[kuangbin带你飞]专题四 最短路练习 B POJ 2253

#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
#include<vector>
#include<cmath>
using namespace std;
const int maxn=200+5;
vector<pair<int,double> >E[maxn];
struct point{
int x,y;
}p[maxn];
int n;
double d[maxn];
double cal(int i,int j)
{
return sqrt((p[i].x-p[j].x)*(p[i].x-p[j].x)+(p[i].y-p[j].y)*(p[i].y-p[j].y));
}

int main()
{
int num=1;
while(scanf("%d",&n) && n)
{
for(int i=0;i<=n;i++)
{
d[i]=1e9;
E[i].clear();
p[i].x=0,p[i].y=0;
}
for(int i=1;i<=n;i++)
{
scanf("%d%d",&p[i].x,&p[i].y);
for(int j=i-1;j>=1;j--)
{
double temp=cal(i,j);
E[i].push_back(make_pair(j,temp));
E[j].push_back(make_pair(i,temp));
}
}

int s=1,e=2;
d[s]=0;
priority_queue<pair<double,int> >q;
q.push(make_pair(-d[s],s));
while(!q.empty())
{
int now=q.top().second;
q.pop();
for(int i=0;i<E[now].size();i++)
{
int v=E[now][i].first;
if(d[v]>E[now][i].second && d[v]>d[now])
{
d[v]=max(E[now][i].second,d[now]);
q.push(make_pair(-d[v],v));
}
}
}
printf("Scenario #%d\n",num++);
printf("Frog Distance = %.3f\n\n",d[2]);
}
}