr(:DRAIN);

# reset terminal to original setting on exit
END { $saved.setattr(:NOW) }

constant n    = 4; # board size
constant cell = 6; # cell width

constant $top = join '─' x cell, '┌', '┬' xx n-1, '┐';
constant $mid = join '─' x cell, '├', '┼' xx n-1, '┤';
constant $bot = join '─' x cell, '└', '┴' xx n-1, '┘';

my %dir = (
   "\e[A" => 'up',
   "\e[B" => 'down',
   "\e[C" => 'right',
   "\e[D" => 'left',
);

my @solved = [1,2,3,4],[5,6,7,8],[9,10,11,12],[13,14,15,' '];
my @board;
new();

sub new () {
    loop {
       @board = shuffle();
       last if parity-ok(@board);
   }
}

sub parity-ok (@b) {
    my $row = @b.first(/' '/,:k);
    my $col = @b[$row].first(/' '/,:k);
    so ([3,3] <<->> [$row,$col]).sum %% 2;
}

sub shuffle () {
    my @c = [1,2,3,4],[5,6,7,8],[9,10,11,12],[13,14,15,' '];
    for (^16).pick(*) -> $y, $x {
        my ($yd, $ym, $xd, $xm) = ($y div n, $y mod n, $x div n, $x mod n);
        my $temp    = @c[$ym;$yd];
        @c[$ym;$yd] = @c[$xm;$xd];
        @c[$xm;$xd] = $temp;
    }
    @c;
}

sub row (@row) { '│' ~ (join '│', @row».&center) ~ '│' }

sub center ($s){
    my $c   = cell - $s.chars;
    my $pad = ' ' x ceiling($c/2);
    sprintf "%{cell}s", "$s$pad";
}

sub draw-board {
    run('clear');
    print qq:to/END/;


	Press direction arrows to move.

	Press q to quit. Press n for a new puzzle.

	$top
	{ join "\n\t$mid\n\t", map { .&row }, @board }
	$bot

	{ (so @board ~~ @solved) ?? 'Solved!!' !! '' }
END
}

sub slide (@c is copy) {
    my $t = (grep { /' '/ }, :k, @c)[0];
    return @c unless $t and $t > 0;
    @c[$t,$t-1] = @c[$t-1,$t];
    @c;
}

proto sub move (|) {*};

multi move('up') {
    map { @board[*;$_] = reverse slide reverse @board[*;$_] }, ^n;
}

multi move('down') {
    map { @board[*;$_] = slide @board[*;$_] }, ^n;
}

multi move('left') {
    map { @board[$_] = reverse slide reverse @board[$_] }, ^n;
}

multi move('right') {
    map { @board[$_] = slide @board[$_] }, ^n;
}

loop {
    draw-board;

    # Read up to 4 bytes from keyboard buffer.
    # Page navigation keys are 3-4 bytes each.
    # Specifically, arrow keys are 3.
    my $key = $*IN.read(4).decode;

    move %dir{$key} if so %dir{$key};
    last if $key eq 'q'; # (q)uit
    new() if $key eq 'n';
}

Sample screen shot:


	Press direction arrows to move.

	Press q to quit. Press n for a new puzzle.

	┌──────┬──────┬──────┬──────┐
	│  2   │  1   │  10  │  14  │
	├──────┼──────┼──────┼──────┤
	│  15  │  11  │  12  │      │
	├──────┼──────┼──────┼──────┤
	│  13  │  3   │  6   │  7   │
	├──────┼──────┼──────┼──────┤
	│  9   │  4   │  5   │  8   │
	└──────┴──────┴──────┴──────┘

Phix

Kept simple. Obviously, increase the 5 random moves for more of a challenge.

constant ESC=27, UP=328, LEFT=331, RIGHT=333, DOWN=336
sequence board = tagset(15)&0, solve = board
integer pos = 16

procedure print_board()
    for i=1 to length(board) do
        puts(1,iff(i=pos?"   ":sprintf("%3d",{board[i]})))
        if mod(i,4)=0 then puts(1,"\n") end if
    end for
    puts(1,"\n")
end procedure

procedure move(integer d)
    integer new_pos = pos+{+4,+1,-1,-4}[d]
    if new_pos>=1 and new_pos<=16
    and (mod(pos,4)=mod(new_pos,4) -- same col, or row:
     or floor((pos-1)/4)=floor((new_pos-1)/4)) then
        {board[pos],board[new_pos]} = {board[new_pos],0}
        pos = new_pos
    end if
end procedure

for i=1 to 5 do move(rand(4)) end for
while 1 do
    print_board()
    if board=solve then exit end if
    integer c = find(wait_key(),{ESC,UP,LEFT,RIGHT,DOWN})-1
    if c=0 then exit end if
    move(c)
end while
puts(1,"solved!\n")

{{out}}


  1  2  3  4
  5     6  8
  9 10  7 11
 13 14 15 12

  1  2  3  4
  5  6     8
  9 10  7 11
 13 14 15 12

  1  2  3  4
  5  6  7  8
  9 10    11
 13 14 15 12

  1  2  3  4
  5  6  7  8
  9 10 11
 13 14 15 12

  1  2  3  4
  5  6  7  8
  9 10 11 12
 13 14 15

solved!

PureBasic

Console version. All Puzzles are solvable. #Difficulty is the number of shuffle (default 10). Numbers are displayed in Hexadecimal (ie 1 to F) Default controls are u,d,l,r


#difficulty=10 ;higher is harder
#up="u"
#down="d"
#left="l"
#right="r"
OpenConsole("15 game"):EnableGraphicalConsole(1)
Global Dim Game.i(3,3)
Global hole.point

Procedure NewBoard()
    num.i=0
    For j=0 To 3
        For i=0 To 3
            Game(i,j)=num
            num+1
        Next i
    Next j
EndProcedure
Procedure.s displayBoard()
    For j=0 To 3
        For i=0 To 3
            ConsoleLocate(i,j)
            If Game(i,j)=0:Print(" "):Continue:EndIf
            Print(Hex(Game(i,j)))
        Next i
    Next j
    PrintN("")
    Print("Your Choice Up :"+#up+", Down :"+#down+", Left :"+#left+" Or Right :"+#right+" ")
    Repeat
        keypress$=Inkey()
    Until keypress$<>""
    keypress$=LCase(keypress$)
    ProcedureReturn keypress$
EndProcedure
Procedure UpdateBoard(key$)
    If key$=#up And hole\y<3
        Swap game(hole\x,hole\y),game(hole\x,hole\y+1):hole\y+1
    ElseIf key$=#down And hole\y
        Swap game(hole\x,hole\y),game(hole\x,hole\y-1):hole\y-1
    ElseIf key$=#left And hole\x<3
        Swap game(hole\x,hole\y),game(hole\x+1,hole\y):hole\x+1
    ElseIf key$=#right And hole\x
        Swap game(hole\x,hole\y),game(hole\x-1,hole\y):hole\x-1
    EndIf
EndProcedure
Procedure TestGameWin()
    For j=0 To 3
        For i=0 To 3
            num+1
            If game(i,j)=num:win+1:EndIf
        Next i
    Next j
    If win=15:ProcedureReturn 1:EndIf
EndProcedure
Procedure ShuffleBoard(difficulty.i)
    Dim randomKey$(3)
    randomkey$(0)=#up:randomkey$(1)=#down:randomkey$(2)=#left:randomkey$(3)=#right
    For i=1 To difficulty
       UpdateBoard(randomKey$(Random(3)))
    Next i
EndProcedure
NewBoard()
ShuffleBoard(#difficulty)
Repeat
    choice$=displayBoard()
    UpdateBoard(choice$)
Until TestGameWin()
Print("Won !")
CloseConsole()


1234
5678
9ABC
DEF

Your Choice Up :u, Down :d, Left :l Or Right :r

Python

{{works with|Python|3.X}} '''unoptimized'''


''' Structural Game for 15 - Puzzle with different difficulty levels'''
from random import randint


class Puzzle:
    def __init__(self):
        self.items = {}
        self.position = None

    def main_frame(self):
        d = self.items
        print('+-----+-----+-----+-----+')
        print('|%s|%s|%s|%s|' % (d[1], d[2], d[3], d[4]))
        print('+-----+-----+-----+-----+')
        print('|%s|%s|%s|%s|' % (d[5], d[6], d[7], d[8]))
        print('+-----+-----+-----+-----+')
        print('|%s|%s|%s|%s|' % (d[9], d[10], d[11], d[12]))
        print('+-----+-----+-----+-----+')
        print('|%s|%s|%s|%s|' % (d[13], d[14], d[15], d[16]))
        print('+-----+-----+-----+-----+')

    def format(self, ch):
        ch = ch.strip()
        if len(ch) == 1:
            return '  ' + ch + '  '
        elif len(ch) == 2:
            return '  ' + ch + ' '
        elif len(ch) == 0:
            return '     '

    def change(self, to):
        fro = self.position
        for a, b in self.items.items():
            if b == self.format(str(to)):
                to = a
                break
        self.items[fro], self.items[to] = self.items[to], self.items[fro]
        self.position = to

    def build_board(self, difficulty):
        for i in range(1, 17):
            self.items[i] = self.format(str(i))
        tmp = 0
        for a, b in self.items.items():
            if b == '  16 ':
                self.items[a] = '     '
                tmp = a
                break
        self.position = tmp
        if difficulty == 0:
            diff = 10
        elif difficulty == 1:
            diff = 50
        else:
            diff = 100
        for _ in range(diff):
            lst = self.valid_moves()
            lst1 = []
            for j in lst:
                lst1.append(int(j.strip()))
            self.change(lst1[randint(0, len(lst1)-1)])

    def valid_moves(self):
        pos = self.position
        if pos in [6, 7, 10, 11]:
            return self.items[pos - 4], self.items[pos - 1],\
                   self.items[pos + 1], self.items[pos + 4]
        elif pos in [5, 9]:
            return self.items[pos - 4], self.items[pos + 4],\
                   self.items[pos + 1]
        elif pos in [8, 12]:
            return self.items[pos - 4], self.items[pos + 4],\
                   self.items[pos - 1]
        elif pos in [2, 3]:
            return self.items[pos - 1], self.items[pos + 1], self.items[pos + 4]
        elif pos in [14, 15]:
            return self.items[pos - 1], self.items[pos + 1],\
                  self.items[pos - 4]
        elif pos == 1:
            return self.items[pos + 1], self.items[pos + 4]
        elif pos == 4:
            return self.items[pos - 1], self.items[pos + 4]
        elif pos == 13:
            return self.items[pos + 1], self.items[pos - 4]
        elif pos == 16:
            return self.items[pos - 1], self.items[pos - 4]

    def game_over(self):
        flag = False
        for a, b in self.items.items():
            if b == '     ':
                pass
            else:
                if a == int(b.strip()):
                    flag = True
                else:
                    flag = False
        return flag


g = Puzzle()
g.build_board(int(input('Enter the difficulty : 0 1 2\n2 '
                        '=> highest 0=> lowest\n')))
g.main_frame()
print('Enter 0 to exit')
while True:
    print('Hello user:\nTo change the position just enter the no. near it')
    lst = g.valid_moves()
    lst1 = []
    for i in lst:
        lst1.append(int(i.strip()))
        print(i.strip(), '\t', end='')
    print()
    x = int(input())
    if x == 0:
        break
    elif x not in lst1:
        print('Wrong move')
    else:
        g.change(x)
    g.main_frame()
    if g.game_over():
        print('You WON')
        break


Enter the difficulty : 0 1 2
2 => highest 0=> lowest
1
+-----+-----+-----+-----+
|  1  |  7  |  2  |  4  |
+-----+-----+-----+-----+
|  5  |  6  |  3  |  12 |
+-----+-----+-----+-----+
|  9  |  8  |  11 |  15 |
+-----+-----+-----+-----+
|  13 |  10 |  14 |     |
+-----+-----+-----+-----+
Enter 0 to exit
Hello user:
To change the position just enter the no. near it
14 	15
14
+-----+-----+-----+-----+
|  1  |  7  |  2  |  4  |
+-----+-----+-----+-----+
|  5  |  6  |  3  |  12 |
+-----+-----+-----+-----+
|  9  |  8  |  11 |  15 |
+-----+-----+-----+-----+
|  13 |  10 |     |  14 |
+-----+-----+-----+-----+
Hello user:
To change the position just enter the no. near it
10 	14 	11

QB64


_TITLE "GUI Sliding Blocks Game "
RANDOMIZE TIMER

' get from user the desired board size = s
DO
    LOCATE CSRLIN, 3: INPUT "(0 quits) Enter your number of blocks per side 3 - 9 you want > ", s
    IF s = 0 THEN END
LOOP UNTIL s > 2 AND s < 10

' screen setup: based on the square blocks q pixels a sides
q = 540 / s 'square size, shoot for 540 x 540 pixel board display
SCREEN _NEWIMAGE(q * s + 1, q * s + 1, 32): _SCREENMOVE 360, 60

'initialize board = solution
DIM board(s, s)
FOR r = 1 TO s
    FOR c = 1 TO s
        board(c, r) = c + (r - 1) * s
    NEXT
NEXT
board(s, s) = 0: c0 = s: r0 = s

