**⚠️ 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|Games}}

[[wp:Penney's_game|Penney's game]] is a game where two players bet on being the first to see a particular sequence of [[wp:Coin_flipping|heads or tails]] in consecutive tosses of a [[wp:Fair_coin|fair coin]].

It is common to agree on a sequence length of three then one player will openly choose a sequence, for example: Heads, Tails, Heads, or '''HTH''' for short. The other player on seeing the first players choice will choose his sequence. The coin is tossed and the first player to see his sequence in the sequence of coin tosses wins.

;Example: One player might choose the sequence '''HHT''' and the other '''THT'''.

Successive coin tosses of '''HTTHT''' gives the win to the second player as the last three coin tosses are his sequence.

;Task Create a program that tosses the coin, keeps score and plays Penney's game against a human opponent.

- Who chooses and shows their sequence of three should be chosen randomly.
- If going first, the computer should randomly choose its sequence of three.
- If going second, the computer should automatically play [[wp:Penney's_game#Analysis_of_the_three-bit_game|the optimum sequence]].
- Successive coin tosses should be shown.

Show output of a game where the computer chooses first and a game where the user goes first here on this page.

;See also

- [https://www.youtube.com/watch?v=OcYnlSenF04 The Penney Ante Part 1] (Video).
- [https://www.youtube.com/watch?v=U9wak7g5yQA The Penney Ante Part 2] (Video).

## BASIC

=

## Sinclair ZX81 BASIC

= Works with 1k of RAM.

```
=.5 THEN GOTO 100
20 PRINT "YOU PICK FIRST."
30 INPUT P$
40 PRINT "YOU CHOSE ";P$
50 LET C$="H"
60 IF P$(2)="H" THEN LET C$="T"
70 LET C$=C$+P$( TO 2)
80 PRINT "I CHOOSE ";C$
90 GOTO 190
100 PRINT "I PICK FIRST."
110 LET C$=""
120 FOR I=1 TO 3
130 LET C$=C$+"H"
140 IF RND>=.5 THEN LET C$(I)="T"
150 NEXT I
160 PRINT "I CHOOSE ";C$
170 INPUT P$
180 PRINT "YOU CHOSE ";P$
190 LET G$=""
200 IF RND>=.5 THEN GOTO 230
210 LET G$=G$+"H"
220 GOTO 240
230 LET G$=G$+"T"
240 PRINT AT 5,0;G$
250 IF LEN G$<3 THEN GOTO 200
260 IF G$(LEN G$-2 TO )=P$ THEN GOTO 290
270 IF G$(LEN G$-2 TO )=C$ THEN GOTO 310
280 GOTO 200
290 PRINT "YOU WIN"
300 STOP
310 PRINT "I WIN"
```

{{out}}

```
YOU PICK FIRST.
YOU CHOSE HTH
I CHOOSE HHT
HTTTHTTTTHHT
I WIN
```

## Batch File

```
::
::Penney's Game Task from Rosetta Code Wiki
::Batch File Implementation
::
::Please Directly Open the Batch File to play...
::
@echo off
setlocal enabledelayedexpansion
title The Penney's Game Batch File
set cpu=0&set you=0
cls
echo.
echo Penney's Game
echo Batch File Implementation
:main
set you_bet=&set cpu_bet=
echo.&echo --------------------------------------------------------&echo.
echo CPU's Score: %cpu% Your Score: %you%
echo.
<nul set /p "dummy=Heads I start, Tails you start..."
set /a startrnd=%random%%%2
set firsttoss=Tails&set func=optimal
if %startrnd%==1 (set firsttoss=Heads&set func=rndbet)
ping -n 3 localhost >nul
<nul set /p "dummy=. %firsttoss%^!"
echo.&echo.
goto %func%
:rndbet
set /a "seq1=%random%%%2","seq2=%random%%%2","seq3=%random%%%2"
set binary=%seq1%%seq2%%seq3%
set cpu_bet=%binary:1=H%
set cpu_bet=%cpu_bet:0=T%
echo I will bet first. So, my bet sequence will be %cpu_bet%.
:again1
set /p "you_bet=What will be your bet sequence? "
call :validate again1
echo.&echo So, you're feeling lucky on %you_bet%. We'll see...
goto succesivetossing
:optimal
echo Ok. You will bet first.
:again2
set /p "you_bet=What will be your bet sequence? "
call :validate again2
set seq1=%you_bet:~0,1%&set seq2=%you_bet:~1,1%
set new_seq1=T
if /i %seq2%==T set new_seq1=H
set cpu_bet=%new_seq1%%seq1%%seq2%
echo.&echo Hmm... My bet will be %cpu_bet%. We'll see who's lucky...
:succesivetossing
set toses=&set cnt=0
echo.
<nul set /p "dummy=Tosses: "
:tossloop
call :tossgen
<nul set /p dummy=%toss%
ping -n 2 localhost >nul
set /a newline=%cnt%%%60
if %newline%==59 (
echo.
<nul set /p "dummy=. "
)
if "%toses:~-3,3%"=="%cpu_bet%" goto iwin
if "%toses:~-3,3%"=="%you_bet%" goto uwin
set /a cnt+=1&goto tossloop
:tossgen
set /a rand=%random%%%2
set toss=T
if %rand%==0 set toss=H
set toses=%toses%%toss%
goto :EOF
:iwin
set /a cpu+=1&set newgame=
echo.&echo.
echo I Win^^! Better Luck Next Time...
echo.
set /p "newgame=[Type Y if U Wanna Beat Me, or Else, Exit...] "
if /i "!newgame!"=="Y" goto :main
exit
:uwin
set /a you+=1&set newgame=
echo.&echo.
echo Argh, You Win^^! ...But One Time I'll Beat You.
echo.
set /p "newgame=[Type Y for Another Game, or Else, Exit...] "
if /i "!newgame!"=="Y" goto :main
exit
:validate
echo "!you_bet!"|findstr /r /c:"^\"[hHtT][hHtT][hHtT]\"$">nul || (
echo [Invalid Input...]&echo.&goto %1
)
if /i "!you_bet!"=="%cpu_bet%" (echo [Bet something different...]&echo.&goto %1)
for %%i in ("t=T" "h=H") do set "you_bet=!you_bet:%%~i!"
goto :EOF
```

{{out}} Note: The outputs of tosses are 'delayed' just to make the game a little more dramatic.

```
Penney's Game
Batch File Implementation
--------------------------------------------------------
CPU's Score: 0 Your Score: 0
Heads I start, Tails you start.... Heads!
I will bet first. So, my bet sequence will be THH.
What will be your bet sequence? tTh
So, you're feeling lucky on TTH. We'll see...
Tosses: HHTHTHH
I Win! Better Luck Next Time...
[Type Y if U Wanna Beat Me, or Else, Exit...] y
--------------------------------------------------------
CPU's Score: 1 Your Score: 0
Heads I start, Tails you start.... Tails!
Ok. You will bet first.
What will be your bet sequence? tHt
Hmm... My bet will be TTH. We'll see who's lucky...
Tosses: HTTH
I Win! Better Luck Next Time...
[Type Y if U Wanna Beat Me, or Else, Exit...]
```

## BBC BASIC

```
penney
PRINT "*** Penney's Game ***"
REPEAT
PRINT ' "Heads you pick first, tails I pick first."
PRINT "And it is... ";
WAIT 100
ht% = RND(0 - TIME) AND 1
IF ht% THEN
PRINT "heads!"
PROC_player_chooses(player$)
computer$ = FN_optimal(player$)
PRINT "I choose "; computer$; "."
ELSE
PRINT "tails!"
computer$ = FN_random
PRINT "I choose "; computer$; "."
PROC_player_chooses(player$)
ENDIF
PRINT "Starting the game..." ' SPC 5;
sequence$ = ""
winner% = FALSE
REPEAT
WAIT 100
roll% = RND AND 1
IF roll% THEN
sequence$ += "H"
PRINT "H ";
ELSE
PRINT "T ";
sequence$ += "T"
ENDIF
IF RIGHT$(sequence$, 3) = computer$ THEN
PRINT ' "I won!"
winner% = TRUE
ELSE
IF RIGHT$(sequence$, 3) = player$ THEN
PRINT ' "Congratulations! You won."
winner% = TRUE
ENDIF
ENDIF
UNTIL winner%
REPEAT
valid% = FALSE
INPUT "Another game? (Y/N) " another$
IF INSTR("YN", another$) THEN valid% = TRUE
UNTIL valid%
UNTIL another$ = "N"
PRINT "Thank you for playing!"
END
:
DEF PROC_player_chooses(RETURN sequence$)
LOCAL choice$, valid%, i%
REPEAT
valid% = TRUE
PRINT "Enter a sequence of three choices, each of them either H or T:"
INPUT "> " sequence$
IF LEN sequence$ <> 3 THEN valid% = FALSE
IF valid% THEN
FOR i% = 1 TO 3
choice$ = MID$(sequence$, i%, 1)
IF choice$ <> "H" AND choice$ <> "T" THEN valid% = FALSE
NEXT
ENDIF
UNTIL valid%
ENDPROC
:
DEF FN_random
LOCAL sequence$, choice%, i%
sequence$ = ""
FOR i% = 1 TO 3
choice% = RND AND 1
IF choice% THEN sequence$ += "H" ELSE sequence$ += "T"
NEXT
= sequence$
:
DEF FN_optimal(sequence$)
IF MID$(sequence$, 2, 1) = "H" THEN
= "T" + LEFT$(sequence$, 2)
ELSE
= "H" + LEFT$(sequence$, 2)
ENDIF
```

{{out}}

```
*** Penney's Game ***
Heads you pick first, tails I pick first.
And it is... heads!
Enter a sequence of three choices, each of them either H or T:
> HTT
I choose HHT.
Starting the game...
H H H H H T
I won!
Another game? (Y/N) Y
Heads you pick first, tails I pick first.
And it is... tails!
I choose HTH.
Enter a sequence of three choices, each of them either H or T:
> HHT
Starting the game...
T T H H H H T
Congratulations! You won.
Another game? (Y/N) N
Thank you for playing!
```

## C

This solution stores the sequences in bit-packed integers. With minor adjustments, this can be extended to allow larger sequence lengths beyond the required 3. However, the ai's algorithm for the perfect choice would need to be altered. More robust methods of input could be chosen, as scanf is generally fairly unsafe. A safer alternative would be to use something like fgets, and parse the input string ourselves.

