1.2.2-count-change.rkt

#lang sicp
(define (count-change amount)
  (cc amount 5))

(define (cc amount kinds-of-coins)
  (cond ((= amount 0) 1)
    ((or (< amount 0) (= kinds-of-coins 0)) 0)
    (else (+ (cc amount
              (- kinds-of-coins 1))
          (cc (- amount
                (first-denomination kinds-of-coins))
                kinds-of-coins)))))

(define (first-denomination kinds-of-coins)
  (cond ((= kinds-of-coins 1) 1)
        ((= kinds-of-coins 2) 5)
        ((= kinds-of-coins 3) 10)
        ((= kinds-of-coins 4) 25)
        ((= kinds-of-coins 5) 50)))