2_19.scm

(define (cc amount coin-values)
  (cond ((= amount 0) 1)
        ((or (< amount 0) (no-more? coin-values)) 0)
        (else
         (+ (cc amount
                (except-first-denomination coin-values))
            (cc (- amount
                   (first-denomination coin-values))
                coin-values)))))

(define no-more? null? )
(define except-first-denomination cdr)
(define first-denomination car)
(define us-coins (list 50 25 10 5 1))
(define uk-coins (list 100 50 20 10 5 2 1 0.5))

;(cc 100 us-coins)
;(cc 50 uk-coins)
;
; Reversing the order of coins doesn't affect a value returned by cc, but it
; changes the structure of a recursion tree.