10034 Freckles

#include <bits/stdc++.h>
using namespace std;
typedef pair <int , double> pi;
typedef pair<double , int> pd;
typedef vector <pi> vc;
vc vertex[1002];
int arr[1002];
double arr1[1002] , arr2[1002];
priority_queue <pd > pq;

void prims_algo(int src)
{
    arr[src] = 1;

    for(int i = 0; i < vertex[src].size(); i++)
    {
        pi v = vertex[src][i];
        if(arr[v.first] == -1)
        {

            pq.push(make_pair(-v.second , -v.first));
        }
    }
}
int main()
{
    ios_base :: sync_with_stdio(0);
    cin.tie(0);
   int tes;
   cin >> tes;
   bool f = false;
   while(tes--)
   {
       int n;

       cin >> n;
       memset(arr,-1 , sizeof arr);
       for(int i = 0; i < n; i++)
       {
           cin >> arr1[i] >> arr2[i];
       }
       for(int i = 0; i < n; i++)
       {
           for(int j = i + 1; j < n; j++)
           {
               double Cost=sqrt((arr1[j] - arr1[i])*( arr1[j] - arr1[i] )+( arr2[j] - arr2[i]) * ( arr2[j] - arr2[i]));
               vertex[i].push_back(make_pair(j , Cost));
               vertex[j].push_back(make_pair(i , Cost));

           }
       }

       double mst = 0;

       prims_algo(0);
       while(pq.size())
       {
           pd front = pq.top();
           pq.pop();
            int u = - front.second ;
           double w = -front.first;
           if(arr[u] == -1)
           {
               mst += w;
               prims_algo(u);
           }

       }

      if(f) printf("\n");  f = true;
        printf("%.2lf\n", mst);

        for(int i = 0;  i < n + 1; i++)
            vertex[i].clear();


   }

}