'scramble board for puzzle
FOR i = 0 TO s ^ 5 ' mix blocks
    SELECT CASE INT(RND * 4) + 1
        CASE 1: IF c0 < s THEN board(c0, r0) = board(c0 + 1, r0): board(c0 + 1, r0) = 0: c0 = c0 + 1
        CASE 2: IF c0 > 1 THEN board(c0, r0) = board(c0 - 1, r0): board(c0 - 1, r0) = 0: c0 = c0 - 1
        CASE 3: IF r0 < s THEN board(c0, r0) = board(c0, r0 + 1): board(c0, r0 + 1) = 0: r0 = r0 + 1
        CASE 4: IF r0 > 1 THEN board(c0, r0) = board(c0, r0 - 1): board(c0, r0 - 1) = 0: r0 = r0 - 1
    END SELECT
NEXT

t = TIMER: update = -1 'OK user here you go!
DO
    IF update THEN 'display status and determine if solved
        solved = -1: update = 0
        FOR r = 1 TO s
            FOR c = 1 TO s
                IF board(c, r) THEN
                    IF board(c, r) <> (r - 1) * s + c THEN solved = 0
                    COLOR _RGB32(255, 255, 255), _RGB32(0, 0, 255)
                    LINE ((c - 1) * q + 1, (r - 1) * q + 2)-(c * q - 2, r * q - 2), _RGB32(0, 0, 255), BF
                    _PRINTSTRING ((c - 1) * q + .4 * q, (r - 1) * q + .4 * q), RIGHT$(" " + STR$(board(c, r)), 2)
                ELSE
                    IF board(s, s) <> 0 THEN solved = 0
                    COLOR _RGB32(0, 0, 0), _RGB32(0, 0, 0)
                    LINE ((c - 1) * q, (r - 1) * q)-(c * q, r * q), , BF
                END IF
            NEXT
        NEXT
        IF solved THEN 'flash the Solved Report until user closes window else report status
            _DISPLAY
            flash$ = "Solved!" + STR$(mc) + " Moves in " + STR$(INT(TIMER - t)) + " secs."
            WHILE 1: _TITLE flash$: _DELAY .2: _TITLE "  ": _DELAY .2: WEND
        ELSE
            _TITLE STR$(mc) + " Moves in " + STR$(INT(TIMER - t)) + " secs." + STR$(test)
        END IF
        _DISPLAY
    END IF

    'get next mouse click, check if on block next to empty space make move or beep
    m = _MOUSEINPUT: mb = _MOUSEBUTTON(1): mx = _MOUSEX: my = _MOUSEY
    IF mb AND solved = 0 THEN 'get last place mouse button was down
        mb = _MOUSEBUTTON(1): mx = _MOUSEX: my = _MOUSEY
        WHILE mb 'left button down, wait for mouse button release
            m = _MOUSEINPUT: mb = _MOUSEBUTTON(1): mx = _MOUSEX: my = _MOUSEY
        WEND

        'convert mouse position to board array (x, y) are we near empty space?
        bx = INT(mx / q) + 1: by = INT(my / q) + 1: update = -1
        IF bx = c0 + 1 AND by = r0 THEN
            board(c0, r0) = board(c0 + 1, r0): board(c0 + 1, r0) = 0: c0 = c0 + 1: mc = mc + 1
        ELSEIF bx = c0 - 1 AND by = r0 THEN
            board(c0, r0) = board(c0 - 1, r0): board(c0 - 1, r0) = 0: c0 = c0 - 1: mc = mc + 1
        ELSEIF bx = c0 AND by = r0 + 1 THEN
            board(c0, r0) = board(c0, r0 + 1): board(c0, r0 + 1) = 0: r0 = r0 + 1: mc = mc + 1
        ELSEIF bx = c0 AND by = r0 - 1 THEN
            board(c0, r0) = board(c0, r0 - 1): board(c0, r0 - 1) = 0: r0 = r0 - 1: mc = mc + 1
        ELSE
            BEEP
        END IF
    END IF
LOOP

R

The inputs are w,a,s,d and they refer to the direction in which the adjacent piece moves into the empty space. For example, on a solved puzzle, "d" would move the 15 to the right.


puz15<-function(scramble.length=100){
  m=matrix(c(1:15,0),byrow=T,ncol=4)
  scramble=sample(c("w","a","s","d"),scramble.length,replace=T)
  for(i in 1:scramble.length){
    m=move(m,scramble[i])
  }
  win=F
  turn=0
  while(!win){
    print.puz(m)
    newmove=getmove()
    if(newmove=="w"|newmove=="a"|newmove=="s"|newmove=="d"){
      m=move(m,newmove)
      turn=turn+1
    }
    else{
      cat("Input not recognized","\n")
    }
    if(!(F %in% m==matrix(c(1:15,0),byrow=T,ncol=4))){
      win=T
    }
  }
  print.puz(m)
  cat("\n")
  print("You win!")
  cat("\n","It took you",turn,"moves.","\n")
}

getmove<-function(){
  direction<-readline(prompt="Move:")
  return(direction)
}
move<-function(m,direction){
  if(direction=="w"){
    m=move.u(m)
  }
  else if(direction=="s"){
    m=move.d(m)
  }
  else if(direction=="a"){
    m=move.l(m)
  }
  else if(direction=="d"){
    m=move.r(m)
  }
  return(m)
}
move.u<-function(m){
  if(0 %in% m[4,]){}
  else{
    pos=which(m==0)
    m[pos]=m[pos+1]
    m[pos+1]=0
  }
  return(m)
}
move.d<-function(m){
  if(0 %in% m[1,]){}
  else{
    pos=which(m==0)
    m[pos]=m[pos-1]
    m[pos-1]=0
  }
  return(m)
}
move.l<-function(m){
  if(0 %in% m[,4]){return(m)}
  else{return(t(move.u(t(m))))}
}
move.r<-function(m){
  if(0 %in% m[,1]){return(m)}
  else{return(t(move.d(t(m))))}
}
print.puz<-function(m){
  cat("+----+----+----+----+","\n")
  for(r in 1:4){
    string="|"
    for(c in 1:4){
      if(m[r,c]==0)
        string=paste(string,"    |",sep="")
      else if(m[r,c]<10)
        string=paste(string,"  ",m[r,c]," |",sep="")
      else
        string=paste(string," ",m[r,c]," |",sep="")
    }
    cat(string,"\n","+----+----+----+----+","\n",sep="")
  }
}

Sample output:


> puz15(scramble.length=4)
+----+----+----+----+
|  1 |  2 |  3 |  4 |
+----+----+----+----+
|  5 |  6 |  7 |  8 |
+----+----+----+----+
|  9 | 10 |    | 12 |
+----+----+----+----+
| 13 | 14 | 11 | 15 |
+----+----+----+----+
Move:w
+----+----+----+----+
|  1 |  2 |  3 |  4 |
+----+----+----+----+
|  5 |  6 |  7 |  8 |
+----+----+----+----+
|  9 | 10 | 11 | 12 |
+----+----+----+----+
| 13 | 14 |    | 15 |
+----+----+----+----+
Move:a
+----+----+----+----+
|  1 |  2 |  3 |  4 |
+----+----+----+----+
|  5 |  6 |  7 |  8 |
+----+----+----+----+
|  9 | 10 | 11 | 12 |
+----+----+----+----+
| 13 | 14 | 15 |    |
+----+----+----+----+

[1] "You win!"

 It took you 2 moves.

Racket

This is a GUI game; and there are difficulties getting screen shots onto RC. Use the arrow keys to slide the ''blank'' square.

It uses the 2htdp/universe package.

#lang racket/base
(require 2htdp/universe 2htdp/image racket/list racket/match)

(define ((fifteen->pict (finished? #f)) fifteen)
  (for/fold ((i (empty-scene 0 0))) ((r 4))
    (define row
      (for/fold ((i (empty-scene 0 0))) ((c 4))
        (define v (list-ref fifteen (+ (* r 4) c)))
        (define cell
          (if v
              (overlay/align
               "center" "center"
               (rectangle 50 50 'outline (if finished? "white" "blue"))
               (text (number->string v) 30 "black"))
              (rectangle 50 50 'solid (if finished? "white" "powderblue"))))
        (beside i cell)))
    (above i row)))

(define (move-space fifteen direction)
  (define idx (for/first ((i (in-naturals)) (x fifteen) #:unless x) i))
  (define-values (row col) (quotient/remainder idx 4))
  (define dest (+ idx (match direction
                        ['l #:when (> col 0) -1]
                        ['r #:when (< col 3)  1]
                        ['u #:when (> row 0) -4]
                        ['d #:when (< row 3)  4]
                        [else 0])))
    (list-set (list-set fifteen idx (list-ref fifteen dest)) dest #f))

(define (key-move-space fifteen a-key)
  (cond [(key=? a-key "left") (move-space fifteen 'l)]
        [(key=? a-key "right") (move-space fifteen 'r)]
        [(key=? a-key "up") (move-space fifteen 'u)]
        [(key=? a-key "down") (move-space fifteen 'd)]
        [else fifteen]))

(define (shuffle-15 fifteen shuffles)
  (for/fold ((rv fifteen)) ((_ shuffles))
    (move-space rv (list-ref '(u d l r) (random 4)))))

(define fifteen0 '(1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 #f))

(define (solved-world? w) (equal? w fifteen0))

(big-bang (shuffle-15 fifteen0 200)
          (name "Fifteen")
          (to-draw (fifteen->pict))
          (stop-when solved-world? (fifteen->pict #t))
          (on-key key-move-space))

Rebol

rebol []  random/seed now  g: [style t box red [
  if not find [0x108 108x0 0x-108 -108x0] face/offset - e/offset [exit]
  x: face/offset face/offset: e/offset e/offset: x] across
] x: random repeat i 15 [append x:[] i]  repeat i 15 [
  repend g ['t mold x/:i random white] if find [4 8 12] i [append g 'return]
] append g [e: box]  view layout g

REXX

This REXX version allows the user to specify the size of the puzzle ('''N''', where '''NxN''' is the size of the puzzle).

With some more complexity, the REXX computer program could be changed to allow multiple-tile moves (so that, for instance, three tiles could be slid to the right).

Over half of the REXX program has to do with input validation and presentation of the puzzle (grid).

/*REXX pgm implements the 15─puzzle (AKA: Gem Puzzle, Boss Puzzle, Mystic Square, 14─15)*/
parse arg N seed .                               /*obtain optional arguments from the CL*/
if N=='' | N==","  then N=4                      /*Not specified?  Then use the default.*/
if datatype(seed, 'W')  then call random ,,seed  /*use repeatability seed for RANDOM BIF*/
nh= N**2;   @.=;    nn= nh - 1;    w= length(nn) /*define/initialize some handy values. */
$=                                               /*$: will hold the solution for testing*/
       do i=1  for nn;  $= $  i                  /* [◄]  build a solution for testing.  */
       end   /*i*/
done=$                                           /* [↓]  scramble the tiles in puzzle.  */
       do j=1  for nn;  a= random(1, words($) );    @.j= word($, a);   $= delword($, a, 1)
       end   /*j*/
/*════════════════════════════════════════════════ play the 15─puzzle 'til done or quit.*/
   do  until puzz==done & @.nh==''               /*perform moves until puzzle is solved.*/
   call getmv                                    /*get user's move(s)  and  validate it.*/
   if errMsg\==''  then do;  say sep errMsg;       iterate        /*possible error msg? */
                        end
   call showGrid 0                               /*don't display puzzle, just find hole.*/
   if wordpos(x, !)==0  then do;  say sep  'tile '     x     " can't be moved.";   iterate
                             end
   @.hole= x;    @.tile=
   call showGrid 0                               /*move specified tile ───► puzzle hole.*/
   end   /*until*/

call showGrid 1;    say;     say sep  'Congratulations!   The'      nn"-puzzle is solved."
exit                                             /*stick a fork in it,  we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
getmv: x=0;    sep= copies('─', 8);     pad= left('', 1 + length(sep) )   /*pad=9 blanks*/
       prompt= sep    'Please enter a tile number  or  numbers '     sep     " (or Quit)."
       if queued()==0  then do;    say;    call showGrid 1;     say;      say prompt
                            end
       parse pull x . 1 ox . 1 . zx;   upper x   /*obtain a number (or numbers) from CL.*/
       if abbrev('QUIT', x, 1)  then do;   say;   say;    say sep  "quitting.";      exit
                                     end
       if words(zx)>0  then do;  parse var  zx    xq;     queue xq
                            end                  /* [↑]  Extra moves?  Stack for later. */
              select                             /* [↓]  Check for possible errors/typos*/
              when x==''              then errMsg= "nothing entered."
              when \datatype(x, 'N')  then errMsg= "tile number isn't numeric: "        ox
              when \datatype(x, 'W')  then errMsg= "tile number isn't an integer: "     ox
              when x=0                then errMsg= "tile number can't be zero: "        ox
              when x<0                then errMsg= "tile number can't be negative: "    ox
              when x>nn               then errMsg= "tile number can't be greater than"  nn
              otherwise                    errMsg=
              end   /*select*/                   /* [↑]  verify the human entered data. */
       return
/*──────────────────────────────────────────────────────────────────────────────────────*/
showGrid: parse arg show;       !.=;                      x= x/1;       #= 0;        puzz=
          top= '╔'copies( copies("═", w)'╦', N);        top= left( top, length(top) -1)"╗"
          bar= '╠'copies( copies("═", w)'╬', N);        bar= left( bar, length(bar) -1)"╣"
          bot= '╚'copies( copies("═", w)'╩', N);        bot= left( bot, length(bot) -1)"╝"
          if show  then say pad top

               do   r=1  for N;     z= '║'
                 do c=1  for N;     #= #+1;     y= @.#;      puzz= puzz y;        !.r.c= y
                 _= right(@.#, w)"║";           z= z || _              /* [↓]  find hole*/
                 if @.# == ''  then do;    hole= #;     holeRow= r;     holeCol= c;    end
                 if @.# == x   then do;    tile= #;     tileRow= r;     tileCol= c;    end
                 end   /*c*/                                           /* [↑]  find  X. */
               if show  then do;    say pad z;     if r\==N  then say pad bar;         end
               end     /*r*/

          rm=holeRow-1;   rp=holeRow+1;  cm=holeCol-1;  cp=holeCol+1   /*possible moves.*/
          !=!.rm.holeCol  !.rp.holeCol   !.holeRow.cm   !.holeRow.cp   /* legal   moves.*/
          if show  then say pad bot;                  return

{{out|output|text= when using the default input:}}


           ╔══╦══╦══╦══╗
           ║10║ 7║ 8║11║
           ╠══╬══╬══╬══╣
           ║ 4║ 3║15║ 1║
           ╠══╬══╬══╬══╣
           ║ 9║12║ 2║13║
           ╠══╬══╬══╬══╣
           ║14║ 5║ 6║  ║
           ╚══╩══╩══╩══╝

──────── Please enter a tile number  or  numbers  ────────  (or Quit).
13                           ◄■■■■■■■■■■ user input.
           ╔══╦══╦══╦══╗
           ║10║ 7║ 8║11║
           ╠══╬══╬══╬══╣
           ║ 4║ 3║15║ 1║
           ╠══╬══╬══╬══╣
           ║ 9║12║ 2║  ║
           ╠══╬══╬══╬══╣
           ║14║ 5║ 6║13║
           ╚══╩══╩══╩══╝

──────── Please enter a tile number  or  numbers  ────────  (or Quit).
1  15  3                     ◄■■■■■■■■■■ user input.
           ╔══╦══╦══╦══╗
           ║10║ 7║ 8║11║
           ╠══╬══╬══╬══╣
           ║ 4║  ║ 3║15║
           ╠══╬══╬══╬══╣
           ║ 9║12║ 2║ 1║
           ╠══╬══╬══╬══╣
           ║14║ 5║ 6║13║
           ╚══╩══╩══╩══╝

──────── Please enter a tile number  or  numbers  ────────  (or Quit).
quit                         ◄■■■■■■■■■■ user input.


