hdu 1596 find the safest road

#include <iostream>
#include <iomanip>
#include <cstring>
using namespace std;
typedef long long LL;

int visited[1005],n,q;
double safety[1005][1005];
double dest[1005];
int main(){
  // freopen("test.in","r",stdin);
  while (scanf("%d",&n) != EOF){
    for (int i=1;i<=n;i++){
      for (int j=1;j<=n;j++){
        scanf("%lf",&safety[i][j]);
      }
    }
    scanf("%d",&q);
    for (int i=1;i<=q;i++){
      int src,des;
      memset(visited,0,sizeof(visited));
      memset(dest,0,sizeof(dest));
      scanf("%d %d",&src,&des);
      for (int j=1;j<=n;j++){
        dest[j] = safety[src][j];
      }
      dest[src] = 1;
      visited[src] = 1;
      int finish = 0;
      while (!finish){
        int maxi = 0;
        double maxdes = -1;
        for (int j=1;j<=n;j++){
          // cout << dest[j] << " ";
          if (!visited[j] && dest[j] > maxdes){
            maxi = j; maxdes = dest[j];
          }
        }
        // cout << endl;
        if (maxi == 0){
          finish = 1; break;
        }
        visited[maxi] = 1;
        for (int j=1;j<=n;j++){
          if (!visited[j]){
            dest[j] = max(dest[j],dest[maxi] * safety[maxi][j]);
          }
        }
      }
      if (dest[des] != 0)
        printf("%.3lf\n",dest[des]);
      else
        printf("What a pity!\n");
    }
  }
  return 0;
}