HDU 1596 find the safest road

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <algorithm>
 6 #include <climits>
 7 #include <vector>
 8 #include <queue>
 9 #include <cstdlib>
10 #include <string>
11 #include <set>
12 #include <stack>
13 #define LL long long
14 #define pii pair<int,int>
15 #define INF 0x3f3f3f3f
16 using namespace std;
17 const int maxn = 1010;
18 double mp[maxn][maxn];
19 int n,m;
20 int main() {
21     int i,j,k;
22     while(~scanf("%d",&n)){
23         for(i = 1; i <= n; i++){
24             for(j = 1; j <= n; j++)
25                 scanf("%lf",mp[i]+j);
26         }
27         for(k = 1; k <= n; k++){
28             for(i = 1; i <= n; i++){
29                 for(j = 1; j <= n; j++){
30                     double ret = mp[i][k]*mp[k][j];
31                     if(ret > mp[i][j]) mp[i][j] = ret;
32                 }
33             }
34         }
35         scanf("%d",&m);
36         for(k = 0; k < m; k++){
37             scanf("%d %d",&i,&j);
38             if(mp[i][j] == 0) puts("What a pity!");
39             else printf("%.3f\n",mp[i][j]);
40         }
41     }
42     return 0;
43 }