uva_cpp_clean/10034/10034-21.cpp

/*
  >>~~ UVa Online Judge ACM Problem Solution ~~<<

  ID: 10034
  Name: Freckles
  Problem: https://onlinejudge.org/external/100/10034.pdf
  Language: C++

  Author: Arash Shakery
  Email: [email protected]
*/

#include <math.h>
#include <stdio.h>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;


double X[102], Y[102], M[102][102];
double dist(int i, int j) {
    double x = X[i] - X[j],
        y = Y[i] - Y[j];
    return sqrt(x*x + y*y);
}


struct Edge {
    int i, j;
    double dist;
    bool operator < (const Edge& o) const {
        return dist < o.dist;
    }
};

Edge edges[102*102];
bool tr[102][102];

int main(){
    int N;
    cin>>N;
    while(N--) {
        int n;
        cin>>n;
        for(int i=0; i<n; i++)
            cin>>X[i]>>Y[i];

        int l = 0;
        for (int i=0; i<n; i++) {
            M[i][i] = 0;
            tr[i][i] = true;
            for (int j=i+1; j<n; j++) {
                Edge& e = edges[l++];
                e.i=i; e.j=j;
                e.dist = M[i][j] = M[j][i] = dist(i, j);
                tr[i][j] = tr[j][i] = false;
            }
        }

        sort(edges, edges+l);

        int c = 0, k = 0;
        double res = 0;
        while (c < n-1) {
            Edge& e = edges[k++];
            if (!tr[e.i][e.j]) {
                c++;
                res += e.dist;

                tr[e.i][e.j] = tr[e.j][e.i] = true;
                for (int i=0; i<n; i++)
                    if (tr[i][e.i])
                        for (int j=0; j<n; j++)
                            if (tr[e.j][j])
                                tr[i][j] = tr[j][i] = true;
            }
        }

        printf("%.2f\n", res);
        if (N) cout<<endl;
    }
}