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{{task|Sorting Algorithms}} {{Sorting Algorithm}}
;Task: Sort an array of integers (of any convenient size) into ascending order using [[wp:Pancake sorting|Pancake sorting]].
In short, instead of individual elements being sorted, the only operation allowed is to "flip" one end of the list, like so: Before: '''6 7 8 9''' 2 5 3 4 1 After: '''9 8 7 6''' 2 5 3 4 1
Only one end of the list can be flipped; this should be the low end, but the high end is okay if it's easier to code or works better, but it '''must''' be the same end for the entire solution. (The end flipped can't be arbitrarily changed.)
Show both the initial, unsorted list and the final sorted list. (Intermediate steps during sorting are optional.) Optimizations are optional (but recommended).
For more information on pancake sorting, see [[wp:Pancake sorting|the Wikipedia entry]].
See also:
- [[Number reversal game]]
- [[Topswops]]
Ada
with Ada.Text_IO;
procedure Pancake_Sort is
generic
type Element_Type is private;
type Index_Type is range <>;
type Array_Type is array (Index_Type range <>) of Element_Type;
with function ">" (Left, Right : Element_Type) return Boolean is <>;
procedure Pancake_Sort (Data: in out Array_Type);
procedure Pancake_Sort (Data: in out Array_Type) is
procedure Flip (Up_To : in Index_Type) is
Temp : constant Array_Type := Data (Data'First .. Up_To);
begin
for I in Temp'Range loop
Data (I) := Temp (Temp'First + Up_To - I);
end loop;
end Flip;
Max_Index : Index_Type;
begin
for I in reverse Data'First + 1 .. Data'Last loop
Max_Index := Data'First;
for A in Data'First + 1 .. I loop
if Data(A) > Data (Max_Index) then
Max_Index := A;
end if;
end loop;
if Max_Index /= I then
if Max_Index > Data'First then
Flip (Max_Index);
end if;
Flip (I);
end if;
end loop;
end Pancake_Sort;
type Integer_Array is array (Positive range <>) of Integer;
procedure Int_Pancake_Sort is new Pancake_Sort (Integer, Positive, Integer_Array);
Test_Array : Integer_Array := (3, 14, 1, 5, 9, 2, 6, 3);
begin
Int_Pancake_Sort (Test_Array);
for I in Test_Array'Range loop
Ada.Text_IO.Put (Integer'Image (Test_Array (I)));
end loop;
Ada.Text_IO.New_Line;
end Pancake_Sort;
Output:
1 2 3 3 5 6 9 14
ALGOL 68
{{trans|Euphoria}}
PROC flip = ([]INT s, INT n) []INT:
BEGIN
[UPB s]INT ss := s;
INT temp;
FOR i TO n OVER 2 DO
temp := ss[i];
ss[i] := ss[n-i+1];
ss[n-i+1] := temp
OD;
ss
END;
PROC pancake sort = ([]INT s) []INT:
BEGIN
INT m;
[UPB s]INT ss := s;
FOR i FROM UPB s DOWNTO 2 DO
m := 1;
FOR j FROM 2 TO i DO
IF ss[j] > ss[m] THEN
m := j
FI
OD;
IF m < i THEN
IF m > 1 THEN
ss := flip (ss,m)
FI;
ss := flip (ss,i)
FI
OD;
ss
END;
[10]INT s;
FOR i TO UPB s DO
s[i] := ENTIER (next random * 100-50)
OD;
printf (($"Pancake sort demonstration"l$));
printf (($"unsorted: "10(g(4) )l$, s));
printf (($"sorted: "10(g(4) )l$, pancake sort(s)))
{{out}}
Pancake sort demonstration
unsorted: -26 +41 -4 +21 +8 -2 +31 -47 -41 -7
sorted: -47 -41 -26 -7 -4 -2 +8 +21 +31 +41
AutoHotkey
;---------------------------------------------------------------------------
Loop { ; test loop
;---------------------------------------------------------------------------
Loop, % Data0 := 10
Random, Data%A_Index%, 10, 99
Unsorted := Array2List("Data")
PancakeSort("Data")
Sorted := Array2List("Data")
MsgBox, 1, Pancake Sort, %Unsorted%`n%Sorted%
IfMsgBox, Cancel, Break
}
;---------------------------------------------------------------------------
PancakeSort(Array) { ; implementation of pancake sort algorithm
;---------------------------------------------------------------------------
Loop, % %Array%0 - 1 {
m := 0
Loop, % s := %Array%0 - A_Index + 1
If (m <= %Array%%A_Index%)
m := %Array%%A_Index%, p := A_Index
If (p < s) && (p > 1)
Flip(Array, p)
If (p < s)
Flip(Array, s)
}
}
;---------------------------------------------------------------------------
Flip(Array, n) { ; flip the first n members of Array
;---------------------------------------------------------------------------
Loop, % x := n // 2 {
i := n - A_Index + 1
%Array%%i% := (%Array%%A_Index% "", %Array%%A_Index% := %Array%%i%)
}
}
;---------------------------------------------------------------------------
Array2List(Array) { ; returns a space separated list from an array
;---------------------------------------------------------------------------
Loop, % %Array%0
List .= (A_Index = 1 ? "" : " ") %Array%%A_Index%
Return, List
}
BASIC
Text
{{works with|QBasic}}
RANDOMIZE TIMER
DIM nums(9) AS INTEGER
DIM L0 AS INTEGER, L1 AS INTEGER, n AS INTEGER
'initial values
FOR L0 = 0 TO 9
nums(L0) = L0
NEXT
'scramble
FOR L0 = 9 TO 1 STEP -1
n = INT(RND * (L0)) + 1
IF n <> L0 THEN SWAP nums(n), nums(L0)
NEXT
'display initial condition
FOR L0 = 0 TO 9
PRINT nums(L0);
NEXT
PRINT
FOR L1 = 9 TO 1 STEP -1
n = 0
FOR L0 = 1 TO L1
IF nums(n) < nums(L0) THEN n = L0
NEXT
IF (n < L1) THEN
IF (n > 0) THEN
FOR L0 = 0 TO (n \ 2)
SWAP nums(L0), nums(n - L0)
NEXT
FOR L0 = 0 TO 9
PRINT nums(L0);
NEXT
PRINT
END IF
FOR L0 = 0 TO (L1 \ 2)
SWAP nums(L0), nums(L1 - L0)
NEXT
FOR L0 = 0 TO 9
PRINT nums(L0);
NEXT
PRINT
END IF
NEXT
Sample output: 0 4 6 1 8 7 2 5 3 9 8 1 6 4 0 7 2 5 3 9 3 5 2 7 0 4 6 1 8 9 7 2 5 3 0 4 6 1 8 9 1 6 4 0 3 5 2 7 8 9 6 1 4 0 3 5 2 7 8 9 2 5 3 0 4 1 6 7 8 9 5 2 3 0 4 1 6 7 8 9 1 4 0 3 2 5 6 7 8 9 4 1 0 3 2 5 6 7 8 9 2 3 0 1 4 5 6 7 8 9 3 2 0 1 4 5 6 7 8 9 1 0 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9
Graphics
This is a graphical variation of the above.
