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 ;A graph is a (vectorof (listof nodes)).
5 
6 ;neighbors : node graph -> (listof nodes)
7 ;Return the neighbors of anode given agraph.
8 
9 (define (neighbors anode agraph)
10   (vector-ref agraph anode)) 
11 
12 
13 (define G (vector '(1 4)
14                   '(4 5)
15                   '(3)
16                   empty
17                   '(2 5)
18                   '(3 6)
19                   empty))
20 
21 ;find-route : node node graph -> (listof nodes)
22 ;Find a route from ori to dest given G and return the route as a (listof nodes).
23 
24 (define (find-route ori dest G)
25   (cond
26     [(= ori dest) (list ori)]
27     [else (local ((define possible-route (find-route/list (neighbors ori G) dest G)))
28             (cond [(boolean? possible-route) false]
29                   [else (cons ori possible-route)]))]))
30 
31 ;find-route/list : (listof nodes) node graph -> (listof nodes)
32 ;Find a route from lo-ori (listof nodes) to dest given G and return the route as a (listof nodes).
33 
34 (define (find-route/list lo-ori dest G)
35   (cond
36     [(empty? lo-ori) false]
37     [else (local ((define possible-route (find-route (first lo-ori) dest G)))
38             (cond
39               [(boolean? possible-route) (find-route/list (rest lo-ori) dest G)]
40               [else possible-route]))]))