sicp_2.59-2.60

 1 #lang racket
 2 
 3 ;;;;;;;;;;;;;;;;;;;;2.59
 4 (define (element-of-set? x set)
 5   (cond ((null? set) false)
 6         ((equal? x (car set)) true)
 7         (else (element-of-set? x (cdr set)))))
 8 
 9 (define (adjoin-set x set)
10   (if (element-of-set? x set)
11       set
12       (cons x set)))
13 
14 (define (intersection-set set1 set2)
15   (cond ((or (null? set1) (null? set2)) ‘())
16         ((element-of-set? (car set1) set2)
17          (cons (car set1)
18                (intersection-set (cdr set1) set2)))
19         (else (intersection-set (cdr set1) set2))))
20 
21 (define (union-set set1 set2)
22   (cond ((null? set1) set2)
23         ((null? set2) set1)
24         ((element-of-set? (car set1) set2)
25          (union-set (cdr set1) set2))
26         (else (cons (car set1)
27                     (union-set (cdr set1) set2)))))
28 
29 ;;;;;;;;;;;;;;;;;;;2.60
30 (define (new-element-of-set? x set)
31   (cond ((null? set) false)
32         ((equal? x (car set)) true)
33         (else (element-of-set? x (cdr set)))))
34 
35 (define (new-adjion-set x set)
36   (cons x set))
37 
38 (define (new-union-set set1 set2)
39   (append set1 set2))
40 
41 (define (new-intersection-set set1 set2)
42  (cond ((or (null? set1) (null? set2)) ‘())
43         ((element-of-set? (car set1) set2)
44          (cons (car set1)
45                (intersection-set (cdr set1) set2)))
46         (else (intersection-set (cdr set1) set2))))
47 
48 ;;;;;;;;;;;;;;;;;test
49 (union-set ‘(1 2 3 4) ‘(0 3 5 1))
50 (new-union-set ‘(1 2 3 2 4) ‘(3 4 3 2 1 5))
51 (new-intersection-set ‘(1 3 3 2 4) ‘(2 3 2 2 4 5 1))
52 ;;;;;;;;;;;;;;;;adjion和union分别变为O（1）和O（n）
53 ;;;;;;;;;;;;;;;;其他不变