RANDOMIZE TIMER
CONST delay = .1 'controls display speed
DIM nums(14) AS INTEGER
DIM L0 AS INTEGER, L1 AS INTEGER, n AS INTEGER, ttmp AS SINGLE
'initial values
FOR L0 = 0 TO 14
nums(L0) = L0
NEXT
'scramble
FOR L0 = 14 TO 1 STEP -1
n = INT(RND * (L0)) + 1
IF n <> L0 THEN SWAP nums(n), nums(L0)
NEXT
'display initial condition
CLS
GOSUB displayer
FOR L1 = 14 TO 1 STEP -1
n = 0
FOR L0 = 1 TO L1
IF nums(n) < nums(L0) THEN n = L0
NEXT
IF (n < L1) THEN
IF (n > 0) THEN
FOR L0 = 0 TO (n \ 2)
SWAP nums(L0), nums(n - L0)
NEXT
GOSUB displayer
END IF
FOR L0 = 0 TO (L1 \ 2)
SWAP nums(L0), nums(L1 - L0)
NEXT
GOSUB displayer
END IF
NEXT
COLOR 7
END
displayer:
LOCATE 1, 1
FOR L0 = 0 TO 14
COLOR nums(L0) + 1
IF nums(L0) < 10 THEN PRINT " ";
PRINT RTRIM$(LTRIM$(STR$(nums(L0)))); STRING$(nums(L0), 219); SPACE$(20)
NEXT
ttmp = TIMER
DO WHILE TIMER < ttmp + delay: LOOP
RETURN
Sample output:
[[File:Pancake.gif]]
BBC BASIC
DIM test(9)
test() = 4, 65, 2, -31, 0, 99, 2, 83, 782, 1
PROCpancakesort(test())
FOR i% = 0 TO 9
PRINT test(i%) ;
NEXT
PRINT
END
DEF PROCpancakesort(a())
LOCAL i%, j%, m%
FOR i% = DIM(a(),1)+1 TO 2 STEP -1
m% = 0
FOR j% = 1 TO i%-1
IF a(j%) > a(m%) m% = j%
NEXT
m% += 1
IF m% < i% THEN
IF m% > 1 PROCflip(a(), m%)
PROCflip(a(), i%)
ENDIF
NEXT
ENDPROC
DEF PROCflip(a(), n%)
IF n% < 2 ENDPROC
LOCAL i%
n% -= 1
FOR i% = 0 TO n% DIV 2
SWAP a(i%), a(n%-i%)
NEXT
ENDPROC
'''Output:'''
-31 0 1 2 2 4 65 83 99 782
C
'''The function that sorts:'''
int pancake_sort(int *list, unsigned int length) { //If it's less than 2 long, just return it as sorting isn't really needed... if(length<2) return 0; int i,a,max_num_pos,moves; moves=0; for(i=length;i>1;i--) { //Find position of the max number in pos(0) to pos(i) max_num_pos=0; for(a=0;a<i;a++) { if(list[a]>list[max_num_pos]) max_num_pos=a; } if(max_num_pos==i-1) //It's where it need to be, skip continue; //Get the found max number to the beginning of the list (unless it already is) if(max_num_pos) { moves++; do_flip(list, length, max_num_pos+1); } //And then move it to the end of the range we're working with (pos(0) to pos(i)) moves++; do_flip(list, length, i); //Then everything above list[i-1] is sorted and don't need to be touched } return moves; }
Where do_flip() is a simple function to flip a part of an array:
void do_flip(int *list, int length, int num) { int swap; int i=0; for(i;i<--num;i++) { swap=list[i]; list[i]=list[num]; list[num]=swap; } }
'''Testing the function:'''
int main(int argc, char **argv) { //Just need some random numbers. I chose <100 int list[9]; int i; srand(time(NULL)); for(i=0;i<9;i++) list[i]=rand()%100; //Print list, run code and print it again displaying number of moves printf("\nOriginal: "); print_array(list, 9); int moves = pancake_sort(list, 9, 1); printf("\nSorted: "); print_array(list, 9); printf(" - with a total of %d moves\n", moves); }
C++
#include <algorithm> #include <iostream> #include <iterator> #include <vector> // pancake sort template (calls predicate to determine order) template <typename BidIt, typename Pred> void pancake_sort(BidIt first, BidIt last, Pred order) { if (std::distance(first, last) < 2) return; // no sort needed for (; first != last; --last) { BidIt mid = std::max_element(first, last, order); if (mid == last - 1) { continue; // no flips needed } if (first != mid) { std::reverse(first, mid + 1); // flip element to front } std::reverse(first, last); // flip front to final position } } // pancake sort template (ascending order) template <typename BidIt> void pancake_sort(BidIt first, BidIt last) { pancake_sort(first, last, std::less<typename std::iterator_traits<BidIt>::value_type>()); } int main() { std::vector<int> data; for (int i = 0; i < 20; ++i) { data.push_back(i); // generate test data } std::random_shuffle(data.begin(), data.end()); // scramble data std::copy(data.begin(), data.end(), std::ostream_iterator<int>(std::cout, " ")); std::cout << "\n"; pancake_sort(data.begin(), data.end()); // ascending pancake sort std::copy(data.begin(), data.end(), std::ostream_iterator<int>(std::cout, " ")); std::cout << "\n"; }
Output:
4 10 11 15 14 16 17 1 6 9 3 7 19 2 0 12 5 18 13 8
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
C#
<lang C sharp|C#>
public static class PancakeSorter
{
public static void Sort
## Clojure
```clojure
(defn pancake-sort
[arr]
(if (= 1 (count arr))
arr
(when-let [mx (apply max arr)]
(let [tk (split-with #(not= mx %) arr)
tail (second tk)
torev (concat (first tk) (take 1 tail))
head (reverse torev)]
(cons mx (pancake-sort (concat (drop 1 head) (drop 1 tail))))))))
Common Lisp
(defun pancake-sort (seq) "A destructive version of Pancake Sort that works with either lists or arrays of numbers." (defun flip (lst index) (setf (subseq lst 0 index) (reverse (subseq lst 0 index)))) (loop with lst = (coerce seq 'list) for i from (length lst) downto 2 for index = (position (apply #'max (subseq lst 0 i)) lst) do (unless (= index 0) (flip lst (1+ index))) (flip lst i) finally (return (coerce lst (type-of seq)))))
Output:
CL-USER> (pancake-sort '(6 7 8 9 2 5 3 4 1)) ;list (1 2 3 4 5 6 7 8 9) CL-USER> (pancake-sort #(6 7 8 9 2 5 3 4 1)) ;array #(1 2 3 4 5 6 7 8 9) CL-USER> (pancake-sort #(6.5 7.5 8 9 2 5 3 4 1.0)) ;array with integer and floating point values #(1.0 2 3 4 5 6.5 7.5 8 9)
D
{{trans|Python}}
import std.stdio, std.algorithm; void pancakeSort(bool tutor=false, T)(T[] data) { foreach_reverse (immutable i; 2 .. data.length + 1) { immutable maxIndex = i - data[0 .. i].minPos!q{a > b}.length; if (maxIndex + 1 != i) { if (maxIndex != 0) { static if (tutor) writeln("With: ", data, " doflip ", maxIndex + 1); data[0 .. maxIndex + 1].reverse(); } static if (tutor) writeln("With: ", data, " doflip ", i); data[0 .. i].reverse(); } } } void main() { auto data = "769248135".dup; data.pancakeSort!true; data.writeln; }
{{out}}
With: 769248135 doflip 3
With: 967248135 doflip 9
With: 531842769 doflip 4
With: 813542769 doflip 8
With: 672453189 doflip 2
With: 762453189 doflip 7
With: 135426789 doflip 3
With: 531426789 doflip 5
With: 241356789 doflip 2
With: 421356789 doflip 4
With: 312456789 doflip 3
With: 213456789 doflip 2
123456789
Eiffel
class
PANCAKE_SORT [G -> COMPARABLE]
feature {NONE}
arraymax (array: ARRAY [G]; upper: INTEGER): INTEGER
--- Max item of 'array' between index 1 and 'upper'.
require
upper_index_positive: upper >= 0
array_not_void: array /= Void
local
i: INTEGER
cur_max: G
do
from
i := 1
cur_max := array.item (i)
Result := i
until
i + 1 > upper
loop
if array.item (i + 1) > cur_max then
cur_max := array.item (i + 1)
Result := i + 1
end
i := i + 1
end
ensure
Index_positive: Result > 0
end
reverse_array (ar: ARRAY [G]; upper: INTEGER): ARRAY [G]
-- Array reversed from index one to upper.
require
upper_positive: upper > 0
ar_not_void: ar /= Void
local
i, j: INTEGER
new_array: ARRAY [G]
do
create Result.make_empty
Result.deep_copy (ar)
from
i := 1
j := upper
until
i > j
loop
Result [i] := ar [j]
Result [j] := ar [i]
i := i + 1
j := j - 1
end
ensure
same_length: ar.count = Result.count
end
sort (ar: ARRAY [G]): ARRAY [G]
-- Sorted array in ascending order.
local
i: INTEGER
do
create Result.make_empty
Result.deep_copy (ar)
from
i := ar.count
until
i = 1
loop
Result := reverse_array (reverse_array (Result, arraymax (Result, i)), i)
i := i - 1
end
ensure
same_length: ar.count = Result.count
Result_sorted: is_sorted (Result)
end
is_sorted (ar: ARRAY [G]): BOOLEAN
--- Is 'ar' sorted in ascending order?
require
ar_not_empty: ar.is_empty = False
local
i: INTEGER
do
Result := True
from
i := ar.lower
until
i = ar.upper
loop
if ar [i] > ar [i + 1] then
Result := False
end
i := i + 1
end
end
feature
pancake_sort (ar: ARRAY [G]): ARRAY [G]
do
Result := sort (ar)
end
end
Test:
class
APPLICATION
create
make
feature
make
do
test := <<1, 27, 32, 99, 1, -7, 3, 5>>
create sorter
io.put_string ("Unsorted: ")
across
test as ar
loop
io.put_string (ar.item.out + " ")
end
io.put_string ("%NSorted: ")
test := sorter.pancake_sort(test)
across
test as ar
loop
io.put_string (ar.item.out + " ")
end
end
test: ARRAY [INTEGER]
sorter: PANCAKE_SORT[INTEGER]
end
{{out}}
Unsorted: 1 27 32 99 1 -7 3 5
Sorted: -7 1 1 3 5 27 32 99
Elena
ELENA 4.1 : {{trans|C#}}
import extensions;
extension op
{
pancakeSort()
{
var list := self.clone();
int i := list.Length;
if (i < 2) { ^ self };
while (i > 1)
{
int max_num_pos := 0;
int a := 0;
while (a < i)
{
if (list[a] > list[max_num_pos])
{
max_num_pos := a
};
a += 1
};
if (max_num_pos == i - 1)
{
}
else
{
if (max_num_pos > 0)
{
list.flip(list.Length, max_num_pos + 1)
};
list.flip(list.Length, i)
};
i -= 1
};
^ list
}
flip(int length, int num)
{
int i := 0;
int count := num - 1;
while (i < count)
{
var swap := self[i];
self[i] := self[count];
self[count] := swap;
i += 1;
count -= 1
}
}
}
public program()
{
var list := new int[]::(6, 7, 8, 9, 2, 5, 3, 4, 1);
console.printLine("before:", list.asEnumerable());
console.printLine("after :", list.pancakeSort().asEnumerable())
}
{{out}}
before:6,7,8,9,2,5,3,4,1
after :1,2,3,4,5,6,7,8,9
Elixir
defmodule Sort do def pancake_sort(list) when is_list(list), do: pancake_sort(list, length(list)) defp pancake_sort(list, 0), do: list defp pancake_sort(list, limit) do index = search_max(list, limit) flip(list, index) |> flip(limit) |> pancake_sort(limit-1) end defp search_max([h | t], limit), do: search_max(t, limit, 2, h, 1) defp search_max(_, limit, index, _, max_index) when limit<index, do: max_index defp search_max([h | t], limit, index, max, max_index) do if h > max, do: search_max(t, limit, index+1, h, index), else: search_max(t, limit, index+1, max, max_index) end defp flip(list, n), do: flip(list, n, []) defp flip(list, 0, reverse), do: reverse ++ list defp flip([h | t], n, reverse) do flip(t, n-1, [h | reverse]) end end IO.inspect list = Enum.shuffle(1..9) IO.inspect Sort.pancake_sort(list)
{{out}}
[3, 7, 2, 8, 6, 4, 9, 1, 5]
[1, 2, 3, 4, 5, 6, 7, 8, 9]
Euphoria
function flip(sequence s, integer n)
object temp
for i = 1 to n/2 do
temp = s[i]
s[i] = s[n-i+1]
s[n-i+1] = temp
end for
return s
end function
function pancake_sort(sequence s)
integer m
for i = length(s) to 2 by -1 do
m = 1
for j = 2 to i do
if compare(s[j], s[m]) > 0 then
m = j
end if
end for
if m < i then
if m > 1 then
s = flip(s,m)
end if
s = flip(s,i)
end if
end for
return s
end function
constant s = rand(repeat(100,10))
? s
? pancake_sort(s)
Output:
{24,32,100,15,8,34,50,79,46,52}
{8,15,24,32,34,46,50,52,79,100}
=={{header|F_Sharp|F#}}==
open System let show data = data |> Array.iter (printf "%d ") ; printfn "" let split (data: int[]) pos = data.[0..pos], data.[(pos+1)..] let flip items pos = let lower, upper = split items pos Array.append (Array.rev lower) upper let pancakeSort items = let rec loop data limit = if limit <= 0 then data else let lower, upper = split data limit let indexOfMax = lower |> Array.findIndex ((=) (Array.max lower)) let partialSort = Array.append (flip lower indexOfMax |> Array.rev) upper loop partialSort (limit-1) loop items ((Array.length items)-1)
Usage: pancakeSort [|31; 41; 59; 26; 53; 58; 97; 93; 23; 84|] |> show
Output:
23 26 31 41 53 58 59 84 93 97
Fortran
{{works with|Fortran|90 and later}}
program Pancake_Demo
implicit none
integer :: list(8) = (/ 1, 4, 7, 2, 5, 8, 3, 6 /)
call Pancake_sort(list)
contains
subroutine Pancake_sort(a)
integer, intent(in out) :: a(:)
integer :: i, maxpos
write(*,*) a
do i = size(a), 2, -1
! Find position of max number between index 1 and i
maxpos = maxloc(a(1:i), 1)
! is it in the correct position already?