#include <stdio.h> #include <stdlib.h> #include <time.h> #define SEQLEN 3 int getseq(char *s) { int r = 0; int i = 1 << (SEQLEN - 1); while (*s && i) { switch (*s++) { case 'H': case 'h': r |= i; break; case 'T': case 't': /* 0 indicates tails, this is 0, so do nothing */ break; default: return -1; } i >>= 1; } return r; } void printseq(int seq) { int i; for (i = SEQLEN - 1; i >= 0; --i) printf("%c", seq & (1 << i) ? 'h' : 't'); } int getuser(void) { int user; char s[SEQLEN + 1]; printf("Enter your sequence of %d (h/t): ", SEQLEN); while (1) { /* This needs to be manually changed if SEQLEN is changed */ if (scanf("%3s", s) != 1) exit(1); if ((user = getseq(s)) != -1) return user; printf("Please enter only h/t characters: "); } } int getai(int user) { int ai; printf("Computers sequence of %d is: ", SEQLEN); /* The ai's perfect choice will only be perfect for SEQLEN == 3 */ if (user == -1) ai = rand() & (1 << SEQLEN) - 1; else ai = (user >> 1) | ((~user << 1) & (1 << SEQLEN - 1)); printseq(ai); printf("\n"); return ai; } int rungame(int user, int ai) { /* Generate first SEQLEN flips. We only need to store the last SEQLEN * tosses at any one time. */ int last3 = rand() & (1 << SEQLEN) - 1; printf("Tossed sequence: "); printseq(last3); while (1) { if (user == last3) { printf("\nUser wins!\n"); return 1; } if (ai == last3) { printf("\nAi wins!\n"); return 0; } last3 = ((last3 << 1) & (1 << SEQLEN) - 2) | (rand() & 1); printf("%c", last3 & 1 ? 'h' : 't'); } } int main(void) { srand(time(NULL)); int playerwins = 0; int totalgames = 0; /* Just use ctrl-c for exit */ while (1) { int user = -1; int ai = -1; printf("\n"); if (rand() & 1) { ai = getai(user); user = getuser(); } else { user = getuser(); ai = getai(user); } playerwins += rungame(user, ai); totalgames++; printf("You have won %d out of %d games\n", playerwins, totalgames); printf(" ### =========================== \n"); } return 0; }

{{out}}

```
Enter your sequence of 3 (h/t): tth
Computers sequence of 3 is: htt
Tossed sequence: ttth
User wins!
You have won 1 out of 1 games
### ===========================
Enter your sequence of 3 (h/t): tth
Computers sequence of 3 is: htt
Tossed sequence: thhhthhhthhhtt
Ai wins!
You have won 1 out of 2 games
### ===========================
```

## C++

#include <time.h> #include <iostream> #include <string> using namespace std; class penney { public: penney() { pW = cW = 0; } void gameLoop() { string a; while( true ) { playerChoice = computerChoice = ""; if( rand() % 2 ) { computer(); player(); } else { player(); computer(); } play(); cout << "[Y] to play again "; cin >> a; if( a[0] != 'Y' && a[0] != 'y' ) { cout << "Computer won " << cW << " times." << endl << "Player won " << pW << " times."; break; } cout << endl << endl; } } private: void computer() { if( playerChoice.length() == 0 ) { for( int x = 0; x < 3; x++ ) computerChoice.append( ( rand() % 2 ) ? "H" : "T", 1 ); } else { computerChoice.append( playerChoice[1] == 'T' ? "H" : "T", 1 ); computerChoice += playerChoice.substr( 0, 2 ); } cout << "Computer's sequence of three is: " << computerChoice << endl; } void player() { cout << "Enter your sequence of three (H/T) "; cin >> playerChoice; } void play() { sequence = ""; while( true ) { sequence.append( ( rand() % 2 ) ? "H" : "T", 1 ); if( sequence.find( playerChoice ) != sequence.npos ) { showWinner( 1 ); break; } else if( sequence.find( computerChoice ) != sequence.npos ) { showWinner( 0 ); break; } } } void showWinner( int i ) { string s; if( i ) { s = "Player wins!"; pW++; } else { s = "Computer wins!"; cW++; } cout << "Tossed sequence: " << sequence << endl << s << endl << endl; } string playerChoice, computerChoice, sequence; int pW, cW; }; int main( int argc, char* argv[] ) { srand( static_cast<unsigned>( time( NULL ) ) ); penney game; game.gameLoop(); return 0; }

{{out}}

```
Computer's sequence of three is: HHH
Enter your sequence of three (H/T) THH
Tossed sequence: TTHTTTTTTTTTTTHTHTTTHTTHTTHH
Player wins!
[Y] to play again y
Enter your sequence of three (H/T) HTH
Computer's sequence of three is: HHT
Tossed sequence: THHT
Computer wins!
[Y] to play again
```

## C#

{{works with|C sharp|7}}

using static System.Console; using static System.Threading.Thread; using System; public static class PenneysGame { const int pause = 500; const int N = 3; static Random rng = new Random(); static int Toss() => rng.Next(2); static string AsString(this int sequence) { string s = ""; for (int b = 0b100; b > 0; b >>= 1) { s += (sequence & b) > 0 ? 'T' : 'H'; } return s; } static int UserInput() { while (true) { switch (ReadKey().Key) { case ConsoleKey.Escape: return -1; case ConsoleKey.H: return 0; case ConsoleKey.T: return 1; } Console.Write('\b'); } } public static void Main2() { int yourScore = 0, myScore = 0; while (true) { WriteLine($"Your score: {yourScore}, My score: {myScore}"); WriteLine("Determining who goes first..."); Sleep(pause); bool youStart = Toss() == 1; WriteLine(youStart ? "You go first." : "I go first."); int yourSequence = 0, mySequence = 0; if (youStart) { WriteLine("Choose your sequence of (H)eads and (T)ails (or press Esc to exit)"); int userChoice; for (int i = 0; i < N; i++) { if ((userChoice = UserInput()) < 0) return; yourSequence = (yourSequence << 1) + userChoice; } mySequence = ((~yourSequence << 1) & 0b100) | (yourSequence >> 1); } else { for (int i = 0; i < N; i++) { mySequence = (mySequence << 1) + Toss(); } WriteLine("I chose " + mySequence.AsString()); do { WriteLine("Choose your sequence of (H)eads and (T)ails (or press Esc to exit)"); int choice; yourSequence = 0; for (int i = 0; i < N; i++) { if ((choice = UserInput()) < 0) return; yourSequence = (yourSequence << 1) + choice; } if (yourSequence == mySequence) { WriteLine(); WriteLine("You cannot choose the same sequence."); } } while (yourSequence == mySequence); } WriteLine(); WriteLine($"Your sequence: {yourSequence.AsString()}, My sequence: {mySequence.AsString()}"); WriteLine("Tossing..."); int sequence = 0; for (int i = 0; i < N; i++) { Sleep(pause); int toss = Toss(); sequence = (sequence << 1) + toss; Write(toss > 0 ? 'T' : 'H'); } while (true) { if (sequence == yourSequence) { WriteLine(); WriteLine("You win!"); yourScore++; break; } else if (sequence == mySequence) { WriteLine(); WriteLine("I win!"); myScore++; break; } Sleep(pause); int toss = Toss(); sequence = ((sequence << 1) + toss) & 0b111; Write(toss > 0 ? 'T' : 'H'); } WriteLine("Press a key."); ReadKey(); Clear(); } } }

