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。

 #include<stdio.h>
 #include<string.h>
 #include<stdlib.h>
 #define MAXN 22
 int road[MAXN][MAXN], path[MAXN], visit[MAXN], link[MAXN];
 int n, num, lastnum, huge;

 int cmp(const void *a, const void *b)
 {
     return *(int *)a - *(int *)b;
 }

 void previous(int cur)
 {
     int i;
     link[lastnum++] = cur;
     visit[cur] = ;
     for(i=; i<=num; ++i)
     {
         if(road[cur][i] && !visit[i])
         previous(i);
     }
     return;
 }

 void Traverse(int cur, int des, int cnt)
 {
     int i, j, temp;
     if(cur == des)
     {
         j = ;
         printf("");
         for(i=; i<cnt; ++i)
         {
             j = ;
             printf(" %d", path[i]);
         }
         printf("\n");
         n += j;
         return;
     }
     for(i=; i<lastnum; ++i)
     {
         temp = link[i];
         if(road[cur][temp] && !visit[temp])
         {
             path[cnt] = temp;
             visit[temp] = ;
             Traverse(temp, des, cnt+);
             visit[temp] = ;
         }
     }
 }

 int main()
 {
     #ifndef ONLINE_JUDGE
     freopen("input.txt", "r", stdin);
     #endif
     int i, j, des, from, to, t=;
     while(scanf("%d", &des) != EOF)
     {
         memset(road, , sizeof(road));
         memset(visit, , sizeof(visit));
         num = ;
         while(scanf("%d%d", &from, &to) != EOF)
         {
             if(!from && !to) break;
             road[from][to] = road[to][from] = ;
             if(num < from) num = from;
             if(num < to) num = to;
         }
         n = ;
         lastnum = ;
         previous(des);
         memset(visit, , sizeof(visit));
         qsort(link, lastnum, sizeof(int), cmp);
         visit[] = ;
         printf("CASE %d:\n", ++t);
         Traverse(, des, );
         printf("There are %d routes from the firestation to streetcorner %d.\n", n, des);
     }
     return ;
 }