if (maxpos == i) cycle
! is it at the beginning of the array? If not flip array section so it is
if (maxpos /= 1) then
a(1:maxpos) = a(maxpos:1:-1)
write(*,*) a
end if
! Flip array section to get max number to correct position
a(1:i) = a(i:1:-1)
write(*,*) a
end do
end subroutine
end program Pancake_Demo
Output:
1 4 7 2 5 8 3 6
8 5 2 7 4 1 3 6
6 3 1 4 7 2 5 8
7 4 1 3 6 2 5 8
5 2 6 3 1 4 7 8
6 2 5 3 1 4 7 8
4 1 3 5 2 6 7 8
5 3 1 4 2 6 7 8
2 4 1 3 5 6 7 8
4 2 1 3 5 6 7 8
3 1 2 4 5 6 7 8
2 1 3 4 5 6 7 8
1 2 3 4 5 6 7 8
FreeBASIC
' version 11-04-2017
' compile with: fbc -s console
' for boundry checks on array's compile with: fbc -s console -exx
' direction = 1, (default) sort ascending
' direction <> 1 sort descending
' show = 0, (default) do not show sorting
' show <> 0, show sorting
Sub pancake_sort(a() As Long,direction As Long = 1, show As Long = 0)
' array's can have subscript range from -2147483648 to +2147483647
Dim As Long i, j, n
Dim As Long lb = LBound(a)
Dim As Long ub = UBound(a)
If show <> 0 Then ' show initial state
For j = lb To ub
Print Using "####"; a(j);
Next
Print
End If
For i = ub To lb +1 Step -1
n = lb
For j = lb +1 To i
If direction = 1 Then
If a(n) < a(j) Then n = j
Else
If a(n) > a(j) Then n = j
End If
Next
If n < i Then
If n > lb Then
For j = lb To lb + ((n - lb) \ 2)
Swap a(j), a(lb + n - j)
Next
If show <> 0 Then
For j = lb To ub
Print Using "####"; a(j);
Next
Print
End If
End If
For j = lb To lb + ((i - lb) \ 2)
Swap a(j), a(lb + i - j)
Next
If show <> 0 Then
For j = lb To ub
Print Using "####"; a(j);
Next
Print
End If
End If
Next
End Sub
' ------=< MAIN >=------
Dim As Long i, array(-7 To 7)
Dim As Long lb = LBound(array)
Dim As Long ub = UBound(array)
Randomize Timer
For i = lb To ub : array(i) = i : Next
For i = lb To ub ' little shuffle
Swap array(i), array(Int(Rnd * (ub - lb +1) + lb))
Next
Print "unsorted ";
For i = lb To ub
Print Using "####"; array(i);
Next
Print : Print
pancake_sort(array())
Print " sorted ";
For i = lb To ub
Print Using "####"; array(i);
Next
Print : Print
Dim As Long l(10 To ...) = {0, -30, 20, -10, 0, 10, -20}
pancake_sort(l(),0,1) ' sort array l, ascending and show process
Print : Print " sorted l()";
For i = LBound(l) To UBound(l)
Print Using "####"; l(i);
Next
Print
' empty keyboard buffer
While Inkey <> "" : Wend
Print : Print "hit any key to end program"
Sleep
End
{{out}}
unsorted -1 -4 1 6 7 5 2 -3 4 -5 -2 -6 0 3 -7
sorted -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7
0 -30 20 -10 0 10 -20
-30 0 20 -10 0 10 -20
-20 10 0 -10 20 0 -30
0 20 -10 0 10 -20 -30
-10 20 0 0 10 -20 -30
10 0 0 20 -10 -20 -30
0 10 0 20 -10 -20 -30
20 0 10 0 -10 -20 -30
0 20 10 0 -10 -20 -30
10 20 0 0 -10 -20 -30
20 10 0 0 -10 -20 -30
sorted l() 20 10 0 0 -10 -20 -30
Go
package main import "fmt" func main() { list := pancake{31, 41, 59, 26, 53, 58, 97, 93, 23, 84} fmt.Println("unsorted:", list) list.sort() fmt.Println("sorted! ", list) } type pancake []int func (a pancake) sort() { for uns := len(a) - 1; uns > 0; uns-- { // find largest in unsorted range lx, lg := 0, a[0] for i := 1; i <= uns; i++ { if a[i] > lg { lx, lg = i, a[i] } } // move to final position in two flips a.flip(lx) a.flip(uns) } } func (a pancake) flip(r int) { for l := 0; l < r; l, r = l+1, r-1 { a[l], a[r] = a[r], a[l] } }
Output:
unsorted: [31 41 59 26 53 58 97 93 23 84]
sorted! [23 26 31 41 53 58 59 84 93 97]
Groovy
This formulation of the pancake sort achieves stability by picking the last index (rather than, say, the first) in the remaining sublist that matches the max value of the remaining sublist. Performance is enhanced somewhat by not flipping if the ''flipPoint'' is already at the end of the remaining sublist.
def makeSwap = { a, i, j = i+1 -> print "."; a[[j,i]] = a[[i,j]] } def flip = { list, n -> (0..<((n+1)/2)).each { makeSwap(list, it, n-it) } } def pancakeSort = { list -> def n = list.size() (1..<n).reverse().each { i -> def max = list[0..i].max() def flipPoint = (i..0).find{ list[it] == max } if (flipPoint != i) { flip(list, flipPoint) flip(list, i) } } list }
Test:
println (pancakeSort([23,76,99,58,97,57,35,89,51,38,95,92,24,46,31,24,14,12,57,78,4])) println (pancakeSort([88,18,31,44,4,0,8,81,14,78,20,76,84,33,73,75,82,5,62,70,12,7,1])) println () println (pancakeSort([10, 10.0, 10.00, 1])) println (pancakeSort([10, 10.00, 10.0, 1])) println (pancakeSort([10.0, 10, 10.00, 1])) println (pancakeSort([10.0, 10.00, 10, 1])) println (pancakeSort([10.00, 10, 10.0, 1])) println (pancakeSort([10.00, 10.0, 10, 1]))
The use of decimals and integers that compare as equal demonstrates, but of course not '''prove''', that the sort is stable.
Output:
..........................................................................................................................................[4, 12, 14, 23, 24, 24, 31, 35, 38, 46, 51, 57, 57, 58, 76, 78, 89, 92, 95, 97, 99]
............................................................................................................................................................................................................[0, 1, 4, 5, 7, 8, 12, 14, 18, 20, 31, 33, 44, 62, 70, 73, 75, 76, 78, 81, 82, 84, 88]
...[1, 10, 10.0, 10.00]
...[1, 10, 10.00, 10.0]
...[1, 10.0, 10, 10.00]
...[1, 10.0, 10.00, 10]
...[1, 10.00, 10, 10.0]
...[1, 10.00, 10.0, 10]
Haskell
import Data.List import Control.Arrow import Control.Monad import Data.Maybe dblflipIt :: (Ord a) => [a] -> [a] dblflipIt = uncurry ((reverse.).(++)). first reverse . ap (flip splitAt) (succ. fromJust. (elemIndex =<< maximum)) dopancakeSort :: (Ord a) => [a] -> [a] dopancakeSort xs = dopcs (xs,[]) where dopcs ([],rs) = rs dopcs ([x],rs) = x:rs dopcs (xs,rs) = dopcs $ (init &&& (:rs).last ) $ dblflipIt xs
Example:
*Main> dopancakeSort [3,2,1,0,2] [0,1,2,2,3]
=={{header|Icon}} and {{header|Unicon}}==
procedure main() #: demonstrate various ways to sort a list and string
demosort(pancakesort,[3, 14, 1, 5, 9, 2, 6, 3],"qwerty")
pancakeflip := pancakeflipshow # replace pancakeflip procedure with a variant that displays each flip
pancakesort([3, 14, 1, 5, 9, 2, 6, 3])
end
procedure pancakesort(X,op) #: return sorted list ascending(or descending)
local i,m
op := sortop(op,X) # select how and what we sort
every i := *X to 2 by -1 do { # work back to front
m := 1
every j := 2 to i do
if op(X[m],X[j]) then m := j # find X that belongs @i high (or low)
if i ~= m then { # not already in-place
X := pancakeflip(X,m) # . bring max (min) to front
X := pancakeflip(X,i) # . unsorted portion of stack
}
}
return X
end
procedure pancakeflip(X,tail) #: return X[1:tail] flipped
local i
i := 0
tail := integer(\tail|*X) + 1 | runerr(101,tail)
while X[(i +:= 1) < (tail -:= 1)] :=: X[i] # flip
return X
end
procedure pancakeflipshow(X,tail) #: return X[1:tail] flipped (and display)
local i
i := 0
tail := integer(\tail|*X) + 1 | runerr(101,tail)
while X[(i +:= 1) < (tail -:= 1)] :=: X[i] # flip
every writes(" ["|right(!X,4)|" ]\n") # show X
return X
end
Note: This example relies on [[Sorting_algorithms/Bubble_sort#Icon| the supporting procedures 'sortop', and 'demosort' in Bubble Sort]]. The full demosort exercises the named sort of a list with op = "numeric", "string", ">>" (lexically gt, descending),">" (numerically gt, descending), a custom comparator, and also a string.