{{out}}

Your score: 0, My score: 0 Determining who goes first... I go first. I chose HHH Choose your sequence of (H)eads and (T)ails (or press Esc to exit) thh Your sequence: THH, My sequence: HHH Tossing... HTHTHTHTTHH You win! Press a key. Your score: 2, My score: 0 Determining who goes first... You go first. Choose your sequence of (H)eads and (T)ails (or press Esc to exit) thh Your sequence: THH, My sequence: TTH Tossing... HTTTTH I win! Press a key. ``` ## Clojure ```clojure (ns penney.core (:gen-class)) (def heads \H) (def tails \T) (defn flip-coin [] (let [flip (rand-int 2)] (if (= flip 0) heads tails))) (defn turn [coin] (if (= coin heads) tails heads)) (defn first-index [combo coll] (some #(if (= (second %) combo) (first %)) coll)) (defn find-winner [h c] (if (< h c) (do (println "YOU WIN!\n") :human) (do (println "COMPUTER WINS!\n") :computer))) (defn flip-off [human comp] (let [flips (repeatedly flip-coin) idx-flips (map-indexed vector (partition 3 1 flips)) h (first-index (seq human) idx-flips) c (first-index (seq comp) idx-flips)] (println (format "Tosses: %s" (apply str (take (+ 3 (min h c)) flips)))) (find-winner h c))) (defn valid? [combo] (if (empty? combo) true (and (= 3 (count combo)) (every? #(or (= heads %) (= tails %)) combo)))) (defn ask-move [] (println "What sequence of 3 Heads/Tails do you choose?") (let [input (clojure.string/upper-case (read-line))] (if-not (valid? input) (recur) input))) (defn optimize-against [combo] (let [mid (nth combo 1) comp (str (turn mid) (first combo) mid)] (println (format "Computer chooses %s: " comp)) comp)) (defn initial-move [game] (let [combo (apply str (repeatedly 3 flip-coin))] (println "--------------") (println (format "Current score | CPU: %s, You: %s" (:computer game) (:human game))) (if (= (:first-player game) tails) (do (println "Computer goes first and chooses: " combo) combo) (println "YOU get to go first.")))) (defn play-game [game] (let [c-move (initial-move game) h-move (ask-move)] (if-not (empty? h-move) (let [winner (flip-off h-move (if (nil? c-move) (optimize-against h-move) c-move))] (recur (assoc game winner (inc (winner game)) :first-player (flip-coin)))) (println "Thanks for playing!")))) (defn -main [& args] (println "Penney's Game.") (play-game {:first-player (flip-coin) :human 0, :computer 0})) ``` {{out}} ```txt Penney's Game. -------------- Current score | CPU: 0, You: 0 Computer goes first and chooses: THT What sequence of 3 Heads/Tails do you choose? tth Tosses: TTH YOU WIN! -------------- Current score | CPU: 0, You: 1 YOU get to go first. What sequence of 3 Heads/Tails do you choose? tht Computer chooses TTH: Tosses: HHHTTH COMPUTER WINS! -------------- Current score | CPU: 1, You: 1 YOU get to go first. What sequence of 3 Heads/Tails do you choose? Thanks for playing! ``` ## D {{trans|Python}} ```d void main() { import std.stdio, std.random, std.algorithm, std.string, std.conv, std.range, core.thread; immutable first = uniform(0, 2) == 0; string you, me; if (first) { me = 3.iota.map!(_ => "HT"[uniform(0, $)]).text; writefln("I choose first and will win on first seeing %s in the list of tosses", me); while (you.length != 3 || you.any!(c => !c.among('H', 'T')) || you == me) { "What sequence of three Heads/Tails will you win with: ".write; you = readln.strip; } } else { while (you.length != 3 || you.any!(c => !c.among('H', 'T'))) { "After you: What sequence of three Heads/Tails will you win with: ".write; you = readln.strip; } me = (you[1] == 'T' ? 'H' : 'T') ~ you[0 .. 2]; writefln("I win on first seeing %s in the list of tosses", me); } "Rolling:\n ".write; string rolled; while (true) { rolled ~= "HT"[uniform(0, $)]; rolled.back.write; if (rolled.endsWith(you)) return "\n You win!".writeln; if (rolled.endsWith(me)) return "\n I win!".writeln; Thread.sleep(1.seconds); } } ``` The output is the same as the Python entry. ## Elixir {{trans|Ruby}} ```elixir defmodule Penney do @toss [:Heads, :Tails] def game(score \\ {0,0}) def game({iwin, ywin}=score) do IO.puts "Penney game score I : #{iwin}, You : #{ywin}" [i, you] = @toss coin = Enum.random(@toss) IO.puts "#{i} I start, #{you} you start ..... #{coin}" {myC, yC} = setup(coin) seq = for _ <- 1..3, do: Enum.random(@toss) IO.write Enum.join(seq, " ") {winner, score} = loop(seq, myC, yC, score) IO.puts "\n #{winner} win!\n" game(score) end defp setup(:Heads) do myC = Enum.shuffle(@toss) ++ [Enum.random(@toss)] joined = Enum.join(myC, " ") IO.puts "I chose : #{joined}" {myC, yourChoice} end defp setup(:Tails) do yC = yourChoice myC = (@toss -- [Enum.at(yC,1)]) ++ Enum.take(yC,2) joined = Enum.join(myC, " ") IO.puts "I chose : #{joined}" {myC, yC} end defp yourChoice do IO.write "Enter your choice (H/T) " choice = read([]) IO.puts "You chose: #{Enum.join(choice, " ")}" choice end defp read([_,_,_]=choice), do: choice defp read(choice) do case IO.getn("") |> String.upcase do "H" -> read(choice ++ [:Heads]) "T" -> read(choice ++ [:Tails]) _ -> read(choice) end end defp loop(myC, myC, _, {iwin, ywin}), do: {"I", {iwin+1, ywin}} defp loop(yC, _, yC, {iwin, ywin}), do: {"You", {iwin, ywin+1}} defp loop(seq, myC, yC, score) do append = Enum.random(@toss) IO.write " #{append}" loop(tl(seq)++[append], myC, yC, score) end end Penney.game ``` {{out}} ```txt Penney game score I : 0, You : 0 Heads I start, Tails you start ..... Heads I chose : Tails Heads Heads Enter your choice (H/T) TTH You chose: Tails Tails Heads Heads Heads Tails Tails Tails Tails Heads You win! Penney game score I : 0, You : 1 Heads I start, Tails you start ..... Tails Enter your choice (H/T) THT You chose: Tails Heads Tails I chose : Tails Tails Heads Tails Heads Heads Heads Tails Tails Heads I win! Penney game score I : 1, You : 1 Heads I start, Tails you start ..... Tails Enter your choice (H/T) ``` ## Factor ```factor USING: arrays ascii io kernel math prettyprint random sequences strings ; IN: rosetta-code.penneys-game ! Generate a random boolean. : t|f ( -- t/f ) 1 random-bits 0 = ; ! Checks whether the sequence chosen by the human is valid. : valid-input? ( seq -- ? ) [ [ CHAR: H = ] [ CHAR: T = ] bi or ] filter length 3 = ; ! Prompt the human player for a sequence. : input-seq ( -- seq ) "Please input a 3-long sequence of H or T (heads or tails)." print "Example: HTH" print "> " write readln >upper >array ; ! Get the human player's input sequence with error checking. : get-input ( -- seq ) t [ drop input-seq dup valid-input? not ] loop ; ! Add a random coin flip to a vector. : flip-coin ( vector -- vector' ) t|f CHAR: H CHAR: T ? over push ; ! Generate a random 3-long sequence of coin flips. : rand-seq ( -- seq ) V{ } clone 3 [ flip-coin ] times ; ! Generate the optimal sequence response to a given sequence. : optimal ( seq1 -- seq2 ) [ second dup CHAR: H = [ CHAR: T ] [ CHAR: H ] if ] [ first ] [ second ] tri 3array nip dup "The computer chose " write >string write "." print ; ! Choose a random sequence for the computer and report what ! was chosen. : computer-first ( -- seq ) "The computer picks a sequence first and chooses " write rand-seq dup >string write "." print >array ; ! The human is prompted to choose any sequence with no ! restrictions. : human-first ( -- seq ) "You get to go first." print get-input ; ! Forbid the player from choosing the same sequence as the ! computer. : human-second ( cseq -- cseq hseq ) get-input [ 2dup = not ] [ drop "You may not choose the same sequence as the computer." print get-input ] until ; ! Display a message introducing the game. : welcome ( -- ) "Welcome to Penney's Game. The computer or the player" print "will be randomly selected to choose a sequence of" print "three coin tosses. The sequence will be shown to the" print "opponent, and then he will choose a sequence." print nl "Then, a coin will be flipped until the sequence" print "matches the last three coin flips, and a winner" print "announced." print nl ; ! Check for human victory. : human-won? ( cseq hseq coin-flips -- ? ) 3 tail* >array = nip ; ! Check for computer victory. : computer-won? ( cseq hseq coin-flips -- ? ) 3 tail* >array pick = 2nip ; ! Flip a coin until a victory is detected. Then, inform the ! player who won. : flip-coins ( cseq hseq -- ) "Flipping coins..." print rand-seq [ 3dup [ human-won? ] [ computer-won? ] 3bi or ] [ flip-coin ] until dup >string print human-won? [ "You won!" print ] [ "The computer won." print ] if ; ! Randomly choose a player to choose their sequence first. ! Then play a full round of Penney's Game. : start-game ( -- ) welcome t|f [ human-first dup optimal swap ] [ computer-first human-second ] if flip-coins ; start-game ``` {{out}} ```txt Welcome to Penney's Game. The computer or the player will be randomly selected to choose a sequence of three coin tosses. The sequence will be shown to the opponent, and then he will choose a sequence. Then, a coin will be flipped until the sequence matches the last three coin flips, and a winner announced. You get to go first. Please input a 3-long sequence of H or T (heads or tails). Example: HTH > car Please input a 3-long sequence of H or T (heads or tails). Example: HTH > htht Please input a 3-long sequence of H or T (heads or tails). Example: HTH > tth The computer chose HTT. Flipping coins... THHTHTHTHHTHHTHHTT The computer won. Welcome to Penney's Game. The