USACO 2.4 Bessie Come Home

mark：就是个最短路。。。错了2次，一次是题目没读清楚，一次是自己犯2。。。

代码：

 1 # include <stdio.h>
 2 
 3 
 4 int graph[210][210] ;
 5 int INF = 0x0f0f0f0f ;
 6 
 7 
 8 int min(int a, int b){return a<b?a:b;}
 9 
10 
11 int main ()
12 {
13     char ch1, ch2 ;
14     int num, p, pos, i, j, k ;
15     
16     freopen ("comehome.in", "r", stdin) ;
17     freopen ("comehome.out", "w", stdout) ;
18     
19     while (~scanf ("%d%*c", &p))
20     {
21         for (i = 0 ; i < 200 ; i++)
22         {
23             for (j = 0 ; j < 200 ; j++)
24                 if (i != j) graph[i][j] = INF ;
25                 else graph[i][j] = 0 ;
26         }
27         while (p--)
28             scanf ("%c %c %d%*c", &ch1, &ch2, &num),
29             graph[ch1][ch2] = graph[ch2][ch1] = min(graph[ch1][ch2], num) ;
30         
31         for (k = 0 ; k <= 'z' ; k++)
32             for (i = 0 ; i <= 'z' ; i++)
33                 for (j = 0 ; j <= 'z' ; j++)
34                     if (graph[i][k]+graph[k][j] < graph[i][j])
35                         graph[i][j] = graph[i][k]+graph[k][j] ;
36         pos = -1 ;
37         for (i = 'A' ; i < 'Z' ; i++)
38             if (pos == -1 || graph[i]['Z'] < graph[pos]['Z']) pos = i ;
39         printf ("%c %d
", pos, graph[pos]['Z']) ;
40     }
41     return 0 ;
42 }