Abbreviated sample output:
Sorting Demo using procedure pancakesort
on list : [ 3 14 1 5 9 2 6 3 ]
with op = &null: [ 1 2 3 3 5 6 9 14 ] (0 ms)
...
on string : "qwerty"
with op = &null: "eqrtwy" (0 ms)
The output below shows the flipping:
[ 14 3 1 5 9 2 6 3 ]
[ 3 6 2 9 5 1 3 14 ]
[ 9 2 6 3 5 1 3 14 ]
[ 3 1 5 3 6 2 9 14 ]
[ 6 3 5 1 3 2 9 14 ]
[ 2 3 1 5 3 6 9 14 ]
[ 5 1 3 2 3 6 9 14 ]
[ 3 2 3 1 5 6 9 14 ]
[ 3 2 3 1 5 6 9 14 ]
[ 1 3 2 3 5 6 9 14 ]
[ 3 1 2 3 5 6 9 14 ]
[ 2 1 3 3 5 6 9 14 ]
[ 2 1 3 3 5 6 9 14 ]
[ 1 2 3 3 5 6 9 14 ]
J
{{eff note|J|/:~}}
flip=: C.~ C.@i.@-
unsorted=: #~ 1 , [: >./\. 2 >/\ ]
FlDown=: flip 1 + (i. >./)@unsorted
FlipUp=: flip 1 >. [:+/>./\&|.@(< {.)
pancake=: FlipUp@FlDown^:_
Example use:
(,:pancake) ?~9
1 0 8 7 4 6 3 5 2
0 1 2 3 4 5 6 7 8
See the [[Talk:Sorting_algorithms/Pancake_sort#J_implementation|discussion page]] for illustrations of the other words.
Java
public class PancakeSort { int[] heap; public String toString() { String info = ""; for (int x: heap) info += x + " "; return info; } public void flip(int n) { for (int i = 0; i < (n+1) / 2; ++i) { int tmp = heap[i]; heap[i] = heap[n-i]; heap[n-i] = tmp; } System.out.println("flip(0.." + n + "): " + toString()); } public int[] minmax(int n) { int xm, xM; xm = xM = heap[0]; int posm = 0, posM = 0; for (int i = 1; i < n; ++i) { if (heap[i] < xm) { xm = heap[i]; posm = i; } else if (heap[i] > xM) { xM = heap[i]; posM = i; } } return new int[] {posm, posM}; } public void sort(int n, int dir) { if (n == 0) return; int[] mM = minmax(n); int bestXPos = mM[dir]; int altXPos = mM[1-dir]; boolean flipped = false; if (bestXPos == n-1) { --n; } else if (bestXPos == 0) { flip(n-1); --n; } else if (altXPos == n-1) { dir = 1-dir; --n; flipped = true; } else { flip(bestXPos); } sort(n, dir); if (flipped) { flip(n); } } PancakeSort(int[] numbers) { heap = numbers; sort(numbers.length, 1); } public static void main(String[] args) { int[] numbers = new int[args.length]; for (int i = 0; i < args.length; ++i) numbers[i] = Integer.valueOf(args[i]); PancakeSort pancakes = new PancakeSort(numbers); System.out.println(pancakes); } }
Example:
$ java PancakeSort 1 2 5 4 3 10 9 8 7 flip(0..5): 10 3 4 5 2 1 9 8 7 flip(0..8): 7 8 9 1 2 5 4 3 10 flip(0..2): 9 8 7 1 2 5 4 3 10 flip(0..7): 3 4 5 2 1 7 8 9 10 flip(0..2): 5 4 3 2 1 7 8 9 10 flip(0..4): 1 2 3 4 5 7 8 9 10 1 2 3 4 5 7 8 9 10 $ java PancakeSort 6 7 2 1 8 9 5 3 4 flip(0..5): 9 8 1 2 7 6 5 3 4 flip(0..8): 4 3 5 6 7 2 1 8 9 flip(0..1): 3 4 5 6 7 2 1 8 9 flip(0..4): 7 6 5 4 3 2 1 8 9 flip(0..6): 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9
JavaScript
Array.prototype.pancake_sort = function () { for (var i = this.length - 1; i >= 1; i--) { // find the index of the largest element not yet sorted var max_idx = 0; var max = this[0]; for (var j = 1; j <= i; j++) { if (this[j] > max) { max = this[j]; max_idx = j; } } if (max_idx == i) continue; // element already in place var new_slice; // flip this max element to index 0 if (max_idx > 0) { new_slice = this.slice(0, max_idx+1).reverse(); for (var j = 0; j <= max_idx; j++) this[j] = new_slice[j]; } // then flip the max element to its place new_slice = this.slice(0, i+1).reverse(); for (var j = 0; j <= i; j++) this[j] = new_slice[j]; } return this; } ary = [7,6,5,9,8,4,3,1,2,0] sorted = ary.concat().pancake_sort();
jq
{{works with|jq|1.4}} This version skips the pair of flips if the focal item is already in place.
def pancakeSort:
def flip(i):
. as $in | ($in[0:i+1]|reverse) + $in[i+1:] ;
# If input is [] then return null
def index_of_max:
. as $in
| reduce range(1; length) as $i
# state: [ix, max]
( [ 0, $in[0] ];
if $in[$i] > .[1] then [ $i, $in[$i] ] else . end )
| .[0] ;
reduce range(0; length) as $iup
(.;
(length - $iup - 1) as $i
| (.[0:$i+1] | index_of_max) as $max
# flip about $max and then about $i unless $i == $max
| if ($i == $max) then .
else flip($max) | flip($i)
end ) ;
'''Example''':
[range(0;2), null, 1.0, 0.5, [1], [2], {"b":1}, {"a":2}, range(2;4)]
| pancakeSort
{{out}}
$ jq -M -c -n -f pancake_sort.jq [null,0,0.5,1,1,2,3,[1],[2],{"a":2},{"b":1}]
Julia
{{works with|Julia|0.6}}
function pancakesort!(arr::Vector{<:Real}) len = length(arr) if len < 2 return arr end for i in len:-1:2 j = indmax(arr[1:i]) if i == j continue end arr[1:j] = reverse(arr[1:j]) arr[1:i] = reverse(arr[1:i]) end return arr end v = rand(-10:10, 10) println("# unordered: $v\n -> ordered: ", pancakesort!(v))
{{out}}
# unordered: [0, -9, -8, 2, -7, 8, 6, -2, -8, 3]
-> ordered: [-9, -8, -8, -7, -2, 0, 2, 3, 6, 8]
Kotlin
// version 1.1.2 class PancakeSort(private val a: IntArray) { init { for (n in a.size downTo 2) { // successively reduce size of array by 1 val index = indexOfMax(n) // find index of largest if (index != n - 1) { // if it's not already at the end if (index > 0) { // if it's not already at the beginning flip(index) // move largest to beginning println("${a.contentToString()} after flipping first ${index + 1}") } flip(n - 1) // move largest to end println("${a.contentToString()} after flipping first $n") } } } private fun indexOfMax(n: Int): Int { var index = 0 for (i in 1 until n) { if (a[i] > a[index]) index = i } return index } private fun flip(index: Int) { var i = index var j = 0 while (j < i) { val temp = a[j] a[j] = a[i] a[i] = temp j++ i-- } } } fun main(args: Array<String>) { val a = intArrayOf(7, 6, 9, 2, 4, 8, 1, 3, 5) println("${a.contentToString()} initially") PancakeSort(a) }
{{out}}
[7, 6, 9, 2, 4, 8, 1, 3, 5] initially
[9, 6, 7, 2, 4, 8, 1, 3, 5] after flipping first 3
[5, 3, 1, 8, 4, 2, 7, 6, 9] after flipping first 9
[8, 1, 3, 5, 4, 2, 7, 6, 9] after flipping first 4
[6, 7, 2, 4, 5, 3, 1, 8, 9] after flipping first 8
[7, 6, 2, 4, 5, 3, 1, 8, 9] after flipping first 2
[1, 3, 5, 4, 2, 6, 7, 8, 9] after flipping first 7
[5, 3, 1, 4, 2, 6, 7, 8, 9] after flipping first 3
[2, 4, 1, 3, 5, 6, 7, 8, 9] after flipping first 5
[4, 2, 1, 3, 5, 6, 7, 8, 9] after flipping first 2
[3, 1, 2, 4, 5, 6, 7, 8, 9] after flipping first 4
[2, 1, 3, 4, 5, 6, 7, 8, 9] after flipping first 3
[1, 2, 3, 4, 5, 6, 7, 8, 9] after flipping first 2
Lua
-- Initialisation math.randomseed(os.time()) numList = {step = 0, sorted = 0} -- Create list of n random values function numList:build (n) self.values = {} for i = 1, n do self.values[i] = math.random(-100, 100) end end -- Return boolean indicating whether the list is in order function numList:isSorted () for i = 2, #self.values do if self.values[i] < self.values[i - 1] then return false end end print("Finished!") return true end -- Display list of numbers on one line function numList:show () if self.step == 0 then io.write("Initial state:\t") else io.write("After step " .. self.step .. ":\t") end for _, v in ipairs(self.values) do io.write(v .. " ") end print() end -- Reverse n values from the left function numList:reverse (n) local flipped = {} for i, v in ipairs(self.values) do if i > n then flipped[i] = v else flipped[i] = self.values[n + 1 - i] end end self.values = flipped end -- Perform one flip of a pancake sort function numList:pancake () local maxPos = 1 for i = 1, #self.values - self.sorted do if self.values[i] > self.values[maxPos] then maxPos = i end end if maxPos == 1 then numList:reverse(#self.values - self.sorted) self.sorted = self.sorted + 1 else numList:reverse(maxPos) end self.step = self.step + 1 end -- Main procedure numList:build(10) numList:show() repeat numList:pancake() numList:show() until numList:isSorted()
{{out}}
Initial state: -67 61 80 47 21 74 43 22 66 -66
After step 1: 80 61 -67 47 21 74 43 22 66 -66
After step 2: -66 66 22 43 74 21 47 -67 61 80
After step 3: 74 43 22 66 -66 21 47 -67 61 80
After step 4: 61 -67 47 21 -66 66 22 43 74 80
After step 5: 66 -66 21 47 -67 61 22 43 74 80
After step 6: 43 22 61 -67 47 21 -66 66 74 80
After step 7: 61 22 43 -67 47 21 -66 66 74 80
After step 8: -66 21 47 -67 43 22 61 66 74 80
After step 9: 47 21 -66 -67 43 22 61 66 74 80
After step 10: 22 43 -67 -66 21 47 61 66 74 80
After step 11: 43 22 -67 -66 21 47 61 66 74 80
After step 12: 21 -66 -67 22 43 47 61 66 74 80
After step 13: 22 -67 -66 21 43 47 61 66 74 80
After step 14: 21 -66 -67 22 43 47 61 66 74 80
After step 15: -67 -66 21 22 43 47 61 66 74 80
Finished!