──────── quitting.

Ring

CalmoSoft [[wp:15_puzzle|Fifteen Puzzle Game]] written in Ring Programming Language (http://ring-lang.net)

Video: [https://www.google.com/url?q=https%3A%2F%2F1drv.ms%2Fv%2Fs!AqDUIunCqVnIg0J6sL9df0JcV2TY&sa=D&sntz=1&usg=AFQjCNEFaWD8AqElMZK3KGnRKDhKxCO1Sw CalmoSoft Fifteen Puzzle Game Video]

Output Image: [https://1drv.ms/i/s!AqDUIunCqVnIg0zg_d-lOM8CfLdM CalmoSoft Fifteen Puzzle Game Image]

The code:

# Project : CalmoSoft Fifteen Puzzle Game (Under Development)

load "guilib.ring"

app1 = new qapp {

        stylefusionblack()
        empty = 16
        nrMoves = 0
        nrSleep = 1
        butSize = 4
        curBut = 4
        temp = 0
        flaginit = 0
        flagsave = 0
        flagmove = 0
        button = list(52)
        sizebtn = list(7)
        table1 = []
        table2 = []
        table3 = []
        nDegree = 0
        nrDegree = [0,90,180,270 ,-90,-180,-270]
        nDegreeRight = 0
        nDegreeLeft = 0
        btnDegree = newlist(52,2)
        CounterMan = 0
        t1 = 0

        win1 = new qwidget() {
                   move(0,0)
                   resize(380,760)
                   setwindowtitle("CalmoSoft Fifteen Puzzle Game")

                  for n=1 to 52
                        for m=1 to 2
                             btnDegree[n][m] = 0
                        next
                  next

                   for n = 4 to 7
                               sizebtn[n] = new qpushbutton(win1)
                               {
                                                  col = n%4
                                                  setgeometry(100+col*40,60,40,40)
                                                  settext(string(n) + "x" + string(n))
                                                  setclickevent("newsize(" + string(n) + ")")
                               }
                   next

                  btnMoves = new qpushbutton(win1)
                  {
                                 setgeometry(100,260,80,40)
                                 settext("0")
                                 show()
                  }

                   scramblebtn = new qpushbutton(win1)
                   {
                                         setgeometry(100,300,160,40)
                                         settext("Scramble")
                                         setclickevent("scramble()")
                   }

                   resetbtn = new qpushbutton(win1)
                   {
                                    setgeometry(100,340,160,40)
                                    settext("Reset")
                                    setclickevent("resettiles()")
                   }

                   savebtn = new qpushbutton(win1)
                   {
                                   setgeometry(100,380,160,40)
                                   settext("Save Game")
                                   setclickevent("pSave()")
                   }

                   playbtn = new qpushbutton(win1)
                   {
                                   setgeometry(100,420,160,40)
                                   settext("Resume Game")
                                   setclickevent("pPlay()")
                   }

                   sleepbtn = new qpushbutton(win1)
                   {
                                   setgeometry(100,460,160,40)
                                   settext("Sleep Time: ")

                   }

                  decbtn = new qpushbutton(win1)
                  {
                               setgeometry(220,460,40,40)
                               settext("<-")
                               setclickevent("pDecSleep()")
                  }

                  incbtn = new qpushbutton(win1)
                  {
                               setgeometry(260,460,40,40)
                               settext("->")
                               setclickevent("pIncSleep()")
                  }

                 rightbtn = new qpushbutton(win1)
                 {
                               setgeometry(100,500,160,40)
                               settext("In the Right Place : ")
                 }

                 timebtn = new qpushbutton(win1)
                 {
                               setgeometry(100,540,160,40)
                               settext("Elapsed Time : ")
                 }

                TimerMan = new qtimer(win1)
               {
                                  setinterval(500)
                                  settimeoutevent("pTime()")
                                  stop()
               }
              newsize(4)
              show()
        }
        exec()
}

Func newlist x, y
     if isstring(x) x=0+x ok
     if isstring(y) y=0+y ok
     alist = list(x)
     for t in alist
         t = list(y)
     next
     return alist

func scramble
       for n= 1 to 1000
            curBut=random(butSize*butSize-1)+1
            up = (empty = (curBut - butSize))
            down = (empty = (curBut + butSize))
            left = ((empty = (curBut - 1)) and ((curBut % butSize) != 1))
            right = ((empty = (curBut + 1)) and ((curBut % butSize) != 0))
            move = up or down or left  or right
            if move = 1
               button[curBut] { temp2 = text() }
               col = empty%butSize
               if col = 0 col = butSize ok
               row = ceil(empty/butSize)
               button[empty] {
                       setgeometry(60+col*40,60+row*40,40,40)
                       rnd = random(6)+1
                       nDegree = nrDegree[rnd]
                       button[empty].setbuttoncolor("yellow")
                       button[empty].settext(temp2)
                       button[empty].setClickEvent("movetile(" + string(empty) +")")
                       btnDegree[empty] [1] = temp2
                       btnDegree[empty] [2] = nDegree
                       }
               button[curBut].setbuttoncolor("yellow")
               btnDegree[curBut][2] = 0
               button[curBut]{settext("")}
               empty = curBut
            ok
       next
       button[butSize*butSize+2]{settext("Here")}
       for n=1 to butSize*butSize
             button[n].setbuttoncolor("yellow")
       next
       table1 = []
       table2 = []
       table3 = []
       for n = 1 to butSize*butSize
             add(table1, button[n].text())
             add(table2, button[n].text())
             add(table3, string(btnDegree[n][2]))
       next
       add(table1, string(empty))
       add(table2, string(empty))
       add(table3, string(empty))
       add(table1, "OK")
       add(table2, "OK")
       add(table3, "OK")
       flagsave = 0
       flagmove = 0
       nrMoves = 0
       btnMoves.settext(string(nrMoves))
       timebtn.settext("Elapsed Time : ")
       t1 = clock()
       rightPlace()
       return

func movetile curBut2
       if (curBut2 = butSize*butSize-1 and button[curBut2].text() = "In")
           pBack()
       else
           see char(7)
           up = (empty = (curBut2 - butSize))
           down = (empty = (curBut2 + butSize))
           left = ((empty = (curBut2- 1)) and ((curBut2 % butSize) != 1))
           right = ((empty = (curBut2 + 1)) and ((curBut2 % butSize) != 0))
           move = up or down or left  or right
           if move = 1
              temp2 = button[curBut2].text()
              btnDegree[empty][1] = temp2
              add(table1, temp2)
              add(table2, string(curBut2))
              col = empty%butSize
              if col = 0 col = butSize ok
              row = ceil(empty/butSize)
              button[empty] {
                                   setgeometry(60+col*40,60+row*40,40,40)
                                   nDegree = btnDegree[curBut2][2]
                                   btnDegree[empty][2] = nDegree
                                   button[empty].setbuttoncolor("orange")
                                   button[empty].settext(temp2)
              }
              add(table3, string(nDegree))
              button[curBut2].setbuttoncolor("cyan")
              button[curBut2]{settext("")}
              empty = curBut2
              nrMoves = nrMoves + 1
              btnMoves.settext(string(nrMoves))
              isGameOver()
           ok
      ok
      flagmove = 1
      pElapsedTime()
      rightPlace()
      return

func resettiles
        nDegree = 0
        empty = butSize*butSize
        for empty = 1 to butSize*butSize-1
             btnDegree[empty][2] = 0
             nDegree = 0
             btnDegree[empty][1] = string(empty)
             button[empty].setstylesheet("background-color:yellow")
             button[empty] {settext(string(empty))}
        next
        button[butSize*butSize].setstylesheet("background-color:yellow")
        button[butSize*butSize] {settext("")}
        table1 = []
        table2 = []
        table3 = []
        for n = 1 to butSize*butSize
             add(table1, button[n].text())
             add(table2, button[n].text())
             add(table3, string(btnDegree[n][2]))
        next
        add(table1, string(empty))
        add(table2, string(empty))
        add(table3, string(empty))
        add(table1, "OK")
        add(table2, "OK")
        add(table3, "OK")
        flagsave = 0
        flagmove = 0
        nrMoves = 0
        btnMoves.settext(string(nrMoves))
        timebtn.settext("Elapsed Time : ")
        t1 = clock()
        rightPlace()
        return

func pHere
        if button[butSize*butSize-1].text() != "" and button[butSize*butSize+2].text() = "Here"
           button[butSize*butSize-1] { temp = text() }
           button[butSize*butSize+2].close()
           button[butSize*butSize+2] = new ButtonWithRotatedText(win1)
           button[butSize*butSize+2] {
           setgeometry(60+(butSize-1)*40,60+(butSize+1)*40,40,40)
           setstylesheet("background-color:yellow")
           btnDegree[butSize*butSize+2][2] = btnDegree[butSize*butSize-1][2]
           nDegree = btnDegree[butSize*butSize+2][2]
           emptysave = empty
           empty = butSize*butSize+2
           btnDegree[empty][1] = temp
           settext(temp)
           }
           nDegree = 0
           empty = butSize*butSize-1
           btnDegree[empty][1] = "In"
           button[butSize*butSize-1]{settext("In")}
           for n = 1 to butSize*butSize
	   button[n].setenabled(false)
           next
           button[butSize*butSize-1].setenabled(true)
           scramblebtn.setenabled(false)
           resetbtn.setenabled(false)
           savebtn.setenabled(false)
           playbtn.setenabled(false)
           empty = emptysave
        ok

func pBack
        button[butSize*butSize+2] { temp = text() }
        nDegree = btnDegree[butSize*butSize+2][2]
        btnDegree[butSize*butSize-1][2] = btnDegree[butSize*butSize+2][2]
        emptysave = empty
        empty = butSize*butSize-1
        btnDegree[empty][1] = temp
        button[butSize*butSize-1] {settext(temp)}
        button[butSize*butSize+2].close()
        button[butSize*butSize+2] = new qpushbutton(win1)
                {
                setgeometry(60+(butSize-1)*40,60+(butSize+1)*40,40,40)
                settext("Here")
                setclickevent("pHere()")
                show()
                }
        for n = 1 to butSize*butSize
              button[n].setenabled(true)
        next
        scramblebtn.setenabled(true)
        resetbtn.setenabled(true)
        savebtn.setenabled(true)
        playbtn.setenabled(true)
        empty = emptysave
        isGameOver()

func rotateleft
        if button[butSize*butSize+2].text() != "Here"
           button[butSize*butSize+2].close()
           button[butSize*butSize+2] = new ButtonWithRotatedText(win1)
                      button[butSize*butSize+2] {
                      setgeometry(60+(butSize-1)*40,60+(butSize+1)*40,40,40)
                      setstylesheet("background-color:yellow")
                      nDegreeLeft = (nDegreeLeft-90)%360
                      nDegree = nDegreeLeft
                      btnDegree[butSize*butSize+2][2] = nDegree
                      emptysave = empty
                      empty = butSize*butSize+2
                      btnDegree[empty][1] = temp
                      button[butSize*butSize+2]{settext(temp)}
                      }
                      empty = emptysave
        ok

func rotateright
        if button[butSize*butSize+2].text() != "Here"
           button[butSize*butSize+2].close()
           button[butSize*butSize+2] = new ButtonWithRotatedText(win1)
                      button[butSize*butSize+2] {
                      setgeometry(60+(butSize-1)*40,60+(butSize+1)*40,40,40)
                      setstylesheet("background-color:yellow")
                      nDegreeRight = (nDegreeRight+90)%360
                      nDegree = nDegreeRight
                      btnDegree[butSize*butSize+2][2] = nDegree
                      emptysave = empty
                      empty = butSize*butSize+2
                      btnDegree[empty][1] = temp
                      button[butSize*butSize+2]{settext(temp)}
                      }
                      empty = emptysave
        ok

