СНМ

#include <iostream>
#include <cmath>
#include <vector>
#include <queue>
#include <algorithm>
#include <string>
#include <stack>
#include <set>
#include <map>
#define pii pair <int,int>
#define vec vector
using namespace std;
using ll = long long;
using ld = long double;
using db = double;
void cv(vector <int> &v){
    for (auto x: v) cout<<x<<' ';
    cout<<"\n";
}

void cvl(vector <ll> &v){
    for (auto x: v) cout<<x<<' ';
    cout<<"\n";
}


void cvv(vector <vector <int> > &v){
    for (auto x: v) cv(x);
    cout<<"\n";
}

void cvb(vector <bool> v){
    for (bool x: v) cout<<x<<' ';
    cout<<"\n";
}

void cvs(vector <string>  v){
    for (auto a: v){
        cout<<a<<"\n";
    }
}


//vol - volume, wei - weight

vector <int> par, vol, wei;


struct ed{
    int fr, to, w;
};

vector <ed> G;

bool cmp(ed a, ed b){
    return a.w < b.w;
}

//get_leader
int lead(int v){
    if (par[v] == -1){
        return v;
    }
    else {
        int fth = lead(par[v]);//father
        par[v] = fth;
        return fth;
    }
}


void unite(ed x){
    int a = x.fr, b = x.to , w = x.w;
    int lda = lead(a), ldb = lead(b);
    if (lda == ldb){
        return;
    }
    if (vol[lda] < vol[ldb]){
        swap(lda,ldb);
    }
    par[ldb] = lda;
    vol[lda] += vol[ldb];
    wei[lda] += wei[ldb] + w;
}

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int n,m;
    cin>>n>>m;
    par.assign(n,-1);
    vol.assign(n, 1);
    wei.assign(n, 0);
    G.resize(m);
    for (int i = 0; i < m;++i){
        int a,b,c;
        cin>>a>>b>>c;
        a--;
        b--;
        ed x = {a,b,c};
        G[i] = x;
    }
    sort(G.begin(), G.end(), cmp);
    for (int i = 0; i < m;++i){
        unite(G[i]);
    }
    int god = lead(0);
    cout<<wei[god];
}