1 #lang racket
2
3 ;;;;;;;;;;;;;;;;;
2.40
4 (define nil
'())
5
6 (define (accumulate op intial seq)
7 (
if (
null?
seq)
8 intial
9 (op (car seq)
10 (accumulate op intial (cdr seq)))))
11
12 (define (enumerate-
interval low high)
13 (
if (>
low high)
14 nil
15 (cons low (enumerate-interval (+ low
1) high))))
16
17 (define (make-pair-
sum pair)
18 (list (car pair) (cadr pair) (+
(car pair) (cadr pair))))
19
20 (define (prime-sum?
pair)
21 (prime? (+
(car pair) (cadr pair))))
22
23 (define (prime?
n)
24 (define (test number)
25 (cond ((>
(square number) n) #t)
26 ((= (remainder n number)
0) #f)
27 (
else (test (+ number
1)))))
28 (test
2))
29
30 (define (square x)
31 (*
x x))
32
33 (define (unique-
pairs n)
34 (accumulate append
35 nil
36 (map (lambda (i)
37 (map (lambda (j) (list i j))
38 (enumerate-interval
1 (- i
1))))
39 (enumerate-interval
1 n))))
40
41 ;;;;;;;;test
42 (unique-pairs
5)
43 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
44 (define (prime-sum-
pairs n)
45 (map make-pair-
sum
46 (filter prime-sum?
47 (unique-
pairs n))))
48
49 ;;;;;;;;;test
50 (prime-sum-pairs
5)
转载于:https://www.cnblogs.com/tclan126/p/6417796.html
相关资源：数据结构—成绩单生成器