func newsize curBut
        win1{
                sizenew = curBut%4
                win1.resize(360+sizenew*40,640+sizenew*40)
                if flaginit != 0
                   for nb = 1 to butSize*butSize+3
                         button[nb] {close()}
                   next
                   btnMoves.close()
                ok
                scramblebtn.close()
                resetbtn.close()
                savebtn.close()
                playbtn.close()
                btnMoves.close()
                sleepbtn.close()
                decbtn.close()
                incbtn.close()
                rightbtn.close()
                timebtn.close()

                for n = 1 to curBut*curBut
                     col = n%curBut
                     if col = 0 col = curBut ok
                     row = ceil(n/curBut)
                     button[n] = new ButtonWithRotatedText(win1)
                                       button[n] {
                                       setgeometry(60+col*40,60+row*40,40,40)
                                       button[n].setbuttoncolor("yellow")
                                       nDegree = 0
                                       if n < curBut*curBut
                                          button[n].settext(string(n))
                                       but n = curBut*curBut
                                          button[n].settext("")
                                       ok
                                       setClickEvent("movetile(" + string(n) +")")
                                       }
                next

                btnMoves = new qpushbutton(win1)
                {
                                        setgeometry(100,60+(curBut+1)*40,(curBut-3)*40,40)
                                        setStyleSheet("text-align:center")
                                        settext("0")
                                        show()
                }

                button[curBut*curBut+1] = new qpushbutton(win1)
                {
                                              setgeometry(60+(curBut-2)*40,60+(curBut+1)*40,40,40)
                                              settext("<-")
                                              setclickevent("rotateLeft()")
                                              show()
                }

                button[curBut*curBut+2] = new qpushbutton(win1)
                {
                                             setgeometry(60+(curBut-1)*40,60+(curBut+1)*40,40,40)
                                             settext("Here")
                                             setclickevent("pHere()")
                                             show()
                }

                button[curBut*curBut+3] = new qpushbutton(win1)
                {
                                             setgeometry(60+curBut*40,60+(curBut+1)*40,40,40)
                                             settext("->")
                                             setclickevent("rotateRight()")
                                             show()
                 }

                scramblebtn = new qpushbutton(win1)
                {
                                      setgeometry(100,100+(curBut+1)*40,curBut*40,40)
                                      settext("Scramble")
                                      setclickevent("scramble()")
                                      show()
                }

                resetbtn = new qpushbutton(win1)
                {
                                 setgeometry(100,100+(curBut+2)*40,curBut*40,40)
                                 settext("Reset")
                                 setclickevent("resettiles()")
                                 show()
                }

                savebtn = new qpushbutton(win1)
                {
                                 setgeometry(100,100+(curBut+3)*40,curBut*40,40)
                                 settext("Save Game")
                                 setclickevent("pSave()")
                                 show()
                }

                playbtn = new qpushbutton(win1)
                {
                               setgeometry(100,100+(curBut+4)*40,curBut*40,40)
                               settext("Resume Game")
                               setclickevent("pPlay()")
                               show()
                }

                sleepbtn = new qpushbutton(win1)
                {
                               setgeometry(100,100+(curBut+5)*40,(curBut-2)*40,40)
                               settext("Sleep Time: " + string(nrSleep) + " s")
                               show()
                }

                decbtn = new qpushbutton(win1)
                {
                               setgeometry(100+(curBut-2)*40,100+(curBut+5)*40,40,40)
                               settext("<-")
                               setclickevent("pDecSleep()")
                               show()
                }

                incbtn = new qpushbutton(win1)
                {
                               setgeometry(100+(curBut-1)*40,100+(curBut+5)*40,40,40)
                               settext("->")
                               setclickevent("pIncSleep()")
                               show()
                }

               rightbtn = new qpushbutton(win1)
                {
                               setgeometry(100,100+(curBut+6)*40,curBut*40,40)
                               settext("In the Right Place : ")
                               show()
                }

                timebtn = new qpushbutton(win1)
                {
                               setgeometry(100,100+(curBut+7)*40,curBut*40,40)
                               settext("Elapsed Time : ")
                               show()
                }

                table1 = []
                table2 = []
                table3 = []
                for n = 1 to butSize*butSize
                      add(table1, button[n].text())
                      add(table2, button[n].text())
                      add(table3, string(0))
                next
                add(table1, string(empty))
                add(table2, string(empty))
                add(table3, string(empty))
                add(table1, "OK")
                add(table2, "OK")
                add(table3, "OK")
                empty = curBut*curBut
                butSize = curBut
                flaginit = 1
                flagsave = 0
                flagmove = 0
                nrMoves = 0
                timebtn.settext("Elapsed Time : ")
                t1 = clock()
                scramble()
                }

func pSave
        textedit1 = list2str(table1)
        textedit2 = list2str(table2)
        textedit3 = list2str(table3)
        chdir(currentdir())
        cName1 = "CalmoSoftPuzzle1.txt"
        cName2 = "CalmoSoftPuzzle2.txt"
        cName3 = "CalmoSoftPuzzle3.txt"
        write(cName1,textedit1)
        write(cName2,textedit2)
        write(cName3,textedit3)
         flagsave = 1
         timebtn.settext("Elapsed Time : ")
         t1 = clock()
         return

func pPlay
        if  flagsave = 0 or flagmove = 0
            warning()
        else
           chdir(currentdir())
           cName1 = "CalmoSoftPuzzle1.txt"
           textedit1 = read(cName1)
           table1 = str2list(textedit1)
           cName2 = "CalmoSoftPuzzle2.txt"
           textedit2 = read(cName2)
           table2 = str2list(textedit2)
           cName3 = "CalmoSoftPuzzle3.txt"
           textedit3 = read(cName3)
           table3 = str2list(textedit3)
           for empty = 1 to butSize*butSize
                button[empty].setbuttoncolor("yellow")
                nDegree = number(table3[empty])
                btnDegree[empty][1] = table1[empty]
                button[empty] {settext(table1[empty])}
           next
           empty = number(table1[butSize*butSize + 1])
           CounterMan = butSize*butSize+2
           nrMoves = 0
           t1 = clock()
           TimerMan.start()
       ok

func pTime()
        if flagsave = 0 or flagmove = 0
           warning()
        else
           CounterMan++
           pPlaySleep()
           sleep(nrSleep*1000)
           pElapsedTime()
           if CounterMan = len(table1)
              TimerMan.stop()
           ok
        ok

func pPlaySleep
        see char(7)
        value = table1[CounterMan]
        place = table2[CounterMan]
        nDegree = number(table3[CounterMan])
        btnDegree[empty][1] = value
        button[empty].setbuttoncolor("orange")
        button[empty] {settext(value)}
        nDegree = 0
        button[number(place)].setbuttoncolor("cyan")
        button[number(place)] {settext("")}
        empty = number(place)
        nrMoves = nrMoves + 1
        btnMoves.settext(string(nrMoves))

func pIncSleep
        nrSleep = nrSleep + 1
        sleepbtn.settext("Sleep Time: " + string(nrSleep) + " s")

func pDecSleep
        if nrSleep > 1
           nrSleep = nrSleep - 1
           sleepbtn.settext("Sleep Time: " + string(nrSleep) + " s")
        ok

func sleep(x)
        nTime = x
        oTest = new qTest
        oTest.qsleep(nTime)
        return

func isGameOver
        flagend = 1
        for n=1 to butSize*butSize-1
              if button[n].text() != n or btnDegree[n][2] != 0
                 flagend = 0
                 exit
              ok
        next
        if flagend = 1
           new qmessagebox(win1) {
                   setwindowtitle("Game Over")
                   settext("Congratulations!")
                   show()
                   }
        ok

func rightPlace
        count = 0
        for n=1 to butSize*butSize
             if button[n].text() = n and btnDegree[n][2] = 0
                count = count + 1
             ok
        next
        rightbtn.settext("In the Right Place : " + count)

func warning
        new qmessagebox(win1) {
                setwindowtitle("Warning!")
                settext("First you must play and save the game.")
                show()
                }

func pElapsedTime
        t2 = (clock() - t1)/1000
        timebtn.settext("Elapsed Time : " + t2 + " s")

Class ButtonWithRotatedText

         oButton oLabel  cText="We are here"  nDegree = 30  nTransX = 50   nTransY = 0

func init( oParent)
        oButton = new qPushButton(oParent)
        oLabel  = new qLabel(oParent)
        oLabel.setAttribute(Qt_WA_TransparentForMouseEvents,True)
        oLabel.setAttribute(Qt_WA_DeleteOnClose, True)
        oButton.setAttribute(Qt_WA_DeleteOnClose, True)
        oButton.Show()
        return

func close()
        oLabel.close()
        oButton.close()
        return

func setstylesheet(x)
        oButton.setstylesheet(x)

func setgeometry( x,y,width,height)
        oButton.setgeometry(x,y,width,height)
        oLabel.setgeometry( x,y,width,height)

func setText( cValue)
        cText = cValue
        return

func Text()
         return cText

func setTranslate( x,y )
         nTransX = x
         nTransY = y
         return

func TranslateOffsetX()
        return nTransX

func TranslateOffsetY()
        return nTransY

func setRotationDegree( nValue)
        nDegree = nValue
        return

func RotationDegree()
        return nDegree

func setClickEvent( cEvent)
        oButton.setClickEvent(cEvent)
        return

func braceend()
        draw()
        return

func setEnabled(value)
        oButton.setenabled(value)
        return

 func setButtonColor(color)
         colorIt = "background-color:" + color
         oButton.setstylesheet(colorIt)
         return

func draw()
         picture = new qpicture()
         color   = new qcolor() { setrgb(0,0,255,255) }
         pen     = new qpen()   { setcolor(color) setwidth(10) }

         painter = new qpainter()
         {
                       begin(picture)
                       setpen(pen)
                       oFont = new qfont("Courier New",12,75,0)
                       oFont.setpointsize(20)
                       setfont(oFont)
                       if nDegree = 0
                          if btnDegree[empty] [1]="In" p1 = -8 p2=0
                          translate(p1,p2) ok ok
                       if nDegree = 0
                          if btnDegree[empty] [1]<10 p1 = 10 p2=10 else p1=5 p2=10 ok
                          translate(p1,p2)
                       but nDegree = 90
                             if btnDegree[empty] [1]<10 p=-10 else p=-15 ok
                             translate(10,p)
                       but nDegree = 180
                              if btnDegree[empty] [1]<10 p1= 30 p2=-10 else p1=35 p2=-10 ok
                              translate(p1,p2)
                       but nDegree = 270
                             if btnDegree[empty] [1]<10 p=10 else p=15 ok
                             translate(30,p)
                       but nDegree = -90
                             if btnDegree[empty] [1]<10 p=10 else p=15 ok
                             translate(30,p)
                       but nDegree = -180
                              if btnDegree[empty] [1]<10 p1=30 p2=-10 else p1=35 p2=-10 ok
                              translate(p1,p2)
                       but nDegree = -270
                             if btnDegree[empty] [1]<10 p1=10 p2=-10 else p1=10 p2=-15 ok
                             translate(p1,p2)
                       ok
                       rotate(nDegree)
	          drawtext(0,0,this.Text())
                       endpaint()
         }
         oLabel {
                    setpicture(picture)
                     show()
                    }
         return

Ruby

require 'io/console'

class Board
  SIZE = 4
  RANGE = 0...SIZE

  def initialize
    width = (SIZE*SIZE-1).to_s.size
    @frame = ("+" + "-"*(width+2)) * SIZE + "+"
    @form = "| %#{width}d " * SIZE + "|"
    @step = 0
    @orign = [*0...SIZE*SIZE].rotate.each_slice(SIZE).to_a.freeze
    @board = @orign.map{|row | row.dup}
    randomize
    draw
    message
    play
  end

  private

  def randomize
    @board[0][0], @board[SIZE-1][SIZE-1] = 0, 1
    @board[SIZE-1][0], @board[0][SIZE-1] = @board[0][SIZE-1], @board[SIZE-1][0]
    x, y, dx, dy = 0, 0, 1, 0
    50.times do
      nx,ny = [[x+dx,y+dy], [x+dy,y-dx], [x-dy,y+dx]]
                .select{|nx,ny| RANGE.include?(nx) and RANGE.include?(ny)}
                .sample
      @board[nx][ny], @board[x][y] = 0, @board[nx][ny]
      x, y, dx, dy = nx, ny, nx-x, ny-y
    end
    @x, @y = x, y
  end

  def draw
    puts "\e[H\e[2J"
    @board.each do |row|
      puts @frame
      puts (@form % row).sub(" 0 ", "   ")
    end
    puts @frame
    puts "Step: #{@step}"
  end

  DIR = {up: [-1,0], down: [1,0], left: [0,-1], right: [0,1]}
  def move(direction)
    dx, dy = DIR[direction]
    nx, ny = @x + dx, @y + dy
    if RANGE.include?(nx) and RANGE.include?(ny)
      @board[nx][ny], @board[@x][@y] = 0, @board[nx][ny]
      @x, @y = nx, ny
      @step += 1
      draw
    end
  end

  def play
    until @board == @orign
      case  key_in
      when "\e[A", "w" then move(:up)
      when "\e[B", "s" then move(:down)
      when "\e[C", "d" then move(:right)
      when "\e[D", "a" then move(:left)

      when "q","\u0003","\u0004"  then exit
      when "h"  then message
      end
    end

    puts "Congratulations, you have won!"
  end

  def key_in
    input = STDIN.getch
    if input == "\e"
      2.times {input << STDIN.getch}
    end
    input
  end

  def message
    puts <<~EOM
      Use the arrow-keys or WASD on your keyboard to push board in the given direction.
      PRESS q TO QUIT (or Ctrl-C or Ctrl-D)
    EOM
  end
end

