hdu 4463 Outlets

#include<bits/stdc++.h>
using namespace std;
double x[100+5],y[100+5];
double e[100+5][100+5];
const double inf=99999999;
int main()
{
    int n,i,j,k;
    double low[100+5],ans;
    while(~scanf("%d",&n))
    {
        for(i=0;i<n;i++)
            scanf("%lf%lf",&x[i],&y[i]);
        for(i=0;i<n;i++)
            for(j=0;j<n;j++)
        {
            if(i==j) e[i][j]=inf;
            else
            {
                e[i][j]=e[j][i]=sqrt((x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]));
            }
        }
        for(i=0;i<n;i++)
            low[i]=e[0][i];
        low[0]=-1;
        ans=0;
        for(i=1;i<n;i++)
        {
            double t=inf;
            for(k=0;k<n;k++)
            {
                if(low[k]!=-1&&low[k]<t)
                {
                    j=k;
                    t=low[k];
                }
            }
            ans+=t;
            low[j]=-1;
            for(k=0;k<n;k++)
            {
                low[k]=min(low[k],e[j][k]);
            }
        }
        printf("%.2f\n",ans);
    }
    return 0;
}