1 ;; The first three lines of this file were inserted by DrScheme. They record metadata
2 ;; about the language level of this file in a form that our tools can easily process.
3 #reader(lib "htdp-advanced-reader.ss" "lang")((modname |29.3|) (read-case-sensitive #t) (teachpacks ((lib "draw.ss" "teachpack" "htdp") (lib "arrow.ss" "teachpack" "htdp") (lib "gui.ss" "teachpack" "htdp"))) (htdp-settings #(#t constructor repeating-decimal #t #t none #f ((lib "draw.ss" "teachpack" "htdp") (lib "arrow.ss" "teachpack" "htdp") (lib "gui.ss" "teachpack" "htdp")))))
4 (define G1
5   '((A (B E))
6     (B (E F))
7     (C (D))
8     (D ())
9     (E (C F))
10     (F (D G))
11     (G ())))
12 
13 (define G2 (vector '(1 4)
14                    '(4 5)
15                    '(3)
16                    empty
17                    '(2 5)
18                    '(3 6)
19                    empty))
20 
21 (define (find-route1 ori dest G)
22   (local ((define (find-route ori dest G)
23             (cond
24               [(symbol=? ori dest) (list ori)]
25               [else (local ((define possible-route (find-route/list (neighbors ori G) dest G)))
26                       (cond
27                         [(boolean? possible-route) false]
28                         [else (cons ori possible-route)]))]))
29           (define (find-route/list lo-ori dest G)
30             (cond
31               [(empty? lo-ori) false]
32               [else (local ((define possible-route (find-route (first lo-ori) dest G)))
33                       (cond [(boolean? possible-route) (find-route/list (rest lo-ori) dest G)]
34                             [else possible-route]))]))
35           (define (assf op aloxy)
36             (cond
37               [(empty? aloxy) false]
38               [(op (first (first aloxy))) (first aloxy)]
39               [else (assf op (rest aloxy))]))
40           (define (neighbors anode G)
41             (first (rest (assf (lambda (x) (equal? anode x)) G)))))
42     (find-route ori dest G)))
43 
44 (define (find-route2 ori dest G)
45   (local ((define (find-route ori dest G)
46             (cond
47               [(= ori dest) (list ori)]
48               [else (local ((define possible-route (find-route/list (neighbors ori G) dest G)))
49                       (cond [(boolean? possible-route) false]
50                             [else (cons ori possible-route)]))]))
51           (define (find-route/list lo-ori dest G)
52             (cond
53               [(empty? lo-ori) false]
54               [else (local ((define possible-route (find-route (first lo-ori) dest G)))
55                       (cond
56                         [(boolean? possible-route) (find-route/list (rest lo-ori) dest G)]
57                         [else possible-route]))]))
58           (define (neighbors anode agraph)
59             (vector-ref agraph anode)))
60     (find-route ori dest G)))
61 
62 (define n 100000)
63 (time (andmap (lambda (x) (equal? (find-route1 'A 'G G1)
64                                   (list 'A 'B 'E 'F 'G))) (build-list n identity)))
65 (time (andmap (lambda (x) (equal? (find-route2 0 6 G2)
66                                   (list 0 1 4 5 6))) (build-list n identity)))