Board.new

{{out}}


+----+----+----+----+
|  5 |  7 |  2 | 13 |
+----+----+----+----+
|  6 |    |  8 | 12 |
+----+----+----+----+
| 10 |  3 |  1 | 15 |
+----+----+----+----+
|  9 |  4 | 14 | 11 |
+----+----+----+----+
Step: 0
Use the arrow-keys or WASD on your keyboard to push board in the given direction.
PRESS q TO QUIT (or Ctrl-C or Ctrl-D)

Run BASIC

call SetCSS
' ---- fill 15 squares with 1 to 15
dim sq(16)
for i = 1 to 15: sq(i) = i: next

'----- shuffle the squares
[newGame]
for i = 1 to 100		' Shuffle the squares
	j	= rnd(0) * 16 + 1
	k	= rnd(0) * 16 + 1
	h	= sq(j)
	sq(j)	= sq(k)
	sq(k)	= h
next i

' ---- show the squares
[loop]
cls
html "<CENTER><TABLE><TR align=center>"
for i = 1 to 16
	html "<TD>"
	if sq(i) <> 0 then
		button	#pick, str$(sq(i)), [pick]
			#pick setkey(str$(i))
			#pick cssclass("lBtn")
	end if
	html "</TD>"
	if i mod 4 = 0 then html "</TR><TR align=center>"
next i
html "</table>"
wait

' ---- Find what square they picked
[pick]
picked	= val(EventKey$)
move	= 0             '                0000000001111111
if picked - 1 > 0 then  ' LEFT           1234567890123456
				if mid$(" *** *** *** ***",picked,1) = "*" and sq(picked -1) = 0 then move = -1 :end if
if picked + 1 < 17 then ' RIGHT
				if mid$("*** *** *** *** ",picked,1) = "*" and sq(picked +1) = 0 then move =  1 :end if
if picked - 4 > 0  then ' UP
				if mid$("    ************",picked,1) = "*" and sq(picked -4) = 0 then move = -4 :end if
if picked + 4 < 17 then ' DOWN
				if mid$("************    ",picked,1) = "*" and sq(picked +4) = 0 then move =  4 :end if
' ---- See if they picked a valid square next to the blank square
if move = 0 then
	print "Invalid move: ";sq(picked)
	wait
end if

' ---- Valid squire, switch it with the blank square
sq(picked + move) = sq(picked) ' move to the empty square
sq(picked) = 0
for i = 1 to 15  ' ---- If they got them all in a row they are a winner
	if sq(i) <> i then goto [loop]
next i

print "----- You are a winner -----"
input "Play again (Y/N)";a$
if a$ = "Y" then goto [newGame]		' set up new game
end

' ---- Make the squares look nice
SUB SetCSS
CSSClass ".lBtn", "{
background:wheat;border-width:5px;width:70px;
Text-Align:Center;Font-Size:24pt;Font-Weight:Bold;Font-Family:Arial;
}"
END SUB

Output: [[File:KokengeGame15.jpg]]

Rust

{{libheader|rand}}

extern crate rand;

use std::collections::HashMap;
use std::fmt;

use rand::Rng;
use rand::seq::SliceRandom;

#[derive(Copy, Clone, PartialEq, Debug)]
enum Cell {
    Card(usize),
    Empty,
}

#[derive(Eq, PartialEq, Hash, Debug)]
enum Direction {
    Up,
    Down,
    Left,
    Right,
}

enum Action {
    Move(Direction),
    Quit,
}

type Board = [Cell; 16];
const EMPTY: Board = [Cell::Empty; 16];

struct P15 {
    board: Board,
}

impl P15 {
    fn new() -> Self {
        let mut board = EMPTY;
        for (i, cell) in board.iter_mut().enumerate().skip(1) {
            *cell = Cell::Card(i);
        }

        let mut rng = rand::thread_rng();

        board.shuffle(&mut rng);
        if !Self::is_valid(board) {
            // random swap
            let i = rng.gen_range(0, 16);
            let mut j = rng.gen_range(0, 16);
            while j == i {
                j = rng.gen_range(0, 16);
            }
            board.swap(i, j);
        }

        Self { board }
    }

    fn is_valid(mut board: Board) -> bool {
        // TODO: optimize
        let mut permutations = 0;

        let pos = board.iter().position(|&cell| cell == Cell::Empty).unwrap();

        if pos != 15 {
            board.swap(pos, 15);
            permutations += 1;
        }

        for i in 1..16 {
            let pos = board
                .iter()
                .position(|&cell| match cell {
                    Cell::Card(value) if value == i => true,
                    _ => false,
                })
                .unwrap();

            if pos + 1 != i {
                board.swap(pos, i - 1);
                permutations += 1;
            }
        }

        permutations % 2 == 0
    }

    fn get_empty_position(&self) -> usize {
        self.board.iter().position(|&c| c == Cell::Empty).unwrap()
    }

    fn get_moves(&self) -> HashMap<Direction, Cell> {
        let mut moves = HashMap::new();
        let i = self.get_empty_position();

        if i > 3 {
            moves.insert(Direction::Up, self.board[i - 4]);
        }
        if i % 4 != 0 {
            moves.insert(Direction::Left, self.board[i - 1]);
        }
        if i < 12 {
            moves.insert(Direction::Down, self.board[i + 4]);
        }
        if i % 4 != 3 {
            moves.insert(Direction::Right, self.board[i + 1]);
        }
        moves
    }

    fn play(&mut self, direction: &Direction) {
        let i = self.get_empty_position();
        // This is safe because `ask_action` only returns legal moves
        match *direction {
            Direction::Up => self.board.swap(i, i - 4),
            Direction::Left => self.board.swap(i, i - 1),
            Direction::Right => self.board.swap(i, i + 1),
            Direction::Down => self.board.swap(i, i + 4),
        };
    }

    fn is_complete(&self) -> bool {
        self.board.iter().enumerate().all(|(i, &cell)| match cell {
            Cell::Card(value) => value == i + 1,
            Cell::Empty => i == 15,
        })
    }
}

impl fmt::Display for P15 {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        r#try!(write!(f, "+----+----+----+----+\n"));
        for (i, &cell) in self.board.iter().enumerate() {
            match cell {
                Cell::Card(value) => r#try!(write!(f, "| {:2} ", value)),
                Cell::Empty => r#try!(write!(f, "|    ")),
            }

            if i % 4 == 3 {
                r#try!(write!(f, "|\n"));
                r#try!(write!(f, "+----+----+----+----+\n"));
            }
        }
        Ok(())
    }
}

fn main() {
    let mut p15 = P15::new();

    for turns in 1.. {
        println!("{}", p15);
        match ask_action(&p15.get_moves()) {
            Action::Move(direction) => {
                p15.play(&direction);
            }
            Action::Quit => {
                println!("Bye !");
                break;
            }
        }

        if p15.is_complete() {
            println!("Well done ! You won in {} turns", turns);
            break;
        }
    }
}

fn ask_action(moves: &HashMap<Direction, Cell>) -> Action {
    use std::io::{self, Write};
    use Action::*;
    use Direction::*;

    println!("Possible moves:");

    if let Some(&Cell::Card(value)) = moves.get(&Up) {
        println!("\tU) {}", value);
    }
    if let Some(&Cell::Card(value)) = moves.get(&Left) {
        println!("\tL) {}", value);
    }
    if let Some(&Cell::Card(value)) = moves.get(&Right) {
        println!("\tR) {}", value);
    }
    if let Some(&Cell::Card(value)) = moves.get(&Down) {
        println!("\tD) {}", value);
    }
    println!("\tQ) Quit");
    print!("Choose your move : ");
    io::stdout().flush().unwrap();

    let mut action = String::new();
    io::stdin().read_line(&mut action).expect("read error");
    match action.to_uppercase().trim() {
        "U" if moves.contains_key(&Up) => Move(Up),
        "L" if moves.contains_key(&Left) => Move(Left),
        "R" if moves.contains_key(&Right) => Move(Right),
        "D" if moves.contains_key(&Down) => Move(Down),
        "Q" => Quit,
        _ => {
            println!("Unknown action: {}", action);
            ask_action(moves)
        }
    }
}

Scala

import java.util.Random

import jline.console._

import scala.annotation.tailrec
import scala.collection.immutable
import scala.collection.parallel.immutable.ParVector

object FifteenPuzzle {
  def main(args: Array[String]): Unit = play()

  @tailrec def play(len: Int = 1000): Unit = if(gameLoop(Board.randState(len))) play(len)
  def gameLoop(board: Board): Boolean = {
    val read = new ConsoleReader()
    val km = KeyMap.keyMaps().get("vi-insert")
    val opMap = immutable.HashMap[Operation, Char](
      Operation.PREVIOUS_HISTORY -> 'u',
      Operation.BACKWARD_CHAR -> 'l',
      Operation.NEXT_HISTORY -> 'd',
      Operation.FORWARD_CHAR -> 'r')

    @tailrec
    def gloop(b: Board): Boolean = {
      println(s"\u001B[2J\u001B[2;0H$b\n←↑→↓q")
      if(b.isSolved) println("Solved!\nPlay again? (y/n)")

      read.readBinding(km) match{
        case Operation.SELF_INSERT => read.getLastBinding match{
          case "q" => false
          case "y" if b.isSolved => true
          case "n" if b.isSolved => false
          case _ => gloop(b)
        }
        case op: Operation if opMap.isDefinedAt(op) => gloop(b.move(opMap(op)))
        case _ => gloop(b)
      }
    }

    gloop(board)
  }

  case class Board(mat: immutable.HashMap[(Int, Int), Int], x: Int, y: Int) {
    def move(mvs: Seq[Char]): Board = mvs.foldLeft(this){case (b, m) => b.move(m)}
    def move(mov: Char): Board = mov match {
      case 'r' if x < 3 => Board(mat ++ Seq(((x, y), mat((x + 1, y))), ((x + 1, y), 0)), x + 1, y)
      case 'l' if x > 0 => Board(mat ++ Seq(((x, y), mat((x - 1, y))), ((x - 1, y), 0)), x - 1, y)
      case 'd' if y < 3 => Board(mat ++ Seq(((x, y), mat((x, y + 1))), ((x, y + 1), 0)), x, y + 1)
      case 'u' if y > 0 => Board(mat ++ Seq(((x, y), mat((x, y - 1))), ((x, y - 1), 0)), x, y - 1)
      case _ => this
    }

    def isSolved: Boolean = sumDist == 0
    def sumDist: Int = mat.to(LazyList).map{ case ((a, b), n) => if(n == 0) 6 - a - b else (a + b - ((n - 1) % 4) - ((n - 1) / 4)).abs }.sum

    override def toString: String = {
      val lst = mat.toVector.map { case ((a, b), n) => (4 * b + a, n) }.sortWith(_._1 < _._1).map(_._2)
      lst.map { n => if (n == 0) "  " else f"$n%2d" }.grouped(4).map(_.mkString(" ")).mkString("\n")
    }
  }

  object Board {
    val moves: Vector[Char] = Vector('r', 'l', 'd', 'u')

    def apply(config: Vector[Int]): Board = {
      val ind = config.indexOf(0)
      val formed = config.zipWithIndex.map { case (n, i) => ((i % 4, i / 4), n) }
      val builder = immutable.HashMap.newBuilder[(Int, Int), Int]
      builder ++= formed
      Board(builder.result, ind % 4, ind / 4)
    }

    def solveState: Board = apply((1 to 15).toVector :+ 0)
    def randState(len: Int, rand: Random = new Random()): Board = Iterator
      .fill(len)(moves(rand.nextInt(4)))
      .foldLeft(Board.solveState) { case (state, mv) => state.move(mv) }
  }
}

Scheme


(import (scheme base)
        (scheme read)
        (scheme write)
        (srfi 27))    ; random numbers

(define *start-position* #(1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 #\space))
(random-source-randomize! default-random-source)

;; return a 16-place vector with the tiles randomly shuffled
(define (create-start-position)
  (let ((board (vector-copy *start-position*)))
    (do ((i 0 (+ 1 i))
         (moves (find-moves board) (find-moves board)))
      ((and (>= i 100)
            (not (finished? board)))
       board)
      (make-move board
                 (list-ref moves (random-integer (length moves)))))))

;; return index of space
(define (find-space board)
  (do ((i 0 (+ 1 i)))
    ((equal? #\space (vector-ref board i)) i)))

;; return a list of symbols indicating available moves
(define (find-moves board)
  (let* ((posn (find-space board))
         (row (quotient posn 4))
         (col (remainder posn 4))
         (result '()))
    (when (> row 0) (set! result (cons 'up result)))
    (when (< row 3) (set! result (cons 'down result)))
    (when (> col 0) (set! result (cons 'left result)))
    (when (< col 3) (set! result (cons 'right result)))
    result))

;; make given move - assume it is legal
(define (make-move board move)
  (define (swap posn-1 posn-2)
    (let ((tmp (vector-ref board posn-1)))
      (vector-set! board posn-1 (vector-ref board posn-2))
      (vector-set! board posn-2 tmp)))
  ;
  (let ((posn (find-space board)))
    (case move
      ((left)
       (swap posn (- posn 1)))
      ((right)
       (swap posn (+ posn 1)))
      ((up)
       (swap posn (- posn 4)))
      ((down)
       (swap posn (+ posn 4))))))

(define (finished? board)
  (equal? board *start-position*))

(define (display-board board)
  (do ((i 0 (+ 1 i)))
    ((= i (vector-length board)) (newline))
    (when (zero? (modulo i 4)) (newline))
    (let ((curr (vector-ref board i)))
      (display curr)
      (display (if (and (number? curr)
                        (> curr 9))
                 " "
                 "  ")))))

;; the main game loop
(define (play-game)
  (let ((board (create-start-position)))
    (do ((count 1 (+ count 1))
         (moves (find-moves board) (find-moves board)))
      ((finished? board)
       (display (string-append "\nCOMPLETED PUZZLE in "
                               (number->string count)
                               " moves\n")))
      (display-board board)
      (display "Enter a move: ") (display moves) (newline)
      (let ((move (read)))
        (if (memq move moves)
          (make-move board move)
          (display "Invalid move - try again"))))))