computer or the player will be randomly selected to choose a sequence of three coin tosses. The sequence will be shown to the opponent, and then he will choose a sequence. Then, a coin will be flipped until the sequence matches the last three coin flips, and a winner announced. The computer picks a sequence first and chooses HHH. Please input a 3-long sequence of H or T (heads or tails). Example: HTH > hhh You may not choose the same sequence as the computer. Please input a 3-long sequence of H or T (heads or tails). Example: HTH > hht Flipping coins... HHH The computer won. ``` ## Go ```Go package main import "fmt" import "math/rand" func main(){ var a1,a2,a3,y,match,j,k int var inp string y=1 for y==1{ fmt.Println("Enter your sequence:") fmt.Scanln(&inp) var Ai [3] int var user [3] int for j=0;j<3;j++{ if(inp[j]==104){ user[j]=1 }else{ user[j]=0 } } for k=0;k<3;k++{ Ai[k]=rand.Intn(2) } for user[0]==Ai[0]&&user[1]==Ai[1]&&user[2]==Ai[2]{ for k=0;k<3;k++{ Ai[k]=rand.Intn(2) } } fmt.Println("You gave the sequence:") printht(user) fmt.Println() fmt.Println("The computer generated sequence is:") printht(Ai) fmt.Println() a1=rand.Intn(2) a2=rand.Intn(2) a3=rand.Intn(2) fmt.Print("The generated sequence is:") printh(a1) printh(a2) printh(a3) match=0 for match==0{ if(matches(user,a1,a2,a3)==1){ fmt.Println() fmt.Println("You have won!!!") match=1 }else if(matches(Ai,a1,a2,a3)==1){ fmt.Println() fmt.Println("You lost!! Computer wins") match=1 }else{ a1=a2 a2=a3 a3=rand.Intn(2) printh(a3) } } fmt.Println("Do you want to continue(0/1):") fmt.Scanln(&y) } } func printht(a [3] int) int{ var i int for i=0;i<3;i++{ if(a[i]==1){ fmt.Print("h") }else{ fmt.Print("t") } } return 1 } func printh(a int) int{ if(a==1){ fmt.Print("h") }else{ fmt.Print("t") } return 1 } func matches(a [3] int,p int,q int,r int) int{ if(a[0]==p&&a[1]==q&&a[2]==r){ return 1 }else{ return 0 } } ``` Output: ```txt Enter your sequence: tht You gave the sequence: tht The computer generated sequence is: hhh The generated sequence is:hhtht You have won!!! Do you want to continue(0/1): ``` ## Haskell ```Haskell import qualified Data.List as L import System.IO import System.Random data CoinToss = H | T deriving (Read, Show, Eq) parseToss :: String -> [CoinToss] parseToss [] = [] parseToss (s:sx) | s == 'h' || s == 'H' = H : parseToss sx | s == 't' || s == 'T' = T : parseToss sx | otherwise = parseToss sx notToss :: CoinToss -> CoinToss notToss H = T notToss T = H instance Random CoinToss where random g = let (b, gb) = random g in (if b then H else T, gb) randomR = undefined prompt :: (Read a) => String -> String -> (String -> Maybe a) -> IO a prompt msg err parse = do putStrLn msg line <- getLine let ans = parse line case ans of Nothing -> do putStrLn err prompt msg err parse Just ansB -> return ansB showCat :: (Show a) => [a] -> String showCat = concatMap show data Winner = Player | CPU -- This may never terminate. runToss :: (RandomGen g) => [CoinToss] -> [CoinToss] -> g -> ([CoinToss], Winner) runToss player cpu gen = let stream = randoms gen run ss@(s:sx) | L.isPrefixOf player ss = player | L.isPrefixOf cpu ss = cpu | otherwise = s : run sx winner = run stream in if L.isSuffixOf player winner then (winner, Player) else (winner, CPU) game :: (RandomGen g, Num a, Show a) => Bool -> a -> a -> g -> IO () game cpuTurn playerScore cpuScore gen = do putStrLn $ "\nThe current score is CPU: " ++ show cpuScore ++ ", You: " ++ show playerScore let (genA, genB) = split gen promptPlayer check = prompt "Pick 3 coin sides: " "Invalid input." $ \s -> let tosses = parseToss s in if check tosses then Just tosses else Nothing promptCpu x = putStrLn $ "I have chosen: " ++ showCat x (tosses, winner) <- if cpuTurn then do let cpuChoice = take 3 $ randoms gen promptCpu cpuChoice playerChoice <- promptPlayer $ \n -> n /= cpuChoice && 3 == length n return $ runToss playerChoice cpuChoice genA else do playerChoice <- promptPlayer $ \n -> 3 == length n let cpuChoice = case playerChoice of [a,b,_] -> [notToss b, a, b] promptCpu cpuChoice return $ runToss playerChoice cpuChoice genA putStrLn $ "The sequence tossed was: " ++ showCat tosses case winner of Player -> do putStrLn "You win!" game (not cpuTurn) (playerScore + 1) cpuScore genB CPU -> do putStrLn "I win!" game (not cpuTurn) playerScore (cpuScore + 1) genB main :: IO () main = do hSetBuffering stdin LineBuffering stdgen <- getStdGen let (cpuFirst, genA) = random stdgen game cpuFirst 0 0 genA ``` {{out}} ```txt The current score is CPU: 0, You: 0 Pick 3 coin sides: HTH I have chosen: HHT The sequence tossed was: TTTTTTHHT I win! The current score is CPU: 1, You: 0 I have chosen: TTT Pick 3 coin sides: HTT The sequence tossed was: HTT You win! The current score is CPU: 1, You: 1 Pick 3 coin sides: ``` ## J '''Solution:''' ```J require 'format/printf numeric' randomize '' NB. randomize seed for new session Vals=: 'HT' NB. valid values input=: 1!:1@<&1: NB. get input from user prompt=: input@echo NB. prompt user for input checkInput=: 'Choose 3 H/Ts' assert (Vals e.~ ]) , 3 = # getUserSeq=: (] [ checkInput)@toupper@prompt choose1st=: Vals {~ 3 ?@$ 2: NB. computer chooses 1st choose2nd=: (0 1 1=1 0 1{])&.(Vals&i.) NB. computer chooses 2nd playPenney=: verb define if. ?2 do. NB. randomize first chooser Comp=. choose1st '' 'Computer chose %s' printf) { var userSeq: String var compSeq: String val r = rand.nextInt(2) if (r == 0) { println("You go first") userSeq = getUserSequence() println() compSeq = getComputerSequence(userSeq) } else { println("Computer goes first") compSeq = getComputerSequence() println() userSeq = getUserSequence() } println() val coins = StringBuilder() while (true) { val coin = if (rand.nextInt(2) == 0) 'H' else 'T' coins.append(coin) println("Coins flipped: $coins") val len = coins.length if (len >= 3) { val seq = coins.substring(len - 3, len) if (seq == userSeq) { println("\nYou win!") return } else if (seq == compSeq) { println("\nComputer wins!") return } } Thread.sleep(2000) // wait two seconds for next flip } } ``` Sample game where computer goes first: ```txt Computer goes first Computer's sequence: HTT A sequence of three H or T should be entered Enter your sequence: HHT Coins flipped: H Coins flipped: HH Coins flipped: HHT You win! ``` Sample game where user goes first: ```txt You go first A sequence of three H or T should be entered Enter your sequence: HTH Computer's sequence: HHT Coins flipped: T Coins flipped: TT Coins flipped: TTT Coins flipped: TTTT Coins flipped: TTTTH Coins flipped: TTTTHT Coins flipped: TTTTHTH You win! ``` ## Lua ```lua function penny_game() local player, computer = "", "" function player_choose() io.write( "Enter your sequence of three H and/or T: " ) local t = io.read():upper() if #t > 3 then t = t:sub( 1, 3 ) elseif #t < 3 then return "" end for i = 1, 3 do c = t:sub( i, i ) if c ~= "T" and c ~= "H" then print( "Just H's and T's!" ) return "" end end return t end function computer_choose() local t = "" if #player > 0 then if player:sub( 2, 2 ) == "T" then t = "H" else t = "T"; end t = t .. player:sub( 1, 2 ) else for i = 1, 3 do if math.random( 2 ) == 1 then t = t .. "H" else t = t .. "T" end end end return t end if math.random( 2 ) == 1 then computer = computer_choose() io.write( "My sequence is: " .. computer .. "\n" ) while( true ) do player = player_choose() if player:len() == 3 then break end end else while( true ) do player = player_choose() if player:len() == 3 then break end end computer = computer_choose() io.write( "My sequence is: " .. computer .. "\n" ) end local coin, i = "", 1 while( true ) do if math.random( 2 ) == 1 then coin = coin .. "T" io.write( "T" ) else coin = coin .. "H" io.write( "H" ) end if #coin > 2 then local seq = coin:sub( i, i + 2 ) i = i + 1 if seq == player then print( "\nPlayer WINS!!!" ) return 1 elseif seq == computer then print( "\nComputer WINS!!!" ) return -1 end end end end math.randomseed( os.time() ) local cpu, user = 0, 0 repeat r = penny_game() if r > 0 then user = user + 1 else cpu = cpu + 1 end print( "Player: " .. user .. " CPU: " .. cpu ) io.write( "Play again (Y/N)? " ) r = io.read() until( r == "N" or r == "n" ) ``` {{out}} ```txt >lua -e "io.stdout:setvbuf 'no'" "penny.lua" My sequence is: TTH Enter your sequence of three H and/or T: HHT TTTTH Computer WINS!!! Player: 0 CPU: 1 Play again (Y/N)? y Enter your sequence of three H and/or T: HTH My sequence is: HHT THTTHTH Player WINS!!! Player: 1 CPU: 1 Play again (Y/N)? y My sequence is: HHH Enter your sequence of three H and/or T: TTH HTTHHTH Player WINS!!! Player: 2 CPU: 1 Play again (Y/N)? n >Exit code: 0 ``` ## MiniScript ```MiniScript randomTorH = function() if rnd < 0.5 then return "T" else return "H" end function if rnd < 0.5 then playerSeq = input("Input your sequence (e.g. HTH): ").upper if playerSeq[1] == "T" then compSeq = "H" else compSeq = "T" compSeq = compSeq + playerSeq[:2] print "I choose: " + compSeq else compSeq = randomTorH + randomTorH + randomTorH print "I choose: " + compSeq playerSeq = input("Input your sequence (e.g. HTH): ").upper end if print "Here we go..." seq = "" while true flip = randomTorH print flip seq = seq + flip if seq[-3:] == playerSeq then print "You win!" break else if seq[-3:] == compSeq then print "I win!" break end if wait end while ``` {{out}} ```txt Input your