答复: 有1元，5元，10元，20元，50元，问组成100元有多少种情况

freizl

SICP, 1.2.2  Tree Recursion
有详细的解释
http://mitpress.mit.edu/sicp/full-text/book/book-Z-H-11.html#%_sec_1.2.2

CLISP的一种实现

(defparameter us-coins (list 50 25 10 5 1))(defun no-more? (coin-values)  (null coin-values))(defun except-first-denomination (coin-values)  (cdr coin-values))(defun first-denomination (coin-values)  (car coin-values))(defun cc (amount coin-values)  (cond ((= amount 0) 1)        ((or (< amount 0) (no-more? coin-values)) 0)        (t         (+ (cc amount                (except-first-denomination coin-values))            (cc (- amount                   (first-denomination coin-values))                coin-values)))))(defun count-change (amount &optional (coin-values us-coins))  (cc amount coin-values));;; test, assertEquals 343(print (count-change 100 '(50 20 10 5 1)))