Maple
flip := proc(arr, i)
local start, temp, icopy;
temp, start, icopy := 0,1,i:
while (start < icopy) do
arr[start], arr[icopy] := arr[icopy], arr[start]:
start:=start+1:
icopy:=icopy-1:
end do:
end proc:
findMax := proc(arr, i)
local Max, j:
Max := 1:
for j from 1 to i do
if arr[j] > arr[Max] then Max := j: end if:
end do:
return Max:
end proc:
pancakesort := proc(arr)
local len,i,Max;
len := numelems(arr):
for i from len to 2 by -1 do
print(arr):
Max := findMax(arr, i):
if (not Max = i) then
flip(arr, Max):
flip(arr, i):
end if:
end do:
print(arr);
end proc:
{{Out|Example}} Input: arr := Array([17,3,72,0,36,2,3,8,40,1]):
[17, 3, 72, 0, 36, 2, 3, 8, 40, 1]
[1, 40, 8, 3, 2, 36, 0, 17, 3, 72]
[3, 17, 0, 36, 2, 3, 8, 1, 40, 72]
[1, 8, 3, 2, 3, 17, 0, 36, 40, 72]
[0, 1, 8, 3, 2, 3, 17, 36, 40, 72]
[3, 2, 3, 0, 1, 8, 17, 36, 40, 72]
[1, 0, 3, 2, 3, 8, 17, 36, 40, 72]
[2, 1, 0, 3, 3, 8, 17, 36, 40, 72]
[0, 1, 2, 3, 3, 8, 17, 36, 40, 72]
[0, 1, 2, 3, 3, 8, 17, 36, 40, 72]
Mathematica
LMaxPosition[ a_, n_ ] := Part[Position[a[[;;n]],Max[a[[;;n]]]],1,1]
SetAttributes[Flip,HoldFirst]; Flip[a_] := Set[a,Reverse[a]]
pancakeSort[a_] : = For[n = Length[a], n > 1, n--,
If[LMaxPosition[a,n] < n,
Flip[a[[;;LMaxPosition[a,n]]]]; Print[a];
Flip[a[[;;n]]]; Print[a];
];
];
(* each major sort step is printed in example usage *)
pancakeSort[{6, 7, 8, 9, 2, 5, 3, 4, 1}]
{9,8,7,6,2,5,3,4,1}
{1,4,3,5,2,6,7,8,9}
{5,3,4,1,2,6,7,8,9}
{2,1,4,3,5,6,7,8,9}
{4,1,2,3,5,6,7,8,9}
{3,2,1,4,5,6,7,8,9}
{3,2,1,4,5,6,7,8,9}
{1,2,3,4,5,6,7,8,9}
=={{header|MATLAB}} / {{header|Octave}}==
function list = pancakeSort(list) for i = (numel(list):-1:2) minElem = list(i); minIndex = i; %Find the min element in the current subset of the list for j = (i:-1:1) if list(j) <= minElem minElem = list(j); minIndex = j; end end %If the element is already in the correct position don't flip if i ~= minIndex %First flip flips the min element in the stack to the top list(minIndex:-1:1) = list(1:minIndex); %Second flip flips the min element into the correct position in %the stack list(i:-1:1) = list(1:i); end end %for end %pancakeSort
Sample Usage:
pancakeSort([4 3 1 5 6 2])
ans =
6 5 4 3 2 1
MAXScript
fn flipArr arr index =
(
local new = #()
for i = index to 1 by -1 do
(
append new arr[i]
)
join new (for i in (index+1) to arr.count collect arr[i])
return new
)
fn pancakeSort arr =
(
if arr.count < 2 then return arr
else
(
for i = arr.count to 1 by -1 do
(
local newArr = for n in 1 to i collect arr[n]
local oldArr = for o in (i+1) to arr.count collect arr[o]
local maxIndices = for m in 1 to (newArr.count) where (newArr[m] == amax newArr) collect m
local lastMaxIndex = maxIndices[maxIndices.count]
newArr = flipArr newArr lastMaxIndex
newArr = flipArr newArr newArr.count
arr = join newArr oldArr
)
return arr
)
)
Output:
a = for i in 1 to 15 collect random 0 20
#(8, 13, 2, 0, 10, 8, 1, 15, 4, 7, 6, 9, 11, 3, 5)
pancakeSort a
#(0, 1, 2, 3, 4, 5, 6, 7, 8, 8, 9, 10, 11, 13, 15)
NetRexx
Sorts integers, decimal numbers and strings because they're all the same to NetRexx.
/* NetRexx */
options replace format comments java crossref symbols nobinary
import java.util.List
runSample(arg)
return
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method pancakeSort(tlist = List, debug = (1 == 0)) private static returns List
if tlist.size() > 1 then do
loop i_ = tlist.size() by -1 while i_ > 1
maxPos = 0
loop a_ = 0 while a_ < i_
if Rexx tlist.get(a_) > Rexx tlist.get(maxPos) then maxPos = a_
end a_
if maxPos = i_ - 1 then iterate i_
if maxPos > 0 then pancakeFlip(tlist, maxPos + 1, debug)
pancakeFlip(tlist, i_, debug)
end i_
end
return tlist
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method pancakeFlip(tlist = List, offset, debug = (1 == 0)) private static returns List
z_ = offset - 1
pl = 3
if debug then do
plx = offset.length()
if plx > pl then pl = plx
say ' flip{1-'offset.right(pl, 0)'} Before:' tlist
end
loop i_ = 0 while i_ < z_
Collections.swap(tlist, i_, z_)
z_ = z_ - 1
end i_
if debug then do
say ' flip{1-'offset.right(pl, 0)'} After:' tlist
end
return tlist
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method runSample(arg) private static
isTrue = (1 == 1)
isFalse = \isTrue
parse arg debug .
