hdu 1596 find the safest road (最短路)

/*
floyd直接水过
*/
#include<cstdio>
#include<cstring>
#include<iostream>
#define N 1001
using namespace std;
int n,x,y;
double road

,t;
int main()
{
while(scanf("%d",&n)!=EOF)
{
memset(road,0,sizeof(road));
for(int i=1;i<=n;i++)
{
for(int j=1;j<=n;j++)
{
scanf("%lf",&t);
if(t>road[i][j])
{
road[i][j]=t;
road[j][i]=t;
}
}
}
for(int k=1;k<=n;k++)
{
for(int i=1;i<=n;i++)
{
if(road[i][k])
for(int j=1;j<=n;j++)
{
if(road[i][j]<road[i][k]*road[k][j])
{
road[i][j]=road[i][k]*road[k][j];
}
}
}
}
scanf("%d",&n);
for(int i=1;i<=n;i++)
{
scanf("%d%d",&x,&y);
if(road[x][y]!=0)
printf("%.3lf\n",road[x][y]);
else
printf("What a pity!\n");
}
}
}

/*spfa*/
#include<iostream>
#include<cstring>
#include<cstdio>
#include<queue>
using namespace std;
double map[1001][1001],dis[1001];
int visit[1001],s,e,n;
void SPFA(int s)
{
int p,i;
queue<int> qu;
qu.push(s);
visit[s]=1;
dis[s]=1;
while(!qu.empty())
{
p=qu.front();
qu.pop();
visit[p]=0;
for(i=1;i<=n;i++)
{
if(map[p][i]==0||p==i)
continue;
if(dis[p]*map[p][i]>dis[i])
{
dis[i]=dis[p]*map[p][i];
if(visit[i]==0)
{
visit[i]=1;
qu.push(i);
}
}
}
}
}
int main()
{
freopen("test.txt","r",stdin);
int i,j,m;
while(scanf("%d",&n)!=EOF)
{
for(i=1;i<=n;i++)
{
for(j=1;j<=n;j++)
{
scanf("%lf",&map[i][j]);
}
}
scanf("%d",&m);
while(m--)
{
scanf("%d%d",&s,&e);
for(i=1;i<=n;i++)
{
visit[i]=0;
dis[i]=0;
}
SPFA(s);
if(dis[e]!=0)
printf("%.3lf\n",dis[e]);
else
puts("What a pity!");
}
}
return 0;
}