(play-game)

{{out}}


1  2     3
5  7  6  11
13 14 8  4
10 9  15 12
Enter a move: (right left down)
right

1  2  3
5  7  6  11
13 14 8  4
10 9  15 12
Enter a move: (left down)
down

1  2  3  11
5  7  6
13 14 8  4
10 9  15 12
Enter a move: (left down up)
down

1  2  3  11
5  7  6  4
13 14 8
10 9  15 12
Enter a move: (left down up)

Scilab

tiles=[1:15,0]; solution=[tiles(1:4);... tiles(5:8);... tiles(9:12);... tiles(13:16)]; solution=string(solution); solution(16)=" ";

init_pos=grand(1,"prm",tiles); puzzle=[init_pos(1:4);... init_pos(5:8);... init_pos(9:12);... init_pos(13:16)]; puzzle=string(puzzle);

blank_pos=[]; for i=1:4 for j=1:4 if puzzle(i,j)=="0" then blank_pos=[i,j]; end end end

clear i j

puzzle(blank_pos(1),blank_pos(2))=" ";

n_moves=0; solved=%F; while ~solved disp(puzzle); mprintf("\n");

neighbours=[0 -1;...
           -1  0;...
            0 +1;...
           +1  0];
neighbours(:,1)=neighbours(:,1)+blank_pos(1);
neighbours(:,2)=neighbours(:,2)+blank_pos(2);
neighbours=[neighbours zeros(4,1)]

i=0;
for i=1:4
    if ~(neighbours(i,1)<1 | neighbours(i,1)>4 |...
       neighbours(i,2)<1 | neighbours(i,2)>4) then
       neighbours(i,3)=evstr(puzzle(neighbours(i,1),neighbours(i,2)));
   end
end

valid_move=%F;
while ~valid_move
    move_tile=[];
    move_tile=input("Enter tile you want to move (0 to exit):");
    if sum(move_tile==neighbours(:,3)) & move_tile~=0 then
        valid_move=%T;
        n_moves=n_moves+1;
    elseif move_tile==0 then
        disp("Exit");
        abort
    else
        disp(puzzle);
        disp("Invalid input");
    end
end

neighb_i=find(neighbours(:,3)'==move_tile);
puzzle(neighbours(neighb_i,1),neighbours(neighb_i,2))=" ";
puzzle(blank_pos(1),blank_pos(2))=string(move_tile);
blank_pos=neighbours(neighb_i,1:2);

if sum(puzzle==solution)==16 then
    solved=%T;
    disp(puzzle);
    mprintf("\n"+...
            "   _____       _               _ _ \n"+...
            "  / ____|     | |             | | |\n"+...
            " | (___   ___ | |_   _____  __| | |\n"+...
            "  \\___ \\ / _ \\| \\ \\ / / _ \\/ _` | |\n"+...
            "  ____) | (_) | |\\ V /  __/ (_| |_|\n"+...
            " |_____/ \\___/|_| \\_/ \\___|\\__,_(_)\n")
end

end

disp("Solved in "+string(n_moves)+" moves.");



