Bai3_KrusKal_algo

int  find_set(int i, int* parent) {
  // If i is the parent of itself
  if (i == parent[i])
    return i;
  else
    // Else if i is not the parent of itself
    // Then i is not the representative of his set,
    // so we recursively call Find on its parent
    return find_set(parent[i],parent);
}

void  union_set(int u, int v,int* parent) {
  parent[u] = parent[v];
}
int kruskalMST() {
     vector<pair<int, pair<int, int>> > T;  // mst
    int* parent = new int[V];
  for (int i = 0; i < V; i++) parent[i] = i;
     int i, uRep, vRep;
  sort(edges.begin(),edges.end());  // increasing weight
  for (i = 0; i < (int)edges.size(); i++) {
    uRep = find_set(edges[i].second.first,parent);
    vRep = find_set(edges[i].second.second,parent);
    if (uRep != vRep) {
      T.push_back(edges[i]);  // add to tree
      union_set(uRep, vRep,parent);
    }
  }
  int res = 0;
   for (int i = 0; i < (int)T.size(); i++) {
      res = res + T[i].first;
  }
  delete[] parent;
  return res;
}