poj 1125 Stockbroker Grapevine

用floyd算法求出任意两点之间的距离，然后从一点出发找到其他点的最大的距离，找从所有点出发到其他点里的最大距离这一集合的最小值，就是所求.

#include<stdio.h>
#include<string.h>
#define MAXN 110

int n, m, d[MAXN][MAXN];

int main()
{
    while(scanf("%d",&n))
    {
        if(n == 0) break;
        memset(d,0x3f,sizeof(d));
        for(int i = 1; i <= n; i ++)
        {
            scanf("%d",&m);
            for(int j = 0; j < m; j ++)
            {
                int a, b;
                scanf("%d%d",&a,&b);
                d[i][a] = b;
            }
        }
        for(int k = 1; k <= n; k ++)
        for(int i = 1; i <= n; i ++)
            for(int j = 1; j <= n; j ++)
            {
                if(d[i][j] > d[i][k] + d[k][j])
                    d[i][j] = d[i][k] + d[k][j];
            }
        int max;
        int min = 0x7fffffff;
        int flag = 0;
        for(int i = 1; i <= n; i ++)
        {
            max = 0;
            for(int j = 1; j <= n; j ++)
            {
                if(i != j && max < d[i][j])
                    max = d[i][j];
            }
            if(min > max) {min = max;flag = i;}
        }
        if(min > 10000000) printf("disjoint\n");
        else printf("%d %d\n",flag,min);
    }
    return 0;
}