{{out}}

This test was run while making <code>init_pos=[1 2 3 4 5 6 7 8 9 14 10 11 13 0 15 12]</code>.


```txt
!1   2   3   4   !
!                !
!5   6   7   8   !
!                !
!9   14  10  11  !
!                !
!13      15  12  !

Enter tile you want to move (0 to exit):
14

!1   2   3   4   !
!                !
!5   6   7   8   !
!                !
!9       10  11  !
!                !
!13  14  15  12  !

Enter tile you want to move (0 to exit):
10


!1   2   3   4   !
!                !
!5   6   7   8   !
!                !
!9   10      11  !
!                !
!13  14  15  12  !

Enter tile you want to move (0 to exit):
11


!1   2   3   4   !
!                !
!5   6   7   8   !
!                !
!9   10  11      !
!                !
!13  14  15  12  !

Enter tile you want to move (0 to exit):
12


!1   2   3   4   !
!                !
!5   6   7   8   !
!                !
!9   10  11  12  !
!                !
!13  14  15      !

   _____       _               _ _
  / ____|     | |             | | |
 | (___   ___ | |_   _____  __| | |
  \___ \ / _ \| \ \ / / _ \/ _` | |
  ____) | (_) | |\ V /  __/ (_| |_|
 |_____/ \___/|_| \_/ \___|\__,_(_)

 Solved in 4 moves.

Simula


BEGIN
    CLASS FIFTEENPUZZLE(NUMTILES, SIDE, WIDTH, SEED);
        INTEGER NUMTILES, SIDE, WIDTH, SEED;
    BEGIN
        INTEGER ARRAY TILES(0:NUMTILES);
        INTEGER BLANKPOS;

        PROCEDURE INVARIANT;
        BEGIN
            INTEGER ARRAY UQ(0:NUMTILES);
            INTEGER I;
            FOR I := 0 STEP 1 UNTIL NUMTILES DO UQ(I) := -1;
            FOR I := 0 STEP 1 UNTIL NUMTILES DO
            BEGIN
                INTEGER T;
                T := TILES(I);
                IF UQ(T) <> -1 THEN ERROR("TILES ARE NOT UNIQUE");
                UQ(T) := T;
            END;
            IF TILES(BLANKPOS) <> 0 THEN ERROR("BLANKPOS IS NOT BLANK");
        END;

        PROCEDURE SHUFFLE;
        BEGIN
            BOOLEAN B;
            WHILE NOT B DO
            BEGIN
                INTEGER N;
                RESET;
                ! DON'T INCLUDE THE BLANK SPACE IN THE SHUFFLE, LEAVE IT
                ! IN THE HOME POSITION ;
                N := NUMTILES;
                WHILE N > 1 DO
                BEGIN
                    INTEGER R, TMP;
                    R := UNIFORM(0, N, SEED); N := N - 1;
                    TMP := TILES(R);
                    TILES(R) := TILES(N);
                    TILES(N) := TMP;
                END;
                B := ISSOLVABLE;
            END;
            INVARIANT;
        END;

        PROCEDURE RESET;
        BEGIN
            INTEGER I;
            FOR I := 0 STEP 1 UNTIL NUMTILES DO
                TILES(I) := MOD((I + 1), NUMTILES + 1);
            BLANKPOS := NUMTILES;
            INVARIANT;
        END;

        ! ONLY HALF THE PERMUTATIONS OF THE PUZZLE ARE SOLVABLE.
        ! WHENEVER A TILE IS PRECEDED BY A TILE WITH HIGHER VALUE IT COUNTS
        ! AS AN INVERSION. IN OUR CASE, WITH THE BLANK SPACE IN THE HOME
        ! POSITION, THE NUMBER OF INVERSIONS MUST BE EVEN FOR THE PUZZLE
        ! TO BE SOLVABLE.
        ! SEE ALSO:
        ! WWW.CS.BHAM.AC.UK/~MDR/TEACHING/MODULES04/JAVA2/TILESSOLVABILITY.HTML
        ;

        BOOLEAN PROCEDURE ISSOLVABLE;
        BEGIN
            INTEGER COUNTINVERSIONS;
            INTEGER I, J;
            FOR I := 0 STEP 1 UNTIL NUMTILES - 1 DO
                FOR J := 0 STEP 1 UNTIL I - 1 DO
                    IF TILES(J) > TILES(I) THEN
                        COUNTINVERSIONS := COUNTINVERSIONS + 1;
            ISSOLVABLE := MOD(COUNTINVERSIONS, 2) = 0;
        END;

        PROCEDURE PRINTBOARD;
        BEGIN
            INTEGER I, J;

            PROCEDURE PRINTLINE;
            BEGIN
              INTEGER ROW, COL;
              !      +-----+-----+-----+-----+ ;
              FOR ROW := 1 STEP 1 UNTIL SIDE DO
              BEGIN
                  OUTCHAR('+');
                  FOR COL := 0 STEP 1 UNTIL WIDTH DO OUTCHAR('-');
              END;
              OUTCHAR('+');
              OUTIMAGE;
            END;

            PROCEDURE PRINTCELL(T); INTEGER T;
            BEGIN
                IF T = 0 THEN
                BEGIN
                    INTEGER R;
                    FOR R := 1 STEP 1 UNTIL WIDTH DO
                        OUTCHAR(' ');
                END
                ELSE OUTINT(T, WIDTH);
                OUTCHAR(' ');
            END;

            !      +-----+-----+-----+-----+
            !      |  1  |  2  |  3  |  4  |
            !      +-----+-----+-----+-----+
            !      |  5  |  6  |  7  |  8  |
            !      +-----+-----+-----+-----+
            !      |  9  |  10 |  11 |     |
            !      +-----+-----+-----+-----+
            !      |  13 |  14 |  15 |  12 |
            !      +-----+-----+-----+-----+   ;

            FOR I := 1 STEP 1 UNTIL SIDE DO
            BEGIN
                PRINTLINE;
                OUTCHAR('|');
                FOR J := 1 STEP 1 UNTIL SIDE DO
                BEGIN
                    INTEGER T;
                    T := TILES((I - 1) * SIDE + (J - 1));
                    PRINTCELL(T);
                    OUTCHAR('|');
                END;
                OUTIMAGE;
            END;
            PRINTLINE;
        END;

        BOOLEAN PROCEDURE DONE;
        BEGIN
            BOOLEAN ORDERED;
            INTEGER I, EXPECT;
            ORDERED := TRUE;
            EXPECT := 1;
            FOR I := 0 STEP 1 UNTIL NUMTILES - 1 DO
            BEGIN
                IF I <> BLANKPOS THEN
                BEGIN
                    IF TILES(I) <> EXPECT THEN
                        ORDERED := FALSE;
                    EXPECT := EXPECT + 1;
                END;
            END;
            DONE := ORDERED;
        END;

        PROCEDURE REQUEST;
        BEGIN
            INTEGER ARRAY CANDIDATES(1:4);
            INTEGER I, CANDCOUNT, CHOOSE;
            BOOLEAN VALIDINPUT;

            PROCEDURE ADDCAND(IDX); INTEGER IDX;
            BEGIN
                IF IDX >= 0 AND IDX <= NUMTILES THEN
                BEGIN
                    CANDCOUNT := CANDCOUNT + 1;
                    CANDIDATES(CANDCOUNT) := TILES(IDX);
                END;
            END;

            PRINTBOARD;

            IF BLANKPOS <= NUMTILES - SIDE     THEN ADDCAND(BLANKPOS + SIDE);
            IF BLANKPOS >= SIDE                THEN ADDCAND(BLANKPOS - SIDE);
            IF MOD(BLANKPOS, SIDE) <> SIDE - 1 THEN ADDCAND(BLANKPOS + 1);
            IF MOD(BLANKPOS, SIDE) <> 0        THEN ADDCAND(BLANKPOS - 1);

            WHILE NOT VALIDINPUT DO
            BEGIN
                OUTTEXT("YOUR MOVE: ");

                FOR I := 1 STEP 1 UNTIL CANDCOUNT DO
                    OUTINT(CANDIDATES(I), SIDE);
                OUTIMAGE;
                CHOOSE := ININT;

                FOR I := 1 STEP 1 UNTIL CANDCOUNT DO
                    IF CHOOSE = CANDIDATES(I) THEN
                    BEGIN
                        INTEGER LOOKUP;
                        FOR LOOKUP := 0 STEP 1 UNTIL NUMTILES DO
                            IF NOT VALIDINPUT AND TILES(LOOKUP) = CHOOSE THEN
                            BEGIN
                                TILES(BLANKPOS) := TILES(LOOKUP);
                                TILES(LOOKUP) := 0;
                                BLANKPOS := LOOKUP;
                                INVARIANT;
                                VALIDINPUT := TRUE;
                            END;
                    END;

                IF NOT VALIDINPUT THEN
                BEGIN
                    OUTTEXT("INVALID INPUT!");
                    OUTIMAGE;
                END;
            END;
        END;

        SHUFFLE;
    END;

    REF(FIFTEENPUZZLE) P;

    OUTTEXT("INPUT RANDOM SEED: ");
    OUTIMAGE;
    P :- NEW FIFTEENPUZZLE(15, 4, 3, ININT); ! ININT = RANDOM SEED ;
    WHILE NOT P.DONE DO
        P.REQUEST;
    P.PRINTBOARD;
END.

{{out}}

INPUT RANDOM SEED:
456
+----+----+----+----+
| 15 |  8 | 13 | 14 |
+----+----+----+----+
|  1 |  2 |  9 |  4 |
+----+----+----+----+
| 12 |  3 |  5 |  7 |
+----+----+----+----+
| 11 |  6 | 10 |    |
+----+----+----+----+
YOUR MOVE:    7  10
7
+----+----+----+----+
| 15 |  8 | 13 | 14 |
+----+----+----+----+
|  1 |  2 |  9 |  4 |
+----+----+----+----+
| 12 |  3 |  5 |    |
+----+----+----+----+
| 11 |  6 | 10 |  7 |
+----+----+----+----+
YOUR MOVE:    7   4   5
4
+----+----+----+----+
| 15 |  8 | 13 | 14 |
+----+----+----+----+
|  1 |  2 |  9 |    |
+----+----+----+----+
| 12 |  3 |  5 |  4 |
+----+----+----+----+
| 11 |  6 | 10 |  7 |
+----+----+----+----+
YOUR MOVE:    4  14   9
...

Standard ML

{{works with|SML/NJ}} {{works with|Moscow ML}}


(* Load required Modules for Moscow ML *)
load "Int";
load "Random";


(* Mutable Matrix *)
signature MATRIX =
sig
	type 'a matrix
	val construct : 'a -> int * int -> 'a matrix
	val size : 'a matrix -> int * int
	val get : 'a matrix -> int * int -> 'a
	val set : 'a matrix -> int * int -> 'a -> unit
end

structure Matrix :> MATRIX =
struct
	(* Array of rows, where the rows are a array of 'a *)
	type 'a matrix = 'a Array.array Array.array

	fun 'a construct (a : 'a) (width, height) : 'a matrix =
		if width < 1 orelse height < 1
			then raise Subscript
			else Array.tabulate (height, fn _ => Array.tabulate (width, fn _ => a))

	fun size b =
		let
			val firstrow = Array.sub (b, 0)
		in
			(Array.length firstrow, Array.length b)
		end


	fun get b (x, y) = Array.sub (Array.sub (b, y), x)

	fun set b (x, y) v = Array.update (Array.sub (b, y), x, v)
end

signature P15BOARD =
sig
	type board
	datatype direction = North | East | South | West

	val construct : int * int -> board
	val emptyField : board -> int * int
	val get : board -> int * int -> int option
	val size : board -> int * int

	exception IllegalMove
	val moves : board -> int list
	val move : board -> int -> unit

	val issolved : board -> bool
end

(* Game Logic and data *)

structure Board :> P15BOARD =
struct
	(* Matrix + empty Field position *)
	type board = int option Matrix.matrix * (int * int) ref

	datatype direction = North | East | South | West

	exception IllegalMove

	fun numberat width (x, y) = (y*width + x + 1)

	fun construct (width, height) =
		let
			val emptyBoard : int option Matrix.matrix = Matrix.construct NONE (width, height)
		in
			(* Fill the board with numbers *)
			List.tabulate (height, fn y => List.tabulate (width, fn x =>
					Matrix.set emptyBoard (x, y) (SOME (numberat width (x, y)))));
			(* Clear the last field *)
			Matrix.set emptyBoard (width-1, height-1) NONE;
			(* Return the board *)
			(emptyBoard, ref (width-1, height-1))
		end

	fun emptyField (_, rfield) = !rfield

	fun get (mat, _) (x, y) = Matrix.get mat (x, y)

	fun size (mat, _) = Matrix.size mat

	(* toggle the empty field with a given field *)
	fun toggle (mat, rpos) pos =
		let
			val pos' = !rpos
			val value = Matrix.get mat pos
		in
			Matrix.set mat pos NONE;
			Matrix.set mat pos' value;
			rpos := pos
		end

	(* Get list of positions of the neighbors of a given field *)
	fun neighbors mat (x, y) : (int * int) list =
		let
			val (width, height) = Matrix.size mat
			val directions = [(x, y-1), (x+1, y), (x, y+1), (x-1, y)]
		in
			List.mapPartial (fn pos => SOME (Matrix.get mat pos; pos) handle Subscript => NONE) directions
		end

	fun moves (mat, rpos) =
		let
			val neighbors = neighbors mat (!rpos)
		in
			map (fn pos => valOf (Matrix.get mat pos)) neighbors
		end

	fun move (mat, rpos) m =
		let
			val (hx, hy) = !rpos
			val neighbors = neighbors mat (hx, hy)
			val optNeighbor = List.find (fn pos => SOME m = Matrix.get mat pos) neighbors
		in
			if isSome optNeighbor
			then
				toggle (mat, rpos) (valOf optNeighbor)
			else
				raise IllegalMove
		end

	fun issolved board =
		let
			val (width, height) = size board
			val xs = List.tabulate (width,  fn x => x)
			val ys = List.tabulate (height, fn y => y)
		in
			List.all (fn x => List.all (fn y => (x + 1 = width andalso y + 1 = height) orelse get board (x, y) = SOME (numberat width (x,y))) ys) xs
		end
end

(* Board Shuffle *)
signature BOARDSHUFFLE =
sig
	val shuffle : Board.board -> int -> unit
end

structure Shuffle :> BOARDSHUFFLE =
struct
	(*
	 * Note: Random Number Interfaces are different in SML/NJ and Moscow ML. Comment out the corresponding version:
	 *)

	(*
	(* SML/NJ - Version *)
	val time = Time.now ()
	val timeInf = Time.toMicroseconds time
	val timens = Int.fromLarge (LargeInt.mod (timeInf, 1073741823));
	val rand = Random.rand (timens, timens)

	fun next n = Random.randRange (0, n) rand
	*)

	(* Moscow ML - Version *)
	val generator = Random.newgen ()
	fun next n = Random.range (0, n) generator


	fun shuffle board 0 = if (Board.issolved board) then shuffle board 1 else ()
	  | shuffle board n =
	  	let
			val moves = Board.moves board
			val move  = List.nth (moves, next (List.length moves - 1))
		in
			Board.move board move;
			shuffle board (n-1)
		end
end


(* Console interface *)

signature CONSOLEINTERFACE =
sig
	val start : unit -> unit
	val printBoard : Board.board -> unit
end

structure Console :> CONSOLEINTERFACE =
struct
	fun cls () = print "\^[[1;1H\^[[2J"

	fun promptNumber prompt =
		let
			val () = print prompt
			(* Input + "\n" *)
			val line   = valOf (TextIO.inputLine TextIO.stdIn)
			val length = String.size line
			val input  = String.substring (line, 0, length - 1)
			val optnum = Int.fromString input
		in
			if isSome optnum
				then valOf optnum
				else (print "Input is not a number.\n"; promptNumber prompt)
		end

	fun fieldToString (SOME x) = Int.toString x
	  | fieldToString (NONE  ) = ""

	fun boardToString board =
		let
			val (width, height) = Board.size board
			val xs = List.tabulate (width,  fn x => x)
			val ys = List.tabulate (height, fn y => y)
		in
			foldl (fn (y, str) => (foldl (fn (x, str') => str' ^ (fieldToString (Board.get board (x, y))) ^ "\t") str xs) ^ "\n") "" ys
		end

	fun printBoard board = print (boardToString board)


	fun loop board =
		let
			val rvalidInput = ref false
			val rinput      = ref 42
			val () = cls ()
			val () = printBoard board
		in
			(* Ask for a move and repeat until it is a valid move *)
			while (not (!rvalidInput)) do
				(
					rinput := promptNumber "Input the number to move: ";
					Board.move board (!rinput);
					rvalidInput := true
				) handle Board.IllegalMove => print "Illegal move!\n"
		end


	fun start () =
		let
			val () = cls ()
			val () = print "Welcome to nxm-Puzzle!\n"
			val (width, height) = (promptNumber "Enter the width: ", promptNumber "Enter the height: ")
			val diff = (promptNumber "Enter the difficulty (number of shuffles): ")
			val board = Board.construct (width, height)
		in
			Shuffle.shuffle board diff;
			while (not (Board.issolved board)) do loop board;
			print "Solved!\n"
		end
end


val () = Console.start()

Note: The interface for generating random numbers is different in SML/NJ and Moscow ML. Comment out the corresponding parts of code.

The dimensions of the board (eg. 4x4) and the number of shuffles should be entered first.

Tcl

{{libheader|Tk}} Works with Tcl/Tk 8.5

This program uses Tk, the graphical counterpart to Tcl. The tiles are made of a grid of buttons, and the text on the buttons is moved around.

The button "New game" selects one of the canned puzzles. The window-title is used to show messages.

 # 15puzzle_21.tcl - HaJo Gurt -  2016-02-16
 # http://wiki.tcl.tk/14403

 #: 15-Puzzle - with grid, buttons and colors

  package require Tk

  set progVersion "15-Puzzle v0.21";        # 2016-02-20

  global Msg Moves PuzzNr GoalNr
  set Msg    " "
  set Moves  -1
  set PuzzNr  0
  set GoalNr  0

  set Keys   { 11 12 13 14  21 22 23 24  31 32 33 34  41 42 43 44 }

  set Puzz_T {  T  h  e  F   i  f  t  e   e  n  P  u   z  z  l  e }; # Title
  set Goal_T {  x  x  x  F   i  f  t  e   e  n  x  x   x  x  x  x }; # Title-highlight