sequence (e.g. HTH): HTH I choose: HHT Here we go... T H T H You win! ``` ```txt I choose: TTH Input your sequence (e.g. HTH): THH Here we go... H T T T T H I win! ``` ## Pascal ```pascal PROGRAM Penney; TYPE CoinToss = (heads, tails); Sequence = array [1..3] of CoinToss; Player = record bet: Sequence; score: integer; end; VAR Human, Computer: Player; Rounds, Count: integer; Function TossCoin: CoinToss; { Returns heads or tails at random } Begin if random(2) = 1 then TossCoin := Heads else TossCoin := tails End; Procedure PutToss(toss: CoinToss); { Outputs heads or tails as a letter } Begin if toss = heads then write('H') else write('T') End; Function GetToss: CoinToss; { Reads H or T from the keyboard in either lettercase } var c: char; Begin { Keep reading characters until we get an appropriate letter } repeat read(c) until c in ['H', 'h', 'T', 't']; { Interpret the letter } if c in ['H', 'h'] then GetToss := heads else GetToss := tails End; Procedure ShowSequence(tosses: Sequence); { Outputs three coin tosses at once } Var i: integer; Begin for i := 1 to 3 do PutToss(tosses[i]) End; Procedure ReadSequence(var tosses: Sequence); { Accepts three coin tosses from the keyboard } Var i: integer; Begin { Get the 3 letters } for i := 1 to 3 do tosses[i] := GetToss; { Ignore the rest of the line } readln End; Function Optimum(opponent: Sequence): Sequence; { Generates the optimum sequence against an opponent } Begin case opponent[2] of heads: Optimum[1] := tails; tails: Optimum[1] := heads end; Optimum[2] := opponent[1]; Optimum[3] := opponent[2] End; Function RandomSequence: Sequence; { Generates three random coin tosses } Var i: integer; Begin for i := 1 to 3 do RandomSequence[i] := TossCoin End; Function Match(first, second: Sequence): Boolean; { Detects whether a sequence of tosses matches another } Var different: boolean; i: integer; Begin different := false; i := 1; while (i <= 3) and not different do begin if not (first[i] = second[i]) then different := true; i := i + 1 end; Match := not different End; Procedure PlayRound(var human, computer: Player); { Shows coin tosses and announces the winner } Var { We only ever need to store the 3 most recent tosses in memory. } tosses: Sequence; Begin { Start with the first three tosses } write('Tossing the coin: '); tosses := RandomSequence; ShowSequence(tosses); { Keep tossing the coin until there is a winner. } while not (Match(human.bet, tosses) or Match(computer.bet, tosses)) do begin tosses[1] := tosses[2]; tosses[2] := tosses[3]; tosses[3] := TossCoin; PutToss(tosses[3]) end; { Update the winner's score and announce the winner } writeln; writeln; if Match(human.bet, tosses) then begin writeln('Congratulations! You won this round.'); human.score := human.score + 1; writeln('Your new score is ', human.score, '.') end else begin writeln('Yay, I won this round!'); computer.score := computer.score + 1; writeln('My new score is ', computer.score, '.') end End; { Main Algorithm } BEGIN { Welcome the player } writeln('Welcome to Penney''s game!'); writeln; write('How many rounds would you like to play? '); readln(Rounds); writeln; writeln('Ok, let''s play ', Rounds, ' rounds.'); { Start the game } randomize; Human.score := 0; Computer.score := 0; for Count := 1 to Rounds do begin writeln; writeln('*** Round #', Count, ' ***'); writeln; { Choose someone randomly to pick the first sequence } if TossCoin = heads then begin write('I''ll pick first this time.'); Computer.bet := RandomSequence; write(' My sequence is '); ShowSequence(Computer.bet); writeln('.'); repeat write('What sequence do you want? '); ReadSequence(Human.bet); if Match(Human.bet, Computer.bet) then writeln('Hey, that''s my sequence! Think for yourself!') until not Match(Human.bet, Computer.bet); ShowSequence(Human.bet); writeln(', huh? Sounds ok to me.') end else begin write('You pick first this time. Enter 3 letters H or T: '); ReadSequence(Human.bet); Computer.bet := Optimum(Human.bet); write('Ok, so you picked '); ShowSequence(Human.bet); writeln; write('My sequence will be '); ShowSequence(Computer.bet); writeln end; { Then we can actually play the round } writeln('Let''s go!'); writeln; PlayRound(Human, Computer); writeln; writeln('Press ENTER to go on...'); readln end; { All the rounds are finished; time to decide who won } writeln; writeln('*** End Result ***'); writeln; if Human.score > Computer.score then writeln('Congratulations! You won!') else if Computer.score > Human.score then writeln('Hooray! I won') else writeln('Cool, we tied.'); writeln; writeln('Press ENTER to finish.'); readln END. ``` {{out}} ```txt Welcome to Penney's game! How many rounds would you like to play? 3 Ok, let's play 3 rounds. *** Round #1 *** I'll pick first this time. My sequence is TTH. What sequence do you want? H tt HTT, huh? Sounds ok to me. Let's go! Tossing the coin: HHHHTHHHHHHTHHHHTHHTHTHTT Congratulations! You won this round. Your new score is 1. Press ENTER to go on... *** Round #2 *** I'll pick first this time. My sequence is THT. What sequence do you want? tth TTH, huh? Sounds ok to me. Let's go! Tossing the coin: THT Yay, I won this round! My new score is 1. Press ENTER to go on... *** Round #3 *** You pick first this time. Enter 3 letters H or T: h t h Ok, so you picked HTH My sequence will be HHT Let's go! Tossing the coin: HHT Yay, I won this round! My new score is 2. Press ENTER to go on... *** End Result *** Hooray! I won Press ENTER to finish. ``` ## Perl ```perl #!usr/bin/perl use 5.020; use strict; use warnings; #Choose who goes first binaryRand() == 0 ? flipCoin(userFirst()) : flipCoin(compFirst()); #Return a randomly generated 1 or 0 sub binaryRand { return int(rand(2)); } #Converts 1's and 0's to H's and T's, respectively. sub convert { my $randNum = binaryRand(); if($randNum == 0) { return "T" } else { return "H"; } } #Prompts for and returns a user's sequence of 3 sub uSeq { print("Please enter a sequence of 3 of \"H\" and \"T\". EG: HHT\n>"); my $uString = ; while(1) { #Make it uppercase and validate input chomp($uString); $uString = uc $uString; #Check length and content (H's and T's only!) if(length $uString == 3 && (substr($uString, 0, 1) =~ /[HT]/ && substr($uString, 1, 1) =~ /[HT]/ && substr($uString, 2, 1) =~ /[HT]/)) { last; } else { print("Error, try again. \n"); print("Please enter a sequence of 3 of \"H\" and \"T\". EG: HHT\n"); $uString = ; } } return $uString; } #Returns an array with two elements: [0] user's seq, [1] random computer seq. sub compFirst { my $cSeq; #Randomly draw a sequence of 3 for(my $i = 0; $i < 3; $i++) { $cSeq = $cSeq . convert(); } print("The computer guesses first:\ncomp- $cSeq\n"); my $uSeq = uSeq(); print("user- $uSeq\n"); my @seqArr = ($uSeq, $cSeq); return @seqArr; } #Returns an array with two elements: [0] user's seq, [1] optimal computer seq. sub userFirst { print("The user quesses first:\n"); my $uSeq = uSeq(); my $cSeq; #Generate the optimal sequence based on $uSeq my $middle = substr($uSeq, 1, 1); $middle eq "H" ? $cSeq = "T" : $cSeq = "H"; $cSeq = $cSeq . substr($uSeq, 0, 2); print("user- $uSeq\ncomp- $cSeq\n"); my @seqArr = ($uSeq, $cSeq); return @seqArr; } #Flips a coin, checking both sequences against the contents of the given array sub flipCoin { my ($uSeq, $cSeq) = @_; my $coin; while(1) { $coin = $coin . convert(); if($coin =~ m/$uSeq/) { print("The sequence of tosses was: $coin\n"); say("The player wins! "); last; } elsif($coin =~ m/$cSeq/) { print("The sequence of tosses was: $coin\n"); say("The computer wins! "); last; } } } ``` {{out}} ```txt The computer guesses first: comp- HHH Please enter a sequence of 3 of "H" and "T". EG: HHT >thh user- THH The sequence of tosses was: HTTHTTHTHTHTTTHTTTHH The player wins! ### ========================================== The user quesses first: Please enter a sequence of 3 of "H" and "T". EG: HHT >hht user- HHT comp- HHH The sequence of tosses was: THHH The computer wins! ``` ## Perl 6 {{works with|Rakudo|2018.02}} ```perl6>enum Coin ; enum Boo ; enum Bozo «'Dude' 'Cha' 'Bzzt' 'Hey' 'Silly dilly' 'Say what!?' 'You numbskull'»; sub flipping { for 1..4 { print "-\b"; sleep .1; print "\\\b"; sleep .1; print "|\b"; sleep .1; print "/\b"; sleep .1; } } sub your-choice($p is copy) { loop (my @seq; @seq != 3; $p = "{Bozo.pick}! Please pick exactly 3: ") { @seq = prompt($p).uc.comb(/ H | T /).map: { when 'H' { Heads } when 'T' { Tails } } } @seq; } repeat until prompt("Wanna play again? ").lc ~~ /^n/ { my $mefirst = Coin.roll; print tc "$mefirst I start, {Coin(+!$mefirst).lc} you start, flipping...\n\t"; flipping; say my $flip = Coin.roll; my @yours; my @mine; if $flip == $mefirst { print "{Yay.pick}! I get to choose first, and I choose: "; sleep 2; say @mine = |Coin.roll(3); @yours = your-choice("Now you gotta choose: "); while @yours eqv @mine { say "{Bozo.pick}! We'd both win at the same time if you pick that!"; @yours = your-choice("Pick something different from me: "); } say "So, you'll win if we see: ", @yours; } else { @yours = your-choice("{Boo.pick}! First you choose: "); say "OK, you'll win if we see: ", @yours; print "In that case, I'll just randomly choose: "; sleep 2; say @mine = Coin(+!@yours[1]), |@yours[0,1]; } sub check($a,$b,$c) { given [$a,$b,$c] { when @mine { say "\n{Yay.pick}, I win, and you lose!"; Nil } when @yours { say "\n{Boo.pick}, you win, but I'll beat you next time!"; Nil } default { Coin.roll } } } sleep 1; say < OK! Ready? Right... So... Yo!