Floyd最短路径

http://acm.hdu.edu.cn/showproblem.php?pid=1596

Problem : 1596 ( find the safest road )     Judge Status : Accepted
RunId : 10374805    Language : C++    Author : l1285556798
Code Render Status : Rendered By HDOJ C++ Code Render Version 0.01 Beta

#include<stdio.h>
#include<string.h>
#define maxn 1001
double map[maxn][maxn];
int n,q;
void floyd()
{
    for(int k=1;k<=n;k++)
        for(int i=1;i<=n;i++)
         for(int j=1;j<=n;j++)
         if(map[i][j]<map[i][k]*map[k][j])
         map[i][j]=map[i][k]*map[k][j];
}
int main()
{
    while(scanf("%d",&n)!=EOF)
    {
        memset(map,0,sizeof(map));
        for(int i=1;i<=n;i++)
            for(int j=1;j<=n;j++)
            scanf("%lf",&map[i][j]);
        floyd();
        scanf("%d",&q);
        while(q--)
        {
            int a,b;
            scanf("%d%d",&a,&b);
            if(!map[a][b])
                printf("What a pity!\n");
            else
                printf("%.3lf\n",map[a][b]);
        }
    }
    return 0;
}