  set Puzz_0 {  E  G  P  N   C  A  F  B   D  L  H  I   O  K  M  _ }; # -  / 116
  set Puzz_1 {  C  A  F  B   E  G  P  N   D  L  H  I   O  K  M  _ }; # E  / 156 from Tk-demo
  set Puzz_2 {  E  O  N  K   M  I  _  G   B  H  L  P   C  F  A  D }; # L  / 139
  set Puzz_3 {  P  G  M  _   E  L  N  D   O  K  H  I   B  C  F  A }; # EK / 146

  set Goal_0 {  A  B  C  D   E  F  G  H   I  K  L  M   N  O  P  _ }; # Rows LTR   / 1:E : 108
  set Goal_1 {  A  E  I  N   B  F  K  O   C  G  L  P   D  H  M  _ }; # Cols forw. / 1:M : 114

  set Puzz $Puzz_T
  set Goal $Goal_T

#---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+---

  proc Move {k} {
  # find the key with the empty tile:
    set e -1
    foreach p $::Keys  {
      set t [.key$p cget -text]
      if { $t eq "_" } { set e $p }
    }
    if {$e  <  0} {return 0};   # no key with empty tile found
    if {$k == $e} {return 0};   # click was on the empty tile

    set t [.key$k cget -text]
    .key$e config -text $t
    .key$k config -text "_";
    return 1
  }

  proc Check {} {
    set ok 0
    set i  0
    foreach k $::Keys {
      set t [.key$k cget -text]
      set g [lindex $::Goal $i]
      incr i

      .key$k config -background white
      if { $t eq $g  } { .key$k config -background lightgreen; incr ok }
      if { $t eq "_" } { .key$k config -background gray }
    }

    # Solved:
    update
    if { $ok > 15 && $::Moves > 0} {
      foreach k $::Keys  {
        .key$k flash; bell;
      }
    }
  }

  proc Click {k} {
    set ::Msg ""
    set val [.key$k cget -text]
    set ok [Move $k]

    incr ::Moves $ok
    wm title . "$::Moves moves"
    Check
  }

  proc ShowKeys {} {
    set i 0
    foreach k $::Keys  {
      set t [lindex $::Puzz $i]
      incr i
      .key$k config -text $t -background white;
    }
    Check
  }

  proc NewGame {N} {
    global Msg Moves PuzzNr GoalNr

    incr  PuzzNr $N
    if { $PuzzNr > 3} { set PuzzNr 0 }

                         set ::Goal $::Goal_0;
    if { $GoalNr == 1} { set ::Goal $::Goal_1; }

    if { $PuzzNr == 0} { set ::Puzz $::Puzz_0; }
    if { $PuzzNr == 1} { set ::Puzz $::Puzz_1; }
    if { $PuzzNr == 2} { set ::Puzz $::Puzz_2; }
    if { $PuzzNr == 3} { set ::Puzz $::Puzz_3; }

                  set Msg "Try again"
    if { $N>0 } { set Msg "New game" }

    set Moves 0
    ShowKeys
    wm title . "$Msg "
  }

#---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+---

  button .reset   -text "Restart"  -fg blue -command {NewGame  0}
  button .newGame -text "New Game" -fg red  -command {NewGame +1}

  foreach k $::Keys {
    button .key$k -text "$k" -width 4 -command "Click $k"
  }

  grid .newGame x .reset x -sticky nsew

  grid .key11 .key12 .key13 .key14  -sticky nsew  -padx 2 -pady 2
  grid .key21 .key22 .key23 .key24  -sticky nsew  -padx 2 -pady 2
  grid .key31 .key32 .key33 .key34  -sticky nsew  -padx 2 -pady 2
  grid .key41 .key42 .key43 .key44  -sticky nsew  -padx 2 -pady 2

  grid configure .newGame .reset  -columnspan 2 -padx 4

  ShowKeys; Check
  wm title . $progVersion
  focus -force .
  wm resizable . 0 0

# For some more versions, see:  http://wiki.tcl.tk/15067 : Classic 15 Puzzle and http://wiki.tcl.tk/15085 : N-Puzzle

Wolfram Language


grid = MapThread[{#1,#2} &, {Range @ 16, Range @ 16}]

Move[x_] := (empty = Select[grid, #[[1]]==16 &][[1,2]];
             If[(empty == x+4) || (empty == x-4) ||
                (Mod[empty,4] != 0 && empty == x-1) ||
                (Mod[empty,4] != 1 && empty == x+1),
             oldEmpty = grid[[empty]][[1]];
             grid[[empty]][[1]] = grid[[x]][[1]];
             grid[[x]][[1]] = oldEmpty])

CButton[{x_,loc_}] := If[x==16, Null, Button[x,Move @ loc]]

Dynamic @ Grid @ Partition[CButton /@ grid,4]

Visual Basic .NET

Public Class Board
    Inherits System.Windows.Forms.Form

    Const XbyX = 4
    Const XSize = 60

    Private Empty As New Panel
    Private Tiles As New List(Of Tile)
    Private Moves As Integer

    Public Sub New()
        Me.Text = XbyX ^ 2 - 1 & " Puzzle Game"
        Me.ClientSize = New Size(XbyX * XSize, XbyX * XSize)
        Me.FormBorderStyle = FormBorderStyle.FixedToolWindow
        Restart()
    End Sub

    Public Sub Restart()
        Dim Start As List(Of Integer) = MakeCompleteable(GetRandamStartOrder())

        Empty.SetBounds(((XbyX ^ 2 - 1) Mod XbyX) * XSize, ((XbyX ^ 2 - 1) \ XbyX) * XSize, XSize, XSize)

        Me.Moves = 0
        Me.Tiles.Clear()
        Me.Controls.Clear()
        For No = 0 To XbyX ^ 2 - 2
            Dim Tile As New Tile
            Tile.Text = Start(No)
            Tile.Board = Me
            Tile.SetBounds((No Mod XbyX) * XSize, (No \ XbyX) * XSize, XSize, XSize)
            Me.Tiles.Add(Tile)
            Me.Controls.Add(Tile)
        Next

    End Sub

    Public Sub IsComplete()
        Me.Moves += 1
        If Empty.Left = ((XbyX ^ 2 - 1) Mod XbyX) * XSize AndAlso Empty.Top = ((XbyX ^ 2 - 1) \ XbyX) * XSize Then
            Me.Tiles.Sort()
            For x = 1 To XbyX ^ 2 - 1
                If Not Tiles(x - 1).Text = x Then
                    Exit Sub
                End If
            Next
            MsgBox($"Completed in {Me.Moves} Moves!", MsgBoxStyle.Information, "Winner")
            Restart()
        End If
    End Sub

    Public Class Tile
        Inherits Button
        Implements IComparable(Of Tile)
        Public Board As Board
        Private Sub Tile_Click(sender As Object, e As EventArgs) Handles Me.Click
            With Board.Empty
                If Me.Left = .Left AndAlso (Me.Top + Me.Height = .Top OrElse .Top + .Height = Me.Top) Then
                    Swap()
                ElseIf Me.Top = .Top AndAlso (Me.Left + Me.Width = .Left OrElse .Left + .Width = Me.Left) Then
                    Swap()
                End If
            End With
        End Sub
        Private Sub Swap()
            Dim p = Board.Empty.Location
            Board.Empty.Location = Me.Location
            Me.Location = p
            Board.IsComplete()
        End Sub
        Public Function CompareTo(other As Tile) As Integer Implements IComparable(Of Tile).CompareTo
            Dim Result = Me.Top.CompareTo(other.Top)
            If Result = 0 Then
                Return Me.Left.CompareTo(other.Left)
            End If
            Return Result
        End Function
    End Class

    Public Function GetRandamStartOrder() As List(Of Integer)
        Dim List As New List(Of Integer)
        Dim Random As New Random()
        Do While List.Count < XbyX ^ 2 - 1
            Dim Value As Integer = Random.Next(1, XbyX ^ 2)
            If Not List.Contains(Value) Then
                List.Add(Value)
            End If
        Loop
        Return List
    End Function

    Public Function MakeCompleteable(List As List(Of Integer)) As List(Of Integer)
        'ToDo
        Return List
    End Function

End Class

VBA

This allows the user to specify the size of the grid (N x N). Only solvable layouts are displayed.

This uses InputBoxes to display the grid of tiles, and prompts the user to enter the number on the tile they wish to move into the empty space.

The last move is displayed on the input box, or an error message if an invalid move is attempted. When the puzzle is solved, the move count is displayed.


Public iSide As Integer
Public iSize As Integer
Public iGrid() As Integer
Public lMoves As Long
Public sMessage As String
Public Const sTitle As String = "Tile Puzzle"


Sub PlayGame()
    Dim iNum As Integer
    Dim i As Integer
    Dim vInput As Variant

DefineGrid:
    vInput = InputBox("Enter size of grid, as a whole number" & String(2, vbCr) & "(e.g. for a 4 x 4 grid, enter '4')", sTitle, 4)
    If vInput = "" Then Exit Sub
    If Not IsNumeric(vInput) Then GoTo DefineGrid
    iSide = vInput
    If iSide < 3 Or iNum > 10 Then GoTo DefineGrid
    iSize = iSide ^ 2
    ReDim iGrid(1 To iSize)

Initalize:
    InitializeGrid
    If Not IsSolvable Then GoTo Initalize

GetInput:
    vInput = InputBox(ShowGrid & vbCr & "Enter number to move into empty tile", sTitle)
    If vInput = "" Then
        If MsgBox("Are you sure? This will end the current game.", vbExclamation + vbYesNo, sTitle) = vbYes Then Exit Sub
    End If
    If Not IsNumeric(vInput) Then
        sMessage = "'" & vInput & "' is not a valid tile"
        GoTo GetInput
    End If
    iNum = vInput
    If iNum < 1 Or iNum > iSize - 1 Then
        sMessage = iNum & " is not a valid tile"
        GoTo GetInput
    End If
    i = FindTile(iNum)
    If Not ValidMove(i) Then GoTo GetInput
    MoveTile (i)
    If TestGrid Then
        MsgBox "SUCCESS! You solved the puzzle in " & lMoves & " moves", vbInformation + vbOKOnly, sTitle
    Else
        GoTo GetInput
    End If
End Sub

Function RandomTile() As Integer
    Randomize
    RandomTile = Int(Rnd * iSize) + 1
End Function

Function GetX(ByVal i As Integer) As Integer
    GetX = Int((i - 1) / iSide) + 1
End Function

Function GetY(ByVal i As Integer) As Integer
    GetY = (i - 1) Mod iSide + 1
End Function

Function GetI(ByVal x As Integer, y As Integer)
    GetI = (x - 1) * iSide + y
End Function

Function InitializeGrid()
    Dim i As Integer
    Dim x As Integer
    Dim y As Integer

    sMessage = "New " & iSide & " x " & iSide & " game started" & vbCr

    For i = 1 To iSize
        iGrid(i) = 0
    Next i
    For i = 1 To iSize - 1
        Do
            x = RandomTile
            If iGrid(x) = 0 Then iGrid(x) = i
        Loop Until iGrid(x) = i
    Next i
    lMoves = 0
End Function

Function IsSolvable() As Boolean
    Dim i As Integer
    Dim j As Integer
    Dim iCount As Integer
    For i = 1 To iSize - 1
        For j = i + 1 To iSize
            If iGrid(j) < iGrid(i) And iGrid(j) > 0 Then iCount = iCount + 1
        Next j
    Next i
    If iSide Mod 2 Then
        IsSolvable = Not iCount Mod 2
    Else
        IsSolvable = iCount Mod 2 = GetX(FindTile(0)) Mod 2
    End If
End Function

Function TestGrid() As Boolean
    Dim i As Integer

    For i = 1 To iSize - 1
        If Not iGrid(i) = i Then
            TestGrid = False
            Exit Function
        End If
    Next i
    TestGrid = True
End Function

Function FindTile(ByVal iNum As Integer) As Integer
    Dim i As Integer
    For i = 1 To iSize
        If iGrid(i) = iNum Then
            FindTile = i
            Exit Function
        End If
    Next i
End Function

Function ValidMove(ByVal i As Integer) As Boolean
    Dim e As Integer
    Dim xDiff As Integer
    Dim yDiff As Integer

    e = FindTile(0)
    xDiff = GetX(i) - GetX(e)
    yDiff = GetY(i) - GetY(e)
    If xDiff = 0 Then
        If yDiff = 1 Then
            sMessage = "Tile " & iGrid(i) & " was moved left"
            ValidMove = True
        ElseIf yDiff = -1 Then
            sMessage = "Tile " & iGrid(i) & " was moved right"
            ValidMove = True
        End If
    ElseIf yDiff = 0 Then
        If xDiff = 1 Then
            sMessage = "Tile " & iGrid(i) & " was moved up"
            ValidMove = True
        ElseIf xDiff = -1 Then
            sMessage = "Tile " & iGrid(i) & " was moved down"
            ValidMove = True
        End If
    End If
    If Not ValidMove Then sMessage = "Tile " & iGrid(i) & " may not be moved"
End Function

Function MoveTile(ByVal i As Integer)
    Dim e As Integer
    e = FindTile(0)
    iGrid(e) = iGrid(i)
    iGrid(i) = 0
    lMoves = lMoves + 1
End Function

Function ShowGrid()
    Dim x As Integer
    Dim y As Integer
    Dim i As Integer
    Dim sNum As String
    Dim s As String

    For x = 1 To iSide
        For y = 1 To iSide
            sNum = iGrid(GetI(x, y))
            If sNum = "0" Then sNum = ""
            s = s & sNum & vbTab
        Next y
        s = s & vbCr
    Next x
    If Not sMessage = "" Then
        s = s & vbCr & sMessage & vbCr
    End If
    ShowGrid = s
End Function

Sample output:


10  4   3   14
9   15  1   6
12  11  7   8
2   5       13

New 4 x 4 game started

Enter number to move into empty tile

=={{header|X86_64 Assembly}}==

        ; Puzzle15 by grosged (march 2019)
        ; How to play ?.. Just press one of the arrow keys then [enter] to valid
        ; ( press [Ctrl+C] to escape )

        segment	.data
check:	db	"1   2   3   4",10,"  5   6   7   8",10,"  9  10  11  12",10," 13  14  1"
puzzle:	db	27,"c",10,"  1   2   3   4",10,"  5   6   7   8",10,"  9  10  11  12",10," 13  14  15    ",10,10
	db	" Direction ?",13
	db	" Well done !  ",10,10
inKey:	dw	0,0,0,0

	segment	.text
	global	_start

_start:	mov	rax,100
	syscall
	mov	rcx,rax
	shr	rcx,3
	and	rcx,255
	and	rax,31
	lea	rsi,[_start+rax]
	mov	rbx,15

Mixing:	push	rcx
	mov	di,word[rsi+rcx*2]
	mov	rcx,8
quatre:	mov	ax,di
	shr	di,2
	and	ax,3
	add	ax,65
	call	SWAPPIN
	loop	quatre
	pop	rcx
	loop	Mixing
	cmp	cx,ax

MainLp:	mov	rdx,80
Succes:	lea	rsi,[puzzle]
	mov	rdi,1
	mov	rax,1
End?:	syscall
	mov	rax,60
	je	End?
	mov	rdx,8
	lea	rsi,[inKey]
	mov	rdi,0
	mov	rax,0
	syscall
	mov	al,byte [rsi+rax-2]
	call	SWAPPIN
	lea 	rsi,[check]
	lea	rdi,[puzzle+5]
	mov	rcx,7
	repe	cmpsq
	jne	MainLp
	mov	rdx,95
	jmp	Succes

SWAPPIN:mov	rdx,rbx
	cmp	al,"A"
	jne	NotUp
	add	rbx,4
	cmp	rbx,16
	cmovae	rbx,rdx
NotUp:	cmp	al,"B"
	jne	NotDwn
	sub	rbx,4
	cmovc	rbx,rdx
NotDwn:	cmp	al,"C"
	jne	NotLft
	test	rbx,3
	jz	Endcll
	dec	rbx
NotLft:	cmp	al,"D"
	jne	Endcll
	inc	rbx
	test	rbx,3
	cmovz	rbx,rdx
Endcll:	mov	ax,"  "
	xchg	ax,word[puzzle+4+rbx*4]
	mov	word[puzzle+4+rdx*4],ax
	ret

Yabasic

dx = 4 : dy = 4 : dxy = dx * dy
dim grid(dx, dy)

dim t(dxy)

for x = 1 to dx
	for y = 1 to dy
		fin = false
		repeat
			i = int(ran(dxy) + 1)
			if t(i) = 0 then
				t(i) = 1
				fin = true
				if i < dxy then
					grid(x, y) = i
				else
					ex = x : ey = y
				end if
			end if
		until(fin = true)
	next y
next x

drawTable()

repeat
	moveTile()
	drawTable()
until(finish())

print "\n\n\nNumber of movements: ",mov,"\nEnd\n"

sub finish()
	local x, y, v

	for y = 1 to dy
		for x = 1 to dx
			v = v + 1
			if (v < dxy) and (grid(x, y) <> v) return false
		next x
	next y
	return true
end sub

sub moveTile()
	local direction$

	direction$ = inkey$

	switch direction$
		case "up": if (ey + 1) < (dy + 1) then grid(ex, ey) = grid(ex, ey + 1) : ey = ey + 1  end if : break
		case "down": if (ey - 1) > 0 then grid(ex, ey) = grid(ex, ey - 1) : ey = ey - 1  end if : break
		case "right": if (ex - 1) > 0 then grid(ex, ey) = grid(ex - 1, ey) : ex = ex - 1  end if : break
		case "left": if (ex + 1) < (dx + 1) then grid(ex, ey) = grid(ex + 1, ey) : ex = ex + 1  end if : break
		default: return : break
	end switch
	mov = mov + 1
	grid(ex, ey) = 0
end sub

sub drawTable()
	local x, y

	clear screen

	print "   Use the cursor keys"

	for x = 1 to dx
		for y = 1 to dy
			print at(x * 3, y * 2);
			if grid(x, y) then
				print color("yellow","magenta") grid(x, y) using "##"
			else
				print "  "
			end if
		next y
	next x
end sub

Adaptation from Phix solution

board$ = "123456789ABCDEF0"
solve$ = board$
pos = 16

sub print_board()
    local i, n$

    clear screen
    for i = 1 to len(board$)
    	if i = pos then
            print "   ";
    	else
    	    n$ = str$(dec(mid$(board$, i, 1)), "###")
    	    print n$;
        end if
        if mod(i, 4) = 0 print
    next
    print
end sub

sub move(d)
    local new_pos, delta(4)

    delta(1) = 4 : delta(2) = 1 : delta(3) = -1 : delta(4) = -4

    new_pos = pos + delta(d)
    if new_pos >= 1 and new_pos <= 16 and (mod(pos, 4) = mod(new_pos, 4) or floor((pos - 1) / 4) = floor((new_pos - 1) / 4)) then
    	mid$(board$, pos, 1) = mid$(board$, new_pos, 1)
    	mid$(board$, new_pos, 1) = "0"
        pos = new_pos
    end if
end sub

for i = 1 to 100 : move(int(ran(4))+1) : next
do
    print_board()
    if board$ = solve$ break
    c = ((instr("esc  up   left rightdown ", inkey$) - 1) / 5)
    if c < 1 break
    move(c)
loop
print "solved!\n"