if '-debug'.abbrev(debug.lower(), 2) then debug = isTrue
else debug = isFalse
lists = sampleData()
loop il = 1 to lists[0]
clist = words2list(lists[il])
say ' Input:' clist
say 'Output:' pancakeSort(clist, debug)
say
end il
return
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method sampleData() private static
lists = ''
i_ = 0
i_ = i_ + 1; lists[0] = i_; lists[i_] = '1 4 3 5 2 9 8 7 6'
i_ = i_ + 1; lists[0] = i_; lists[i_] = '10 -9 8 -7 6 -5 4 -3 2 -1 0 -10 9 -8 7 -6 5 -4 3 -2 1'
i_ = i_ + 1; lists[0] = i_; lists[i_] = '88 18 31 44 4 0 8 81 14 78 20 76 84 33 73 75 82 5 62 70 12 7 1'
i_ = i_ + 1; lists[0] = i_; lists[i_] = '10 10.0 10.00 1 -10.0 10. -1'
i_ = i_ + 1; lists[0] = i_; lists[i_] = 'To be or not to be that is the question'
i_ = i_ + 1; lists[0] = i_; lists[i_] = '1'
return lists
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method words2list(wordlist) private static returns List
clist = ArrayList()
loop w_ = 1 to wordlist.words()
clist.add(wordlist.word(w_))
end w_
return clist
{{out}}
Input: [1, 4, 3, 5, 2, 9, 8, 7, 6]
Output: [1, 2, 3, 4, 5, 6, 7, 8, 9]
Input: [10, -9, 8, -7, 6, -5, 4, -3, 2, -1, 0, -10, 9, -8, 7, -6, 5, -4, 3, -2, 1]
Output: [-10, -9, -8, -7, -6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
Input: [88, 18, 31, 44, 4, 0, 8, 81, 14, 78, 20, 76, 84, 33, 73, 75, 82, 5, 62, 70, 12, 7, 1]
Output: [0, 1, 4, 5, 7, 8, 12, 14, 18, 20, 31, 33, 44, 62, 70, 73, 75, 76, 78, 81, 82, 84, 88]
Input: [10, 10.0, 10.00, 1, -10.0, 10., -1]
Output: [-10.0, -1, 1, 10.00, 10.0, 10., 10]
Input: [To, be, or, not, to, be, that, is, the, question]
Output: [be, be, is, not, or, question, that, the, to, To]
Input: [1]
Output: [1]
Nim
import algorithm proc pancakeSort[T](list: var openarray[T]) = var length = list.len if length < 2: return var moves = 0 for i in countdown(length, 2): var maxNumPos = 0 for a in 0 .. <i: if list[a] > list[maxNumPos]: maxNumPos = a if maxNumPos == i - 1: continue if maxNumPos > 0: inc moves reverse(list, 0, maxNumPos) inc moves reverse(list, 0, i - 1) var a = @[4, 65, 2, -31, 0, 99, 2, 83, 782] pancakeSort a echo a
Output:
@[-31, 0, 2, 2, 4, 65, 83, 99, 782]
OCaml
let rec sorted = function | [] -> (true) | x::y::_ when x > y -> (false) | x::xs -> sorted xs let rev_until_max li = let rec aux acc greater prefix suffix = function | x::xs when x > greater -> aux (x::acc) x acc xs xs | x::xs -> aux (x::acc) greater prefix suffix xs | [] -> (greater, (prefix @ suffix)) in aux [] min_int [] li li let pancake_sort li = let rec aux i li suffix = let greater, li = rev_until_max li in let suffix = greater :: suffix and li = List.rev li in if sorted li then (li @ suffix), i else aux (succ i) li suffix in aux 0 li [] let print_list li = List.iter (Printf.printf " %d") li; print_newline() let make_rand_list n bound = let rec aux acc i = if i >= n then (acc) else aux ((Random.int bound)::acc) (succ i) in aux [] 0 let () = Random.self_init(); let li = make_rand_list 8 100 in print_list li; let res, n = pancake_sort li in print_list res; Printf.printf " sorted in %d loops\n" n; ;;
PARI/GP
pancakeSort(v)={
my(top=#v);
while(top>1,
my(mx=1,t);
for(i=2,top,if(v[i]>v[mx], mx=i));
if(mx==top, top--; next);
for(i=1,mx\2,
t=v[i];
v[i]=v[mx+1-i];
v[mx+1-i]=t
);
for(i=1,top\2,
t=v[i];
v[i]=v[top+1-i];
v[top+1-i]=t
);
top--
);
v
};
Pascal
Program PancakeSort (output); procedure flip(var b: array of integer; last: integer); var swap, i: integer; begin for i := low(b) to (last - low(b) - 1) div 2 do begin swap := b[i]; b[i] := b[last-(i-low(b))]; b[last-(i-low(b))] := swap; end; end; procedure PancakeSort(var a: array of integer); var i, j, maxpos: integer; begin for i := high(a) downto low(a) do begin // Find position of max number between beginning and i maxpos := i; for j := low(a) to i - 1 do if a[j] > a[maxpos] then maxpos := j; // is it in the correct position already? if maxpos = i then continue; // is it at the beginning of the array? If not flip array section so it is if maxpos <> low(a) then flip(a, maxpos); // Flip array section to get max number to correct position flip(a, i); end; end; var data: array of integer; i: integer; begin setlength(data, 8); Randomize; writeln('The data before sorting:'); for i := low(data) to high(data) do begin data[i] := Random(high(data)); write(data[i]:4); end; writeln; PancakeSort(data); writeln('The data after sorting:'); for i := low(data) to high(data) do begin write(data[i]:4); end; writeln; end.
Output:
:>./PancakeSort
The data before sorting:
3 1 3 2 4 0 2 6
The data after sorting:
0 1 2 2 3 3 4 6
Perl
sub pancake { my @x = @_; for my $idx (0 .. $#x - 1) { my $min = $idx; $x[$min] > $x[$_] and $min = $_ for $idx + 1 .. $#x; next if $x[$min] == $x[$idx]; @x[$min .. $#x] = reverse @x[$min .. $#x] if $x[$min] != $x[-1]; @x[$idx .. $#x] = reverse @x[$idx .. $#x]; } @x; } my @a = map (int rand(100), 1 .. 10); print "Before @a\n"; @a = pancake(@a); print "After @a\n";
Sample output:
Before 57 37 35 35 22 58 70 53 77 15
After 15 22 35 35 37 53 57 58 70 77
Perl 6
sub pancake_sort ( @a is copy ) {
my $endpoint = @a.end;
while $endpoint > 0 and not [<] @a {
my $max_i = [0..$endpoint].max: { @a[$_] };
my $max = @a[$max_i];
if @a[$endpoint] == $max {
$endpoint-- while @a[$endpoint] == $max;
next;
}
# @a[$endpoint] is not $max, so it needs flipping;
# Flip twice if max is not already at the top.
@a[0..$max_i] .= reverse if $max_i != 0;
@a[0..$endpoint] .= reverse;
$endpoint--;
}
return @a;
}
my @data = 6, 7, 2, 1, 8, 9, 5, 3, 4;
say 'input = ' ~ @data;
say 'output = ' ~ @data.&pancake_sort;
Output:
input = 6 7 2 1 8 9 5 3 4
output = 1 2 3 4 5 6 7 8 9
Phix
Copy of [[Sorting_algorithms/Pancake_sort#Euphoria|Euphoria]]
function flip(sequence s, integer n)
for i=1 to floor(n/2) do
{s[i],s[n-i+1]} = {s[n-i+1],s[i]}
end for
return s
end function
function pancake_sort(sequence s)
integer m
for i=length(s) to 2 by -1 do
m = 1
for j=2 to i do
if s[j]>s[m] then
m = j
end if
end for
if m<i then
if m>1 then
s = flip(s,m)
end if
s = flip(s,i)
end if
end for
return s
end function
constant s = shuffle(tagset(10))
? s
? pancake_sort(s)
{{out}}
{2,8,6,1,5,10,3,4,9,7}
{1,2,3,4,5,6,7,8,9,10}
PicoLisp
(de pancake (Lst)
(prog1 (flip Lst (index (apply max Lst) Lst))
(for (L @ (cdr (setq Lst (cdr L))) (cdr L))
(con L (flip Lst (index (apply max Lst) Lst))) ) ) )
Output:
: (trace 'flip)
-> flip
: (pancake (6 7 2 1 8 9 5 3 4))
flip : (6 7 2 1 8 9 5 3 4) 6
flip = (9 8 1 2 7 6 5 3 4)
flip : (8 1 2 7 6 5 3 4) 1
flip = (8 1 2 7 6 5 3 4)
flip : (1 2 7 6 5 3 4) 3
flip = (7 2 1 6 5 3 4)
flip : (2 1 6 5 3 4) 3
flip = (6 1 2 5 3 4)
flip : (1 2 5 3 4) 3
flip = (5 2 1 3 4)
flip : (2 1 3 4) 4
flip = (4 3 1 2)
flip : (3 1 2) 1
flip = (3 1 2)
flip : (1 2) 2
flip = (2 1)
-> (9 8 7 6 5 4 3 2 1)
PL/I
pancake_sort: procedure options (main); /* 23 April 2009 */
declare a(10) fixed, (i, n, loc) fixed binary;
a(1) = 3; a(2) = 9; a(3) = 2; a(4) = 7; a(5) = 10;
a(6) = 1; a(7) = 8; a(8) = 5; a(9) = 4; a(10) = 6;
n = hbound(A,1);
put skip edit (A) (f(5));
do i = 1 to n-1;
loc = max(A, n);
call flip (A, loc);
call flip (A, n);
n = n - 1;
put skip edit (A) (f(5));
end;
max: procedure (A, k) returns (fixed binary);
declare A(*) fixed, k fixed binary;
declare (i, maximum, loc) fixed binary;
maximum = A(1); loc = 1;
do i = 2 to k;
if A(i) > maximum then do; maximum = A(i); loc = i; end;
end;
return (loc);
end max;
flip: procedure (A, k);
declare A(*) fixed, k fixed binary;
declare (i, t) fixed binary;
do i = 1 to (k+1)/2;
t = A(i); A(i) = A(k-i+1); A(k-i+1) = t;
end;
end flip;
end pancake_sort;
Output:
## PowerShell
```PowerShell
Function FlipPancake( [Object[]] $indata, $index = 1 )
{
$data=$indata.Clone()
$datal = $data.length - 1
if( $index -gt 0 )
{
if( $datal -gt $index )
{
$first = $data[ $index..0 ]
$last = $data[ ( $index + 1 )..$datal ]
$data = $first + $last
} else {
$data = $data[ $index..0 ]
}
}
$data
}
Function MaxIdx( [Object[]] $data )
{
$data | ForEach-Object { $max = $data[ 0 ]; $i = 0; $maxi = 0 } { if( $_ -gt $max ) { $max = $_; $maxi = $i }; $i++ } { $maxi }
}
Function PancakeSort( [Object[]] $data, $index = 0 )
{
"unsorted - $data"
$datal = $data.length - 1
if( $datal -gt 0 )
{
for( $i = $datal; $i -gt 0; $i-- )
{
$data = FlipPancake ( FlipPancake $data ( MaxIdx $data[ 0..$i ] ) ) $i
}
}
"sorted - $data"
}
$l = 100; PancakeSort ( 1..$l | ForEach-Object { $Rand = New-Object Random }{ $Rand.Next( 0, $l - 1 ) } )
PureBasic
If OpenConsole()
Define i, j, k, Loops
Dim Pile(9)
;--------------------------------------------------------------
;- Create a Random Pile()
For i=1 To 9 ;- Initiate the Pile
Pile(i)=i
Next
For i=9 To 1 Step -1 ;- Do a Fisher-Yates shuffle
Swap Pile(i),Pile(Random(i-1)+1)
Next
Print("Random Pile() :")
For i=1 To 9
Print(" "+Str(Pile(i)))
Next
;--------------------------------------------------------------
;- Start Sorting
For i=9 To 2 Step -1
If Pile(i)<>i ;- Only Flip it if the current cake need Swapping
Loops+1
j=0
Repeat ;- find place of Pancake(i) in the Pile()
j+1
Until Pile(j)=i
For k=1 To (j/2) ;- Flip it up
Swap Pile(k),Pile(j-k+1)
Next
For k=1 To i/2 ;- Flip in place
Swap Pile(k),Pile(i-k+1)
Next
EndIf
Next
Print(#CRLF$+"Resulting Pile() :")
For i=1 To 9
Print(" "+str(Pile(i)))
Next
Print(#CRLF$+"All done in "+str(Loops)+" loops.")
