19/02/20 02:51:47.69 qYIek1dL.net
>>255
;; Common Lisp
(let ((prime (list 2)))
(defun primep (n)
(loop for i from (1+ (car prime)) upto n
unless (find-if (lambda (j) (zerop (mod i j))) prime :from-end t)
do (push i prime))
(find n prime)))
(defun nearest (i j)
(/ (floor (+ (* i (expt 10 j)) 0.5)) (expt 10 j)))
(loop with cards = (loop for i from 1 to 8 nconc (make-list (- 9 i) :initial-element i))
and n = 0 and p = 0
for one in cards
do (loop for two in (remove one cards :count 1)
do (incf n)
if (primep (+ (* 10 one) two)) do (incf p))
finally (format t "~,3F~%" (nearest (* (/ p n)) 3)))