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- #include <iostream>
- using namespace std;
- const int maxn = 1e5 + 10;
- int idx[maxn];
- int sz[maxn];
- void init() {
- for(int i = 0; i < maxn; i++) {
- idx[i] = i;
- sz[i] = 1;
- }
- }
- int find_root(int A) {
- while(idx[A] != A) {
- idx[A] = idx[idx[A]];
- A = idx[A];
- }
- return A;
- }
- void unite(int A, int B) {
- int root_A = find_root(A);
- int root_B = find_root(B);
- if(root_A != root_B) {
- if(sz[root_A] < sz[root_B]) {
- sz[root_B] += sz[root_A];
- idx[root_A] = idx[root_B];
- }
- else {
- idx[root_B] = idx[root_A];
- sz[root_A] += sz[root_B];
- }
- }
- }
- bool check_if_they_belong_to_same_set(int A, int B) {
- return find_root(A) == find_root(B);
- }
- int main()
- {
- init();
- int n, m;
- cin >> n >> m;
- vector<pair<int, pair<int, int>>> graph;
- for(int i = 0; i < m; i++) {
- int a, b, c;
- cin >> a >> b >> c;
- graph.push_back(make_pair(c, make_pair(a, b)));
- }
- sort(graph.begin(), graph.end());
- int res = 0;
- for(int i = 0; i < m; i++) {
- int a = graph[i].second.first;
- int b = graph[i].second.second;
- int c = graph[i].first;
- if(!check_if_they_belong_to_same_set(a, b)) {
- unite(a, b);
- res += c;
- }
- }
- cout << res << endl;
- }
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