>.pick; sleep .5; say ("Pay attention now!", "Watch closely!", "Let's do it...", "You feeling lucky?", "No way you gonna win this...", "Can I borrow that coin again?").pick; sleep 1; print "Here we go!\n\t"; for |Coin.roll(3), &check ...^ :!defined { flipping; print "$_ "; } } ``` {{out}} Note: the actual run displays a little coin-flipping animation, but that won't show up here: ```txt Heads I start, tails you start, flipping... Heads Yipee! I get to choose first, and I choose: Heads Heads Tails Now you gotta choose: tth So, you'll win if we see: Tails Tails Heads Yo! Can I borrow that coin again? Here we go! Tails Tails Tails Tails Tails Heads Argh, you win, but I'll beat you next time! Wanna play again? y Tails I start, heads you start, flipping... Tails Yes! I get to choose first, and I choose: Heads Tails Tails Now you gotta choose: H T T Dude! We'd both win at the same time if you pick that! Pick something different from me: heads tails tails Silly dilly! We'd both win at the same time if you pick that! Pick something different from me: h,h,h So, you'll win if we see: Heads Heads Heads OK! You feeling lucky? Here we go! Tails Tails Tails Heads Heads Heads Drat, you win, but I'll beat you next time! Wanna play again? y Heads I start, tails you start, flipping... Tails Shards! First you choose: tht OK, you'll win if we see: Tails Heads Tails In that case, I'll just randomly choose: Tails Tails Heads Right... Pay attention now! Here we go! Heads Tails Tails Heads Hah, I win, and you lose! Wanna play again? n ``` ## Phix {{trans|C}} Robert's robot's name is Robort. ```Phix function trio(integer pick) return substitute_all(sprintf("%03b",pick),"10","HT") end function function getuser(integer bot) integer user while 1 do user = 8 -- (a bit that clears after 3 shifts) printf(1,"Enter your sequence of 3 (H/T):"); while user>7 do integer c = upper(wait_key()) if c=#1B then abort(0) end if -- (Escape) if find(c,"HT") then puts(1,c) user = and_bits(user*2+(c='H'),0b111111) end if end while if user!=bot then exit end if printf(1,"\nYou may not pick the same as Robort!\n") end while printf(1,"\n") return user end function function getbot(int user) int bot = iff(user=-1?rand(8)-1 :4-and_bits(user,2)*2+floor(user/2)) printf(1,"Robort picks %s\n", {trio(bot)}) return bot end function function rungame(integer user, bot) /* We only need to store the last 3 tosses, as 0..7 */ int last3 = rand(8)-1 printf(1,"Rolling: %s",{trio(last3)}) while 1 do if user=last3 then printf(1,"\nUser wins!\n") return 1 elsif bot=last3 then printf(1,"\nRobort wins!\n") return 0 end if last3 = and_bits(last3,3)*2+(rand(2)=1) printf(1,"%c", iff(and_bits(last3,1) ? 'H' : 'T')) sleep(0.5) end while end function procedure main() integer playerwins = 0, totalgames = 0, robortwins = 0 /* Just use ctrl-c or Escape to exit */ while 1 do integer user = -1, bot = -1 printf(1,"\n") if rand(2)=1 then bot = getbot(-1) user = getuser(bot) else user = getuser(-1) bot = getbot(user) end if playerwins += rungame(user, bot) totalgames += 1 robortwins = totalgames-playerwins printf(1,"Robort:%d You:%d out of %d games\n", {robortwins, playerwins, totalgames}) printf(1," ### ============================ \n") end while end procedure main() ``` {{out}} ```txt Robort picks TTT Enter your sequence of 3 (H/T):TTT You may not pick the same as Robort! Enter your sequence of 3 (H/T):HHH Rolling: HTTT Robort wins! Robort:1 You:0 out of 1 games ### ============================ Enter your sequence of 3 (H/T):HTH Robort picks HHT Rolling: THTTTHHHHHHT Robort wins! Robort:2 You:0 out of 2 games ### ============================ Enter your sequence of 3 (H/T):TTH Robort picks HTT Rolling: THTT Robort wins! Robort:3 You:0 out of 3 games ### ============================ Enter your sequence of 3 (H/T):HTH Robort picks HHT Rolling: TTHHHHHHT Robort wins! Robort:4 You:0 out of 4 games ### ============================ Enter your sequence of 3 (H/T):HHT Robort picks THH Rolling: TTHH Robort wins! Robort:5 You:0 out of 5 games ### ============================ Enter your sequence of 3 (H/T):THH Robort picks TTH Rolling: THH User wins! Robort:5 You:1 out of 6 games ### ============================ ``` ## PicoLisp ```PicoLisp (seed (in "/dev/urandom" (rd 8))) (setq *S (list 0 0)) (de toss (N) (make (do N (link (if (rand T) "T" "H")) ) ) ) (de comp (A Lst) (or (for ((I . L) Lst (cddr L) (cdr L)) (T (fully = A L) I) ) T ) ) (de score NIL (prinl) (prinl "Total score:") (prinl "^Iuser: " (car *S)) (prinl "^Icomp: " (cadr *S)) ) (de play NIL (let (C (toss 3) Lst (toss (rand 5 12)) U) (prinl) (prin "Select toss: ") (setq U (in NIL (skip) (line))) (prinl "Comp toss: " C) (prinl "Toss: " Lst) (setq @ (comp U Lst) @@ (comp C Lst) ) (cond ((< @ @@) (prinl "User win.") (inc *S)) ((> @ @@) (prinl "Comp win.") (inc (cdr *S))) (T (prinl "Draw, lets play again.")) ) (score) ) ) (de go NIL (loop (play) (T (prog (prinl) (prin "Want play again? Y/N: ") (= "N" (uppc (in NIL (char)))) ) ) ) ) (go) ``` {{out}} ```txt Select toss: HTH Comp toss: THT Toss: HHTHTTHT User win. Total score: user: 1 comp: 0 Want play again? Y/N: y Select toss: HHH Comp toss: HTH Toss: THHHTTHTHHH User win. Total score: user: 2 comp: 0 Want play again? Y/N: y Select toss: TTT Comp toss: THH Toss: TTHTTHHHHTH Comp win. Total score: user: 2 comp: 1 Want play again? Y/N: n ``` =={{Header|Prolog}}== ```prolog play :- rand1(R), game(R). game(h) :- format('Your turn first!~n'), player_move(P), response(P,C), format('I am choosing '), maplist(writec, C), nl, rand3(R), maplist(writec,R), roll(P, C, R). game(t) :- rand3(C), format('I am choosing '), maplist(writec, C), nl, player_move(P), rand3(R), maplist(writec, R), roll(P, C, R). player_move([P1,P2,P3]) :- read_line_to_codes(user_input,Codes), maplist(char_code,[P1,P2,P3],Codes). roll(P, _, P) :- format('~nYou Win!~n'), !. roll(_, C, C) :- format('~nI Win!~n'), !. roll(P, C, [_,A,B]) :- rand1(R), coin_s(R,S), write(S), roll(P,C,[A,B,R]). response([A,B,_], [C,A,B]) :- opp(A,C). writec(A) :- coin_s(A,A1), write(A1). rand1(R) :- random(V), round(V,I), coin(I,R). rand3([R1,R2,R3]) :- rand1(R1), rand1(R2), rand1(R3). coin(0,h). coin(1,t). coin_s(h, 'H'). coin_s(t, 'T'). opp(h, t). opp(t, h). ``` Output: ```txt ?- play. I am choosing HTT |: tth HHTHHHHHHHHTHHHHTHTHTHTHTHHTT I Win! true. ?- play. Your turn first! |: hht I am choosing THH TTHTHH I Win! ``` =={{Header|Python}}== ```python from __future__ import print_function import random from time import sleep first = random.choice([True, False]) you = '' if first: me = ''.join(random.sample('HT'*3, 3)) print('I choose first and will win on first seeing {} in the list of tosses'.format(me)) while len(you) != 3 or any(ch not in 'HT' for ch in you) or you == me: you = input('What sequence of three Heads/Tails will you win with: ') else: while len(you) != 3 or any(ch not in 'HT' for ch in you): you = input('After you: What sequence of three Heads/Tails will you win with: ') me = ('H' if you[1] == 'T' else 'T') + you[:2] print('I win on first seeing {} in the list of tosses'.format(me)) print('Rolling:\n ', end='') rolled = '' while True: rolled += random.choice('HT') print(rolled[-1], end='') if rolled.endswith(you): print('\n You win!') break if rolled.endswith(me): print('\n I win!') break sleep(1) # For dramatic effect ``` {{out}} ```txt >>> After you: What sequence of three Heads/Tails will you win with: TTH I win on first seeing HTT in the list of tosses Rolling: THHTHHTT I win! >>> ### ============================= RESTART ============================= >>> I choose first and will win on first seeing HHT in the list of tosses What sequence of three Heads/Tails will you win with: THH Rolling: HTHTHTTTHTTTTTTHH You win! >>> ``` ## R ```rsplus # ### ========================================================= # Penney's Game Task from Rosetta Code Wiki # R implementation # ### ========================================================= penneysgame <- function() { #--------------------------------------------------------------- # Who goes first? #--------------------------------------------------------------- first <- sample(c("PC", "Human"), 1) #--------------------------------------------------------------- # Determine the sequences #--------------------------------------------------------------- if (first == "PC") { # PC goes first pc.seq <- sample(c("H", "T"), 3, replace = TRUE) cat(paste("\nI choose first and will win on first seeing", paste(pc.seq, collapse = ""), "in the list of tosses.\n\n")) human.seq <- readline("What sequence of three Heads/Tails will you win with: ") human.seq <- unlist(strsplit(human.seq, "")) } else if (first == "Human") { # Player goest first cat(paste("\nYou can choose your winning sequence first.\n\n")) human.seq <- readline("What sequence of three Heads/Tails will you win with: ") human.seq <- unlist(strsplit(human.seq, "")) # Split the string into characters pc.seq <- c(human.seq[2], human.seq[1:2]) # Append second element at the start pc.seq[1] <- ifelse(pc.seq[1] == "H", "T", "H") # Switch first element to get the optimal guess cat(paste("\nI win on first seeing", paste(pc.seq, collapse = ""), "in the list of tosses.