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Monty Hall problem: Difference between revisions
added CL code
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Changing: 66.59
New random choice: 49.67</pre>
=={{header|Common Lisp}}==
As you can see, the SBCL RNG (Mersenne Twister) is very good, given enough iterations.
<pre>(defun make-round ()
(let ((array (make-array 3
:element-type 'bit
:initial-element 0)))
(setf (bit array (random 3)) 1)
array))
(defun show-goat (array)
(loop for i = (random 3)
when (zerop (bit array i))
return i))
(defun won? (array i)
(= 1 (bit array i)))</pre>
(progn (loop repeat #1=(expt 10 6)
when (won? (make-round) (random 3))
sum 1 into result
finally (format t "Stay: ~S%~%" (float (/ result #1# 1/100))))
(loop repeat #1#
for round = (make-round)
for initial = (random 3)
for goat = (show-goat round)
for choice = (loop for i below 3
when (and (/= i initial)
(/= i goat))
return i)
when (won? round choice)
sum 1 into result
finally (format t "Switch: ~S%~%" (float (/ result #1# 1/100)))))</pre>
<pre>CL-USER> (progn (loop repeat #1=(expt 10 6)
when (won? (make-round) (random 3))
sum 1 into result
finally (format t "Stay: ~S%~%" (float (/ result #1# 1/100))))
(loop repeat #1#
for round = (make-round)
for initial = (random 3)
for goat = (show-goat round)
for choice = (loop for i below 3
when (and (/= i initial)
(/= i goat))
return i)
when (won? round choice)
sum 1 into result
finally (format t "Switch: ~S%~%" (float (/ result #1# 1/100)))))
Stay: 33.2961%</pre>
Switch: 49.9627%
=={{header|C++}}==
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