Prim

/*
    Task    : Prim
    Author  : Phumipat C. [MAGCARI]
    Language: C++
    Created : 30 July 2022 [09:03]
*/
#include<bits/stdc++.h>
using namespace std;
struct A{
    int v,w;
    bool operator < (const A&o) const{
        return w>o.w;
    }
};
priority_queue<A > heap;
vector<A > g[100010];
int mark[100010];
int main(){
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);

    int n,m,u,v,w;
    cin >> n >> m;

    for(int i=1;i<=m;i++){
        cin >> u >> v >> w;
        g[u].push_back({v,w});
        g[v].push_back({u,w});
    }

    mark[1] = 1;
    for(auto x:g[1])
        heap.push(x);

    int sum = 0;
    while(!heap.empty()){
        A now = heap.top();
        heap.pop();
        if(mark[now.v]) continue;
        sum+=now.w;
        mark[now.v] = 1;
        for(auto x:g[now.v]){
            if(mark[x.v])   continue;
            heap.push(x);
        }
    }

    return 0;
}