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;

}