Print(#CRLF$+#CRLF$+"Press ENTER to quit."): Input()
CloseConsole()
EndIf
'''Output can look like Original Pile() : 9 4 1 8 6 3 2 5 7 Resulting Pile() : 1 2 3 4 5 6 7 8 9 All done in 6 loops.
Press ENTER to quit.
Python
'''The function:'''
tutor = False def pancakesort(data): if len(data) <= 1: return data if tutor: print() for size in range(len(data), 1, -1): maxindex = max(range(size), key=data.__getitem__) if maxindex+1 != size: # This indexed max needs moving if maxindex != 0: # Flip the max item to the left if tutor: print('With: %r doflip %i' % ( ' '.join(str(x) for x in data), maxindex+1 )) data[:maxindex+1] = reversed(data[:maxindex+1]) # Flip it into its final position if tutor: print('With: %r doflip %i' % ( ' '.join(str(x) for x in data), size )) data[:size] = reversed(data[:size]) if tutor: print()
'''A test:'''
if __name__ == '__main__': import random tutor = True data = list('123456789') while data == sorted(data): random.shuffle(data) print('Original List: %r' % ' '.join(data)) pancakesort(data) print('Pancake Sorted List: %r' % ' '.join(data))
'''Sample output:'''
Original List: '6 7 2 1 8 9 5 3 4'
With: '6 7 2 1 8 9 5 3 4' doflip 6
With: '9 8 1 2 7 6 5 3 4' doflip 9
With: '4 3 5 6 7 2 1 8 9' doflip 5
With: '7 6 5 3 4 2 1 8 9' doflip 7
With: '1 2 4 3 5 6 7 8 9' doflip 3
With: '4 2 1 3 5 6 7 8 9' doflip 4
With: '3 1 2 4 5 6 7 8 9' doflip 3
With: '2 1 3 4 5 6 7 8 9' doflip 2
Pancake Sorted List: '1 2 3 4 5 6 7 8 9'
Racket
#lang racket
(define (pancake-sort l)
(define (flip l n) (append (reverse (take l n)) (drop l n)))
(for/fold ([l l]) ([i (in-range (length l) 1 -1)])
(let* ([i2 (cdr (for/fold ([m #f]) ([x l] [j i])
(if (and m (<= x (car m))) m (cons x j))))]
[l (if (zero? i2) l (flip l (add1 i2)))])
(flip l i))))
(pancake-sort (shuffle (range 0 10)))
;; => '(0 1 2 3 4 5 6 7 8 9)
REXX
/*REXX program sorts and displays an array using the pancake sort algorithm. */
call gen /*generate elements in the @. array.*/
call show 'before sort' /*display the BEFORE array elements.*/
say copies('▒', 60) /*display a separator line for eyeballs*/
call pancakeSort # /*invoke the pancake sort. Yummy. */
call show ' after sort' /*display the AFTER array elements. */
exit /*stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
flip: parse arg y; do i=1 for (y+1)%2; yyy=y-i+1; [email protected]; @[email protected]; @.yyy=_; end; return
show: do k=1 for #; say @element right(k,length(#)) arg(1)':' right(@.k,9); end; return
/*──────────────────────────────────────────────────────────────────────────────────────*/
gen: fibs= '-55 -21 -1 -8 -8 -21 -55 0 0' /*some non─positive Fibonacci numbers, */
@element= right('element', 21) /* most Fibs of which are repeated.*/
/* ┌◄─┬──◄─ some paired bread primes which are of the form: (P-3)÷2 and 2∙P+3 */
/* │ │ where P is a prime. Bread primes are related to sandwich & meat primes*/
/* ↓ ↓ ──── ──── ───── ────── ────── ────── ────── ─────── ─────── ─────── ──────*/
bp=2 17 5 29 7 37 13 61 43 181 47 197 67 277 97 397 113 461 137 557 167 677 173 701,
797 1117 307 1237 1597 463 1861 467
$=bp fibs; #=words($) /*combine the two lists; get # of items*/
do j=1 for #; @.j=word($,j); end /*◄─── obtain a number from the $ list.*/
return /* [↑] populate the @. array with #s*/
/*──────────────────────────────────────────────────────────────────────────────────────*/
pancakeSort: procedure expose @.; parse arg N
do N=N by -1 for N-1
[email protected]; ?=1; do j=2 to N; if @.j<=! then iterate
[email protected]; ?=j
end /*j*/
call flip ?; call flip N
end /*N*/
return
{{out|output|text= when using the internally generated numbers:}}
(Shown at three-quarter size.)
element 1 before sort: 2
element 2 before sort: 17
element 3 before sort: 5
element 4 before sort: 29
element 5 before sort: 7
element 6 before sort: 37
element 7 before sort: 13
element 8 before sort: 61
element 9 before sort: 43
element 10 before sort: 181
element 11 before sort: 47
element 12 before sort: 197
element 13 before sort: 67
element 14 before sort: 277
element 15 before sort: 97
element 16 before sort: 397
element 17 before sort: 113
element 18 before sort: 461
element 19 before sort: 137
element 20 before sort: 557
element 21 before sort: 167
element 22 before sort: 677
element 23 before sort: 173
element 24 before sort: 701
element 25 before sort: 797
element 26 before sort: 1117
element 27 before sort: 307
element 28 before sort: 1237
element 29 before sort: 1597
element 30 before sort: 463
element 31 before sort: 1861
element 32 before sort: 467
element 33 before sort: -55
element 34 before sort: -21
element 35 before sort: -1
element 36 before sort: -8
element 37 before sort: -8
element 38 before sort: -21
element 39 before sort: -55
element 40 before sort: 0
element 41 before sort: 0
▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒
element 1 after sort: -55
element 2 after sort: -55
element 3 after sort: -21
element 4 after sort: -21
element 5 after sort: -8
element 6 after sort: -8
element 7 after sort: -1
element 8 after sort: 0
element 9 after sort: 0
element 10 after sort: 2
element 11 after sort: 5
element 12 after sort: 7
element 13 after sort: 13
element 14 after sort: 17
element 15 after sort: 29
element 16 after sort: 37
element 17 after sort: 43
element 18 after sort: 47
element 19 after sort: 61
element 20 after sort: 67
element 21 after sort: 97
element 22 after sort: 113
element 23 after sort: 137
element 24 after sort: 167
element 25 after sort: 173
element 26 after sort: 181
element 27 after sort: 197
element 28 after sort: 277
element 29 after sort: 307
element 30 after sort: 397
element 31 after sort: 461
element 32 after sort: 463
element 33 after sort: 467
element 34 after sort: 557
element 35 after sort: 677
element 36 after sort: 701
element 37 after sort: 797
element 38 after sort: 1117
element 39 after sort: 1237
element 40 after sort: 1597
element 41 after sort: 1861
```
## Ring
```ring
pancakeList = [6, 7, 8, 9, 2, 5, 3, 4, 1]
flag = 0
see "Before :" + nl
for n = 1 to len(pancakeList)
see pancakeList[n] + " "
next
see nl
pancakeSort(pancakeList)
see "After :" + nl
for n = 1 to len(pancakeList)
see pancakeList[n] + " "
next
see nl
func pancakeSort A
n = len(A)
while flag = 0
flag = 1
for i = 1 to n-1
if A[i] < A[i+1]
temp = A[i]
A[i] = A[i+1]
A [i+1] = temp
flag = 0 ok
next
end
return A
```
Output:
```txt
Before :
678925341
After :
987654321
```
## Ruby
```ruby
class Array
def pancake_sort!
num_flips = 0
(self.size-1).downto(1) do |end_idx|
max = self[0..end_idx].max
max_idx = self[0..end_idx].index(max)
next if max_idx == end_idx
if max_idx > 0
self[0..max_idx] = self[0..max_idx].reverse
p [num_flips += 1, self] if $DEBUG
end
self[0..end_idx] = self[0..end_idx].reverse
p [num_flips += 1, self] if $DEBUG
end
self
end
end
p a = (1..9).to_a.shuffle
p a.pancake_sort!
```
'''sample output:'''
```txt
$ ruby -d sorting_pancake.rb
[7, 3, 6, 8, 2, 4, 5, 1, 9]
[1, [8, 6, 3, 7, 2, 4, 5, 1, 9]]
[2, [1, 5, 4, 2, 7, 3, 6, 8, 9]]
[3, [7, 2, 4, 5, 1, 3, 6, 8, 9]]
[4, [6, 3, 1, 5, 4, 2, 7, 8, 9]]
[5, [2, 4, 5, 1, 3, 6, 7, 8, 9]]
[6, [5, 4, 2, 1, 3, 6, 7, 8, 9]]
[7, [3, 1, 2, 4, 5, 6, 7, 8, 9]]
[8, [2, 1, 3, 4, 5, 6, 7, 8, 9]]
[9, [1, 2, 3, 4, 5, 6, 7, 8, 9]]
[1, 2, 3, 4, 5, 6, 7, 8, 9]
```
## Rust
```Rust
fn pancake_sort(v: &mut [T]) {
let len = v.len();
// trivial case -- no flips
if len < 2 {
return;
}
for i in (0..len).rev() {
// find index of the maximum element within `v[0..i]` (inclusive)
let max_index = v.iter()
.take(i + 1)
.enumerate()
.max_by_key(|&(_, elem)| elem)
.map(|(idx, _)| idx)
// safe because we already checked if `v` is empty
.unwrap();
// if `max_index` is not where it's supposed to be
// do two flips to move it to `i`
if max_index != i {
flip(v, max_index);
flip(v, i);
}
}
}
// function to flip a section of a mutable collection from 0..num (inclusive)
fn flip(v: &mut [E], num: usize) {
v[0..num + 1].reverse();
}
fn main() {
// Sort numbers
let mut numbers = [4, 65, 2, -31, 0, 99, 2, 83, 782, 1];
println!("Before: {:?}", numbers);
pancake_sort(&mut numbers);
println!("After: {:?}", numbers);
// Sort strings
let mut strings = ["beach", "hotel", "airplane", "car", "house", "art"];
println!("Before: {:?}", strings);
pancake_sort(&mut strings);
println!("After: {:?}", strings);
}
```
## Sidef
{{trans|Perl}}
```ruby
func pancake(a) {
for idx in ^(a.end) {
var min = idx
for i in (idx+1 .. a.end) { min = i if (a[min] > a[i]) }
next if (a[min] == a[idx])
a[min..a.end] = [a[min..a.end]].reverse...
a[idx..a.end] = [a[idx..a.end]].reverse...
