1 (define (fib n)
2   (cond ((= n 0) 0)
3 	((= n 1) 1)
4 	(else (+ (fib (- n 1))
5 		 (fib (- n 2))))))
6 
7 (define (fib n)
8   (fib-iter 1 0 n))
9 (define (fib-iter a b count)
10   (if (= count 0)
11       b
12       (fib-iter (+ a b) a (- count 1))))
13 
14 (define (count-change cents coins)
15   (cond ((= coins 0) 0)
16 	((< cents 0) 0)
17 	((= cents 0) 1)
18 	(else (+ (count-change cents (- coins 1))
19 		 (count-change (- cents (largest-coin-value coins)) coins)))))
20 
21 (define (largest-coin-value coins)
22   (cond ((= coins 5) 50)
23 	((= coins 4) 25)
24 	((= coins 3) 10)
25 	((= coins 2) 5)
26 	((= coins 1) 1)))
27 
28 (count-change 0 0)
29 ;; 0
30 (count-change 1 0)
31 ;; 0
32 (count-change 0 1)
33 ;; 1
34 (count-change 1 1)
35 ;; 1
36 (count-change 2 1)
37 ;; 1
38 (count-change 2 2)
39 ;; 1
40 (count-change 100 5)
41 
42 (define (count-change amount)
43   (cc amount 5))
44 (define (cc amount kinds-of-coins)
45   (cond ((= amount 0) 1)
46 	((or (< amount 0) (= kinds-of-coins 0)) 0)
47 	(else (+ (cc amount
48 		     (- kinds-of-coins 1))
49 		 (cc (- amount
50 			(first-denomination kinds-of-coins))
51 		     kinds-of-coins)))))
52 (define (first-denomination kinds-of-coins)
53   (cond ((= kinds-of-coins 1) 1)
54 	((= kinds-of-coins 2) 5)
55 	((= kinds-of-coins 3) 10)
56 	((= kinds-of-coins 4) 25)
57 	((= kinds-of-coins 5) 50)))