Penney's game: Difference between revisions
added Factor
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Enter your choice (H/T)
</pre>
=={{header|Factor}}==
<lang 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</lang>
{{out}}
<pre>
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.
</pre>
=={{header|Go}}==
<lang Go>
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