}
return a
}
var arr = 10.of{ 100.irand }
say "Before: #{arr}"
say "After: #{pancake(arr)}"
```
{{out}}
```txt
Before: 61 29 68 15 34 2 32 54 73 43
After: 2 15 29 32 34 43 54 61 68 73
```
## Swift
{{trans|Java}}
```Swift
import Foundation
struct PancakeSort {
var arr:[Int]
mutating func flip(n:Int) {
for i in 0 ..< (n + 1) / 2 {
swap(&arr[n - i], &arr[i])
}
println("flip(0.. \(n)): \(arr)")
}
func minmax(n:Int) -> [Int] {
var xm = arr[0]
var xM = arr[0]
var posm = 0
var posM = 0
for i in 1.. xM) {
xM = arr[i]
posM = i
}
}
return [posm, posM]
}
mutating func sort(var n:Int, var dir:Int) {
if n == 0 {
return
}
let mM = minmax(n)
let bestXPos = mM[dir]
let altXPos = mM[1 - dir]
var flipped = false
if bestXPos == n - 1 {
n--
} else if bestXPos == 0 {
flip(n - 1)
n--
} else if altXPos == n - 1 {
dir = 1 - dir
n--
flipped = true
} else {
flip(bestXPos)
}
sort(n, dir: dir)
if flipped {
flip(n)
}
}
}
let arr = [2, 3, 6, 1, 4, 5, 10, 8, 7, 9]
var a = PancakeSort(arr: arr)
a.sort(arr.count, dir: 1)
println(a.arr)
```
{{out}}
```txt
flip(0.. 6): [10, 5, 4, 1, 6, 3, 2, 8, 7, 9]
flip(0.. 9): [9, 7, 8, 2, 3, 6, 1, 4, 5, 10]
flip(0.. 8): [5, 4, 1, 6, 3, 2, 8, 7, 9, 10]
flip(0.. 6): [8, 2, 3, 6, 1, 4, 5, 7, 9, 10]
flip(0.. 7): [7, 5, 4, 1, 6, 3, 2, 8, 9, 10]
flip(0.. 6): [2, 3, 6, 1, 4, 5, 7, 8, 9, 10]
flip(0.. 2): [6, 3, 2, 1, 4, 5, 7, 8, 9, 10]
flip(0.. 5): [5, 4, 1, 2, 3, 6, 7, 8, 9, 10]
flip(0.. 4): [3, 2, 1, 4, 5, 6, 7, 8, 9, 10]
flip(0.. 2): [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
```
## Tcl
```tcl
package require Tcl 8.5
# Some simple helper procedures
proc flip {nlist n} {
concat [lreverse [lrange $nlist 0 $n]] [lrange $nlist $n+1 end]
}
proc findmax {nlist limit} {
lsearch -exact $nlist [tcl::mathfunc::max {*}[lrange $nlist 0 $limit]]
}
# Simple-minded pancake sort algorithm
proc pancakeSort {nlist {debug ""}} {
for {set i [llength $nlist]} {[incr i -1] > 0} {} {
set j [findmax $nlist $i]
if {$i != $j} {
if {$j} {
set nlist [flip $nlist $j]
if {$debug eq "debug"} {puts [incr flips]>>$nlist}
}
set nlist [flip $nlist $i]
if {$debug eq "debug"} {puts [incr flips]>>$nlist}
}
}
return $nlist
}
```
Demonstrate (with debug mode enabled so it prints intermediate states):
```tcl
puts [pancakeSort {27916 5928 23535 14711 32184 14621 21093 14422 29844 11093} debug]
```
Output:
```txt
1>>32184 14711 23535 5928 27916 14621 21093 14422 29844 11093
2>>11093 29844 14422 21093 14621 27916 5928 23535 14711 32184
3>>29844 11093 14422 21093 14621 27916 5928 23535 14711 32184
4>>14711 23535 5928 27916 14621 21093 14422 11093 29844 32184
5>>27916 5928 23535 14711 14621 21093 14422 11093 29844 32184
6>>11093 14422 21093 14621 14711 23535 5928 27916 29844 32184
7>>23535 14711 14621 21093 14422 11093 5928 27916 29844 32184
8>>5928 11093 14422 21093 14621 14711 23535 27916 29844 32184
9>>21093 14422 11093 5928 14621 14711 23535 27916 29844 32184
10>>14711 14621 5928 11093 14422 21093 23535 27916 29844 32184
11>>14422 11093 5928 14621 14711 21093 23535 27916 29844 32184
12>>5928 11093 14422 14621 14711 21093 23535 27916 29844 32184
5928 11093 14422 14621 14711 21093 23535 27916 29844 32184
```
As you can see, it took 12 flips.
## uBasic/4tH
{{trans|C}}
PRINT "Pancake sort:"
n = FUNC (_InitArray)
PROC _ShowArray (n)
PROC _Pancakesort (n)
PROC _ShowArray (n)
PRINT
END
_Flip PARAM(1)
LOCAL(1)
b@ = 0
DO WHILE b@ < a@
PROC _Swap (b@, a@)
b@ = b@ + 1
a@ = a@ - 1
LOOP
RETURN
_Pancakesort PARAM (1) ' Pancakesort
LOCAL(3)
IF a@ < 2 THEN RETURN
FOR b@ = a@ TO 2 STEP -1
c@ = 0
FOR d@ = 0 TO b@ - 1
IF @(d@) > @(c@) THEN c@ = d@
NEXT
IF c@ = b@ - 1 THEN CONTINUE
IF c@ THEN PROC _Flip (c@)
PROC _Flip (b@ - 1)
NEXT
RETURN
_Swap PARAM(2) ' Swap two array elements
PUSH @(a@)
@(a@) = @(b@)
@(b@) = POP()
RETURN
_InitArray ' Init example array
PUSH 4, 65, 2, -31, 0, 99, 2, 83, 782, 1
FOR i = 0 TO 9
@(i) = POP()
NEXT
RETURN (i)
_ShowArray PARAM (1) ' Show array subroutine
FOR i = 0 TO a@-1
PRINT @(i),
NEXT
PRINT
RETURN
```
## VBA
```vb
'pancake sort
'uses two auxiliary routines "printarray" and "flip"
Public Sub printarray(A)
For i = LBound(A) To UBound(A)
Debug.Print A(i),
Next
Debug.Print
End Sub
Public Sub Flip(ByRef A, p1, p2, trace)
'flip first elements of A (p1 to p2)
If trace Then Debug.Print "we'll flip the first "; p2 - p1 + 1; "elements of the array"
Cut = Int((p2 - p1 + 1) / 2)
For i = 0 To Cut - 1
'flip position i and (n - i + 1)
temp = A(i)
A(i) = A(p2 - i)
A(p2 - i) = temp
Next
End Sub
Public Sub pancakesort(ByRef A(), Optional trace As Boolean = False)
'sort A into ascending order using pancake sort
lb = LBound(A)
ub = UBound(A)
Length = ub - lb + 1
If Length <= 1 Then 'no need to sort
Exit Sub
End If
For i = ub To lb + 1 Step -1
'find position of max. element in subarray A(lowerbound to i)
P = lb
Maximum = A(P)
For j = lb + 1 To i
If A(j) > Maximum Then
P = j
Maximum = A(j)
End If
Next j
'check if maximum is already at end - then we don't need to flip
If P < i Then
'flip the first part of the array up to the maximum so it is at the head - skip if it is already there
If P > 1 Then
Flip A, lb, P, trace
If trace Then printarray A
End If
'now flip again so that it is in its final position
Flip A, lb, i, trace
If trace Then printarray A
End If
Next i
End Sub
'test routine
Public Sub TestPancake(Optional trace As Boolean = False)
Dim A()
A = Array(5, 7, 8, 3, 1, 10, 9, 23, 50, 0)
Debug.Print "Initial array:"
printarray A
pancakesort A, trace
Debug.Print "Final array:"
printarray A
End Sub
```
Sample output:
```txt
testpancake True
Initial array:
5 7 8 3 1 10 9 23 50 0
we'll flip the first 9 elements of the array
50 23 9 10 1 3 8 7 5 0
we'll flip the first 10 elements of the array
0 5 7 8 3 1 10 9 23 50
we'll flip the first 7 elements of the array
10 1 3 8 7 5 0 9 23 50
we'll flip the first 8 elements of the array
9 0 5 7 8 3 1 10 23 50
we'll flip the first 7 elements of the array
1 3 8 7 5 0 9 10 23 50
we'll flip the first 3 elements of the array
8 3 1 7 5 0 9 10 23 50
we'll flip the first 6 elements of the array
0 5 7 1 3 8 9 10 23 50
we'll flip the first 3 elements of the array
7 5 0 1 3 8 9 10 23 50
we'll flip the first 5 elements of the array
3 1 0 5 7 8 9 10 23 50
we'll flip the first 3 elements of the array
0 1 3 5 7 8 9 10 23 50
Final array:
0 1 3 5 7 8 9 10 23 50
```
## zkl
{{trans|Julia}}
```zkl
fcn pancakeSort(a){
foreach i in ([a.len()-1..1,-1]){
j := a.index((0).max(a[0,i+1])); // min for decending sort
if(i != j){ a.swap(0,j); a.swap(0,i); }
}
a
}
```
Note: [offset,count] not [start,stop]
Finding the max index creates a partial list, which isn't good; if it matters use:
```zkl
j := (i+1).reduce('wrap(x,y){ if(a[x]>a[y]) x else y });
```
```zkl
pancakeSort(List(7,6,9,2,4,8,1,3,5)).println();
```
{{out}}
```txt
L(1,2,3,4,5,6,7,8,9)
```
{{omit from|GUISS}}