\n")) } #--------------------------------------------------------------- # Start throwing the coin #--------------------------------------------------------------- cat("\nThrowing:\n") ran.seq <- NULL while(TRUE) { ran.seq <- c(ran.seq, sample(c("H", "T"), 1)) # Add a new coin throw to the vector of throws cat("\n", paste(ran.seq, sep = "", collapse = "")) # Print the sequence thrown so far if (length(ran.seq) >= 3 && all(tail(ran.seq, 3) == pc.seq)) { cat("\n\nI win!\n") break } if (length(ran.seq) >= 3 && all(tail(ran.seq, 3) == human.seq)) { cat("\n\nYou win!\n") break } Sys.sleep(0.5) # Pause for 0.5 seconds } } ``` {{out}} Human first. ```txt You can choose your winning sequence first. What sequence of three Heads/Tails will you win with: THH I win on first seeing TTH in the list of tosses. Throwing: T TT TTT TTTH I win! ``` PC first ```txt I choose first and will win on first seeing THH in the list of tosses. What sequence of three Heads/Tails will you win with: TTH Throwing: T TH THT THTT THTTH You win! ``` ## Racket This does what's required of it from the task... just don't input anything outside the alphabet "htHT" for the human move. ```racket #lang racket ;; Penney's Game. Tim Brown 2014-10-15 (define (flip . _) (match (random 2) (0 "H") (1 "T"))) (define (get-human-sequence) ; no sanity checking here! (display "choose your winning sequence of 3 H or T > ") (drop-right (drop (string-split (string-upcase (read-line)) "") 1) 1)) (define flips->string (curryr string-join ".")) (define (game-on p1 p2) (printf "~a chooses: ~a. ~a chooses: ~a~%" (car p1) (flips->string (cdr p1)) (car p2) (flips->string (cdr p2))) (match-define (list (list name.1 p1.1 p1.2 p1.3) (list name.2 p2.1 p2.2 p2.3)) (list p1 p2)) (let turn ((seq null)) (match seq [(list-rest (== p1.3) (== p1.2) (== p1.1) _) name.1] [(list-rest (== p2.3) (== p2.2) (== p2.1) _) name.2] [else (let* ((flp (flip)) (seq+ (cons flp else))) (printf "new-flip: ~a -> ~a~%" flp (flips->string (reverse seq+))) (turn seq+))]))) (define (play-game) (define-values (player-1 player-2) (match (flip) ["H" (printf "Human chooses first: ") (define p1 (cons 'Hom-Sap (get-human-sequence))) (values p1 (cons 'Computer (match p1 [(list _ f1 (and f2 (app (match-lambda ("H" "T") ("T" "H")) ¬f2)) _) (list ¬f2 f1 f2)])))] ["T" (printf "Computer chooses first. ") (define p1 (cons 'Computer (build-list 3 flip))) (printf "~a chooses: ~a~%" (car p1) (flips->string (cdr p1))) (values p1 (cons 'Hom-Sap (get-human-sequence)))])) (printf "~a wins!~%" (game-on player-1 player-2))) ``` {{out}} ===Homo Sapiens Plays First (and wins!)=== ```txt > (play-game) Human chooses first: choose your winning sequence of 3 H or T > hth Hom-Sap chooses: H.T.H. Computer chooses: H.H.T new-flip: H -> H new-flip: T -> H.T new-flip: H -> H.T.H Hom-Sap wins! ``` ===The Computer Plays First (and loses!)=== ```txt > (play-game) Computer chooses first. Computer chooses: T.T.T choose your winning sequence of 3 H or T > htt Computer chooses: T.T.T. Hom-Sap chooses: H.T.T new-flip: H -> H new-flip: H -> H.H new-flip: H -> H.H.H new-flip: T -> H.H.H.T new-flip: H -> H.H.H.T.H new-flip: T -> H.H.H.T.H.T new-flip: H -> H.H.H.T.H.T.H new-flip: T -> H.H.H.T.H.T.H.T new-flip: H -> H.H.H.T.H.T.H.T.H new-flip: T -> H.H.H.T.H.T.H.T.H.T new-flip: T -> H.H.H.T.H.T.H.T.H.T.T Hom-Sap wins! ``` (Nail-biting stuff!) ## REXX The REXX program keeps a running score (number of wins out of so many games played) as well as allowing the human to pick the number (length) of the coin toss sequence. A fair amount of code was added to ensure a valid response from the human player as well as give an informative error message. The human player is allowed to spell out the '''H''' or '''T''' (as '''heads''' or '''tails'''). A feature also added was to allow a seed for the '''random''' BIF to allow repeatability for a game. ```rexx /*REXX program plays/simulates Penney's Game, a two-player coin toss sequence game. */ __=copies('─',9) /*literal for eyecatching fence. */ signal on halt /*a clean way out if CLBF quits. */ parse arg # seed . /*obtain optional arguments from the CL*/ if #=='' | #=="," then #=3 /*Not specified? Then use the default.*/ if datatype(seed,'W') then call random ,,seed /*use seed for RANDOM #s repeatability.*/ wins=0; do games=1 /*simulate a number of Penney's games. */ call game /*simulate a single inning of a game. */ end /*games*/ /*keep at it until QUIT or halt. */ exit /*stick a fork in it, we're all done. */ /*──────────────────────────────────────────────────────────────────────────────────────*/ halt: say; say __ "Penney's Game was halted."; say; exit 13 r: arg ,$; do arg(1); $=$ || random(0,1); end; return $ s: if arg(1)==1 then return arg(3); return word(arg(2) 's',1) /*pluralizer.*/ /*──────────────────────────────────────────────────────────────────────────────────────*/ game: @.=; tosses=@. /*the coin toss sequence so far. */ toss1=r(1) /*result: 0=computer, 1=CBLF.*/ if \toss1 then call randComp /*maybe let the computer go first*/ if toss1 then say __ "You win the first toss, so you pick your sequence first." else say __ "The computer won first toss, the pick was: " @.comp call prompter /*get the human's guess from C.L.*/ call randComp /*get computer's guess if needed.*/ /*CBLF: carbon-based life form. */ say __ " your pick:" @.CBLF /*echo human's pick to terminal. */ say __ "computer's pick:" @.comp /* " comp.'s " " " */ say /* [↓] flip the coin 'til a win.*/ do flips=1 until pos(@.CBLF,tosses)\==0 | pos(@.comp,tosses)\==0 tosses=tosses || translate(r(1),'HT',10) end /*flips*/ /* [↑] this is a flipping coin,*/ /* [↓] series of tosses*/ say __ "The tossed coin series was: " tosses say @@@="won this toss with " flips ' coin tosses.' if pos(@.CBLF,tosses)\==0 then do; say __ "You" @@@; wins=wins+1; end else say __ "The computer" @@@ _=wins; if _==0 then _='no' say __ "You've won" _ "game"s(wins) 'out of ' games"." say; say copies('╩╦',79%2)'╩'; say return /*──────────────────────────────────────────────────────────────────────────────────────*/ prompter: oops=__ 'Oops! '; a= /*define some handy REXX literals*/ @a_z='ABCDEFG-IJKLMNOPQRS+UVWXYZ' /*the extraneous alphabetic chars*/ p=__ 'Pick a sequence of' # "coin tosses of H or T (Heads or Tails) or Quit:" do until ok; say; say p; pull a /*uppercase the answer. */ if abbrev('QUIT',a,1) then exit 1 /*the human wants to quit. */ a=space(translate(a,,@a_z',./\;:_'),0) /*elide extraneous characters. */ b=translate(a,10,'HT'); L=length(a) /*translate ───► bin; get length.*/ ok=0 /*the response is OK (so far). */ select /*verify the user response. */ when \datatype(b,'B') then say oops "Illegal response." when \datatype(a,'M') then say oops "Illegal characters in response." when L==0 then say oops "No choice was given." when L<# then say oops "Not enough coin choices." when L># then say oops "Too many coin choices." when a==@.comp then say oops "You can't choose the computer's choice: " @.comp otherwise ok=1 end /*select*/ end /*until ok*/ @.CBLF=a; @.CBLF!=b /*we have the human's guess now. */ return /*──────────────────────────────────────────────────────────────────────────────────────*/ randComp: if @.comp\=='' then return /*the computer already has a pick*/ _=@.CBLF! /* [↓] use best-choice algorithm.*/ if _\=='' then g=left((\substr(_, min(2, #), 1))left(_, 1)substr(_, 3), #) do until g\==@.CBLF!; g=r(#); end /*otherwise, generate a choice. */ @.comp=translate(g, 'HT', 10) return ``` '''output''' of a six-game session (ended by user entering a '''quit'''): ```txt ───────── The computer won first toss, the pick was: HHH ───────── Pick a sequence of 3 coin tosses of H or T (Heads or Tails) or Quit: tail tail tails ◄■■■■■■■■■■■ human's input ───────── your pick: TTT ───────── computer's pick: HHH ───────── The computer won this toss with 12 coin tosses. ───────── The tossed coin series was: HHTTHHTHTHHH ───────── You've won no games out of 1. ╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩ ───────── You win the first toss, so you pick your sequence first. ───────── Pick a sequence of 3 coin tosses of H or T (Heads or Tails) or Quit: h, h, t ◄■■■■■■■■■■■ human's input ───────── your pick: HHT ───────── computer's pick: THT ───────── The computer won this toss with 5 coin tosses. ───────── The tossed coin series was: TTTHT ───────── You've won no games out of 2. ╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩ ───────── The computer won first toss, the pick was: HHT ───────── Pick a sequence of 3 coin tosses of H or T (Heads or Tails) or Quit: heads heads heads ◄■■■■■■■■■■■ human's input ───────── your pick: HHH ───────── computer's pick: HHT ───────── The computer won this toss with 3 coin tosses. ───────── The tossed coin series was: HHT ───────── You've won no games out of 3. ╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩ ───────── The computer won first toss, the pick was: HTH ───────── Pick a sequence of 3 coin tosses of H or T (Heads or Tails) or Quit: t t h ◄■■■■■■■■■■■ human's input ───────── your pick: TTH ───────── computer's pick: HTH ───────── You won this toss with 3 coin tosses. ───────── The tossed coin series was: TTH ───────── You've won 1 game out of 4. ╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩ ───────── You win the first toss, so you pick your