최소 스패닝 트리 - 1197

//최소 스패닝 트리 - 1197
 
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
 
int V, E;
vector<pair<int, pair<int, int>>> edges;
 
struct DisjointSet
{
    vector<int> parent, rank;
    DisjointSet(int n) : parent(n+1), rank(n+1, 1)
    {
        for(int i = 1; i<=n; ++i)
            parent[i] = i;
    }
 
    int find(int u)
    {
        if(u == parent[u]) return u;
        return parent[u] = find(parent[u]);
    }
 
    void merge(int u, int v)
    {
        u = find(u); v = find(v);
        if(u == v) return;
        if(rank[u] > rank[v]) swap(u, v);
        parent[u] = v;
        if(rank[u] == rank[v]) ++rank[v];
    }
};
 
int kruskal()
{
    int ans = 0;
    int cost, x, y;
    DisjointSet sets(V);
    for(int i =0; i<E; ++i)
    {
        cost = edges[i].first;
        x = edges[i].second.first;
        y = edges[i].second.second;
 
        if(sets.find(x) == sets.find(y)) continue;
 
        sets.merge(x, y);
        ans += cost;
    }
    return ans;
}
 
int main()
{
    cin >> V >> E;
    edges = vector<pair<int, pair<int, int>>>(E);
    int x, y, r;
    for(int i = 0; i<E; ++i)
    {
        cin >> x >> y >> r;
        edges[i].first = r;
        edges[i].second.first = x;
        edges[i].second.second = y;        
    }
    sort(edges.begin(), edges.end());
 
    cout << kruskal() << "\n";
}