⚠️ 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!
```