sequence first. ───────── Pick a sequence of 3 coin tosses of H or T (Heads or Tails) or Quit: t,h,h ◄■■■■■■■■■■■ human's input ───────── your pick: THH ───────── computer's pick: HTH ───────── You won this toss with 4 coin tosses. ───────── The tossed coin series was: TTHH ───────── You've won 2 games out of 5. ╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩ ───────── The computer won first toss, the pick was: TTH ───────── Pick a sequence of 3 coin tosses of H or T (Heads or Tails) or Quit: tth ◄■■■■■■■■■■■ human's input ───────── Oops! You can't choose the computer's choice: TTH ───────── Pick a sequence of 3 coin tosses of H or T (Heads or Tails) or Quit: tht ◄■■■■■■■■■■■ human's input ───────── your pick: THT ───────── computer's pick: TTH ───────── The computer won this toss with 3 coin tosses. ───────── The tossed coin series was: TTH ───────── You've won 2 games out of 6. ╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩╦╩ ───────── You win the first toss, so you pick your sequence first. ───────── Pick a sequence of 3 coin tosses of H or T (Heads or Tails) or Quit: quit ◄■■■■■■■■■■■ human's input ``` =={{Header|Ruby}}== ```ruby Toss = [:Heads, :Tails] def yourChoice puts "Enter your choice (H/T)" choice = [] 3.times do until (c = $stdin.getc.upcase) == "H" or c == "T" end choice << (c=="H" ? Toss[0] : Toss[1]) end puts "You chose #{choice.join(' ')}" choice end loop do puts "\n%s I start, %s you start ..... %s" % [*Toss, coin = Toss.sample] if coin == Toss[0] myC = Toss.shuffle << Toss.sample puts "I chose #{myC.join(' ')}" yC = yourChoice else yC = yourChoice myC = Toss - [yC[1]] + yC.first(2) puts "I chose #{myC.join(' ')}" end seq = Array.new(3){Toss.sample} print seq.join(' ') loop do puts "\n I win!" or break if seq == myC puts "\n You win!" or break if seq == yC seq.push(Toss.sample).shift print " #{seq[-1]}" end end ``` {{out}} ```txt Heads I start, Tails you start ..... Tails Enter your choice (H/T) THT You chose Tails Heads Tails I chose Tails Tails Heads Heads Tails Heads Heads Tails Tails Tails Heads I win! Heads I start, Tails you start ..... Heads I chose Heads Heads Heads Enter your choice (H/T) THH You chose Tails Heads Heads Heads Heads Tails Heads Tails Heads Tails Tails Tails Tails Tails Tails Tails Heads Heads You win! ``` ## Tcl {{works with|Tcl|8.6}} ```tcl package require Tcl 8.6 oo::class create Player { variable who seq seen idx constructor {name sequence} { set who $name set seq $sequence set seen {} set idx end-[expr {[string length $seq] - 1}] } method pick {} { return $seq } method name {} { return $who } method match {digit} { append seen $digit return [expr {[string range $seen $idx end] eq $seq}] } } oo::class create HumanPlayer { superclass Player constructor {length {otherPlayersSelection ""}} { fconfigure stdout -buffering none while true { puts -nonewline "What do you pick? (length $length): " if {[gets stdin pick] < 0} exit set pick [regsub -all {[^HT]} [string map {0 H 1 T h H t T} $pick] ""] if {[string length $pick] eq $length} break puts "That's not a legal pick!" } set name "Human" if {[incr ::humans] > 1} {append name " #$::humans"} next $name $pick } } oo::class create RobotPlayer { superclass Player constructor {length {otherPlayersSelection ""}} { if {$otherPlayersSelection eq ""} { set pick "" for {set i 0} {$i < $length} {incr i} { append pick [lindex {H T} [expr {int(rand()*2)}]] } } else { if {$length != 3} { error "lengths other than 3 not implemented" } lassign [split $otherPlayersSelection ""] a b c set pick [string cat [string map {H T T H} $b] $a $b] } set name "Robot" if {[incr ::robots] > 1} {append name " #$::robots"} puts "$name picks $pick" next $name $pick } } proc game {length args} { puts "Let's play Penney's Game!" # instantiate the players set picks {} set players {} while {[llength $args]} { set idx [expr {int(rand()*[llength $args])}] set p [[lindex $args $idx] new $length {*}$picks] set args [lreplace $args $idx $idx] lappend players $p lappend picks [$p pick] } # sanity check if {[llength $picks] != [llength [lsort -unique $picks]]} { puts "Two players picked the same thing; that's illegal" } # do the game loop while 1 { set coin [lindex {H T} [expr {int(rand()*2)}]] puts "Coin flip [incr counter] is $coin" foreach p $players { if {[$p match $coin]} { puts "[$p name] has won!" return } } } } game 3 HumanPlayer RobotPlayer ``` {{out|Sample Game}} ```txt Let's play Penney's Game! What do you pick? (length 3): HTH Robot picks HHT Coin flip 1 is T Coin flip 2 is H Coin flip 3 is T Coin flip 4 is T Coin flip 5 is T Coin flip 6 is H Coin flip 7 is T Coin flip 8 is T Coin flip 9 is H Coin flip 10 is T Coin flip 11 is T Coin flip 12 is T Coin flip 13 is H Coin flip 14 is T Coin flip 15 is T Coin flip 16 is H Coin flip 17 is T Coin flip 18 is T Coin flip 19 is H Coin flip 20 is T Coin flip 21 is H Human has won! ``` ## UNIX Shell {{works with|Bash}} ```sh #!/bin/bash main() { echo "Penney's Game" echo -n "Flipping to see who goes first ... " if [[ $(flip) == H ]]; then echo "I do." p2=$(choose_sequence) echo "I choose: $p2" else echo "You do." fi while true; do echo "Enter your three-flip sequence:" read p1 case "$p1" in "$p2") echo "Sequence must be different from mine";; [hHTt][hHtT][hHtT]) break;; *) echo "Sequence must be three H's or T's";; esac done p1=$(tr a-z A-Z <<<"$p1") if [ -z "$p2" ]; then p2=$(choose_sequence "$p1") echo "I choose: $p2" fi echo echo "Here we go. $p1, you win; $p2, I win." flips= while true; do flip=$(flip) echo -n $flip flips+=$flip while (( ${#flips} > 3 )); do flips="${flips#?}" done case "$flips" in *$p1) echo $'\nYou win!'; exit 0;; *$p2) echo $'\nI win!'; exit 1;; esac done } choose_sequence() { local result if (( $# )); then case "$1" in ?Hh?) result=T;; *) result=H;; esac result+="${1%?}" else result=$(flip)$(flip)$(flip) fi echo "$result" } flip() { if (( RANDOM % 2 )); then echo H else echo T fi } main "$@" ``` {{Output}} PC first: ```txt Penney's Game Flipping to see who goes first ... I do. I choose: HHT Enter your three-flip sequence: THH Here we go. THH, you win; HHT, I win. THH You win! ``` Human first: ```txt penney Penney's Game Flipping to see who goes first ... You do. Enter your three-flip sequence: HTH I choose: HHT Here we go. HTH, you win; HHT, I win. HHHT I win! ``` ## VBA ```vb Option Explicit Private Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long) Private Const HT As String = "H T" Public Sub PenneysGame() Dim S$, YourSeq$, ComputeSeq$, i&, Seq$, WhoWin$, flag As Boolean Do S = WhoWillBeFirst(Choice("Who will be first")) If S = "ABORT" Then Exit Do Debug.Print S; " start" YourSeq = Choice("Your sequence", 3) If YourSeq Like "*ABORT*" Then Exit Do Debug.Print "Your sequence : " & YourSeq ComputeSeq = vbNullString For i = 1 To 3 ComputeSeq = ComputeSeq & Random Next i Debug.Print "Computer sequence : " & ComputeSeq Seq = vbNullString Do Seq = Seq & Random Debug.Print Seq Sleep 1000 Loop While Not Winner(ComputeSeq, YourSeq, Seq, WhoWin) Debug.Print WhoWin; " win" If MsgBox(WhoWin & " win" & vbCrLf & "Play again?", vbYesNo) = vbNo Then flag = True Debug.Print "" Loop While Not flag Debug.Print "Game over" End Sub Private Function WhoWillBeFirst(YourChoice As String) As String Dim S$ S = Random Select Case YourChoice Case "ABORT": WhoWillBeFirst = YourChoice Case Else: WhoWillBeFirst = IIf(S = YourChoice, "You", "Computer") End Select End Function Private Function Choice(Title As String, Optional Seq As Integer) As String Dim S$, i&, t$ If Seq = 0 Then Seq = 1 t = Title For i = 1 To Seq S = vbNullString Do S = InputBox("Choose between H or T : ", t) If StrPtr(S) = 0 Then S = "Abort" S = UCase(S) Loop While S <> "H" And S <> "T" And S <> "ABORT" Choice = Choice & S t = Title & " " & Choice If Choice Like "*ABORT*" Then Exit For Next i End Function Private Function Random() As String Randomize Timer Random = Split(HT, " ")(CInt(Rnd)) End Function Private Function Winner(Cs$, Ys$, S$, W$) As Boolean If Len(S) < 3 Then Winner = False Else If Right(S, 3) = Cs And Right(S, 3) = Ys Then Winner = True W = "Computer & you" ElseIf Right(S, 3) = Cs And Right(S, 3) <> Ys Then Winner = True W = "Computer" ElseIf Right(S, 3) = Ys And Right(S, 3) <> Cs Then Winner = True W = "You" End If End If End Function ``` {{out}} ```txt You start Your sequence : HHT Computer sequence : TTH H HT HTT HTTH Computer win You start Your sequence : TTH Computer sequence : HHH T TT TTT TTTH You win Game over ``` ## zkl ```zkl fcn coinToss{ (0).random(2) and "H" or "T" } // (0).random(2) --> 0<=r<2 reg myBet, yourBet; if(coinToss()=="H"){ // The toss says I go first myBet=(3).pump(String,coinToss); println("I bet ",myBet); yourBet=ask("Your bet of three (H/T): ")[0,3].toUpper(); }else{ yourBet=ask("Your bet of three (H/T): ")[0,3].toUpper(); myBet=((yourBet[1]=="H") and "T" or "H") + yourBet[0,2]; println("I bet ",myBet); } print("Flipping: "); coins:=""; while(1){ print(toss:=coinToss()); coins=coins + toss; if(Void!=coins.find(yourBet)){ println(" You win!"); break; } if(Void!=coins.find(myBet)) { println(" I win!"); break; } // ignore we both won } ``` {{out}} ```txt $ zkl bbb Your bet of three (H/T): tth I bet HTT Flipping: HHHHHHTHHTHHHTHTHHHTHTHTT I win! $ zkl bbb I bet THT Your bet of three (H/T): hhh Flipping: THHH You win! ```