;; Counting change.
;; Helper methods, could define them in cc too:
(define(first-denomination denominations)(car denominations))(define(except-first-denom denominations)(cdr denominations))(define(no-more? denominations)(null? denominations))(define(cc amount denominations)(cond;; If there's no change left, we have a solution
((= amount 0) 1);; If we're gone -ve amount, or there are no more kinds of coins
;; to play with, we don't have a solution.
((or(< amount 0)(no-more? denominations)) 0)(else;; number of ways to make change without the current coin type
;; plus the number of ways after subtracting the amount of the
;; current coin.
(+(cc amount (except-first-denom denominations))(cc (- amount
(first-denomination denominations))
denominations)))))(cc 100 (list 50 25 10 5 1));; 292
(cc 100 (list 100 50 20 10 5 2 1 0.5));; 104561 ... wow.

jz