Penney's game: Difference between revisions
→{{header|Common Lisp}}: Add implementation
(→{{header|UNIX Shell}}: Correct logic.) |
(→{{header|Common Lisp}}: Add implementation) |
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Thanks for playing!
</pre>
=={{header|Common Lisp}}==
{{trans|UNIX Shell}}
<lang lisp>(setf *random-state* (make-random-state t))
(defparameter *heads* #\H)
(defparameter *tails* #\T)
(defun main ()
(format t "Penney's Game~%~%")
(format t "Flipping to see who goes first ...")
(setq p2 nil)
(if (string= (flip) *heads*)
(progn (format t " I do.~%")
(setq p2 (choose-random-sequence))
(format t "I choose: ~A~%" p2))
(format t "You do.~%"))
(setq p1 nil)
(loop while (null p1) doing
(format t "Enter your three-flip sequence: ")
(setq p1 (string (read)))
(cond ((/= (length p1) 3)
(format t "Sequence must consist of three flips.~%")
(setq p1 nil))
((string= p1 p2)
(format t "Sequence must be different from mine.~%")
(setq p1 nil))
((notevery #'valid? (coerce p1 'list))
(format t "Sequence must be contain only ~A's and ~A's.~%" *heads* *tails*)
(setq p1 nil))))
(format t "You picked: ~A~%" p1)
(if (null p2)
(progn
(setq p2 (choose-optimal-sequence p1))
(format t "I choose: ~A~%" p2)))
(format t "Here we go. ~A, you win; ~A, I win.~%" p1 p2)
(format t "Flips:")
(let ((winner nil)
(flips '()))
(loop while (null winner) doing
(setq flips (cons (flip) flips))
(format t " ~A" (car flips))
(if (>= (length flips) 3)
(let ((trail (coerce (reverse (subseq flips 0 3)) 'string)))
(cond ((string= trail p1) (setq winner "You"))
((string= trail p2) (setq winner "I"))))))
(format t "~&~A win!" winner)))
(defparameter *sides* (list *heads* *tails*))
(defun flip () (nth (random 2 *random-state*) *sides*))
(defun valid? (flip) (not (null (member flip *sides*))))
(defun opposite (flip) (if (string= flip *heads*) *tails* *heads*))
(defun choose-random-sequence () (coerce (list (flip) (flip) (flip)) 'string))
(defun choose-optimal-sequence (against)
(let* ((opposed (coerce against 'list))
(middle (cadr opposed))
(my-list (list (opposite middle) (car opposed) middle)))
(coerce my-list 'string)))
(main)</lang>
{{Out}}
Computer player first:
<pre>Penney's Game
Flipping to see who goes first ... I do.
I choose: THH
Enter your three-flip sequence: TTH
You picked: TTH
Here we go. TTH, you win; THH, I win.
Flips: T T T H
You win!</pre>
Human player first:
<pre>Penney's Game
Flipping to see who goes first ...You do.
Enter your three-flip sequence: HTT
You picked: HTT
I choose: HHT
Here we go. HTT, you win; HHT, I win.
Flips: H T T
You win!</pre>
=={{header|D}}==
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