Harta3

#include <bits/stdc++.h>
using namespace std;
ifstream fin("harta3.in");
ofstream fout("harta3.out");
struct Points
{
    double x,y;
};
Points V[101];
const double inf=(1<<20)*1.0;
int N,P[101];
double A[101][101],S,minn;

double distance(Points A,Points B)
{
    return sqrt(pow(B.x-A.x,2)+pow(B.y-A.y,2)*1.0);
}

int main()
{
    fin>>N;
    for(int i=1;i<=N;++i)
        fin>>V[i].x>>V[i].y;
    for(int i=1;i<=N;++i)
        for(int j=1;j<=N;++j)
            if(i!=j)
                A[i][j]=distance(V[i],V[j]);
    for(int i=2;i<=N;++i)
        P[i]=1;
    int nr=0;
    for(int k=1;k<N;++k)
    {
        minn=inf;
        for(int i=1;i<=N;++i)
            if(P[i]&&A[P[i]][i]<minn)
                minn=A[P[i]][i],nr=i;
        S+=A[P[nr]][nr];
        for(int i=1;i<=N;++i)
            if(P[i]&&A[P[i]][i]>A[i][nr])
                P[i]=nr;
        P[nr]=0;
    }
    fout<<fixed<<setprecision(4)<<S;
    return 0;
}