Uva 208 - Firetruck

【题目链接】http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=24&page=show_problem&problem=144

【随笔侃述】这题感想多过于解题的思路，TL不可避免，很难想象1Y过的是何方神圣，当然不敢否定有经验和敢于尝试的人会在TL几次后马上领悟灯亮后敲出AC的代码，需要预处理的原因是：尽管Case可能给你很多跟1连通的点但最终1跟目的之间能连通的路径去找不到，这得消耗很多的时间做无用功。TL的原因就可能出在此处

【解题思路】现将所有能连通到目的点的点放入一个数组，来一个排序（题目告诉你按顺序输出而不会是special judge）然后再进行深度查找，遍历输出。

 1 #include<stdio.h>
 2 #include<string.h>
 3 #include<stdlib.h>
 4 #define MAXN 22
 5 int road[MAXN][MAXN], path[MAXN], visit[MAXN], link[MAXN];
 6 int n, num, lastnum, huge;
 7 
 8 int cmp(const void *a, const void *b)
 9 {
10     return *(int *)a - *(int *)b;
11 }
12 
13 void previous(int cur)
14 {
15     int i;
16     link[lastnum++] = cur;
17     visit[cur] = 1;
18     for(i=1; i<=num; ++i)
19     {
20         if(road[cur][i] && !visit[i])
21         previous(i);    
22     }
23     return;
24 }
25 
26 void Traverse(int cur, int des, int cnt)
27 {
28     int i, j, temp;
29     if(cur == des)
30     {
31         j = 0;
32         printf("1");
33         for(i=0; i<cnt; ++i)
34         {
35             j = 1;
36             printf(" %d", path[i]);
37         }
38         printf("\n");
39         n += j;
40         return;
41     }
42     for(i=0; i<lastnum; ++i)
43     {
44         temp = link[i];
45         if(road[cur][temp] && !visit[temp])
46         {
47             path[cnt] = temp;
48             visit[temp] = 1;
49             Traverse(temp, des, cnt+1);
50             visit[temp] = 0; 
51         }
52     }    
53 }
54 
55 int main()
56 {
57     #ifndef ONLINE_JUDGE
58     freopen("input.txt", "r", stdin);
59     #endif
60     int i, j, des, from, to, t=0;
61     while(scanf("%d", &des) != EOF)
62     {
63         memset(road, 0, sizeof(road));
64         memset(visit, 0, sizeof(visit));
65         num = 0;
66         while(scanf("%d%d", &from, &to) != EOF)
67         {
68             if(!from && !to) break;
69             road[from][to] = road[to][from] = 1;
70             if(num < from) num = from;
71             if(num < to) num = to;
72         }
73         n = 0;
74         lastnum = 0;
75         previous(des);
76         memset(visit, 0, sizeof(visit));
77         qsort(link, lastnum, sizeof(int), cmp);
78         visit[1] = 1;
79         printf("CASE %d:\n", ++t);
80         Traverse(1, des, 0);
81         printf("There are %d routes from the firestation to streetcorner %d.\n", n, des);
82     }
83     return 0;
84 }