hdu 1596 find the safest road (Floyd)

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<cmath>
 4 using namespace std;
 5 double s[1005][1005];
 6 int main()
 7 {
 8     int n,i,j,k;
 9     while (~scanf("%d",&n))
10     {
11         for (i=1;i<=n;i++)
12         for (j=1;j<=n;j++) scanf("%lf",&s[i][j]);
13         for (k=1;k<=n;k++)//如果这步放在j循环下面就会超时。
14         for (i=1;i<=n;i++)
15         for (j=1;j<=n;j++)
16         if (s[i][j]<s[i][k]*s[k][j]) s[i][j]=s[i][k]*s[k][j];
17         scanf("%d",&n);
18         while (n--)
19         {
20             scanf("%d%d",&i,&j);
21             if (s[i][j]==0) printf("What a pity!\n");
22             else printf("%0.3lf\n",s[i][j]);
23         }
24     }
25 }