Kruskal

#include<bits/stdc++.h>

using namespace std;
typedef long long int ll;
//#define isvowel(a) (a == 'a' || a == 'e' || a == 'i' || a == 'o' || a == 'u')
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define gcd __gcd
#define getl(s) getline(cin, s);
#define setpre(x) fixed << setprecision(x)
#define mset(a) memset(a, 0, sizeof(a))
#define endl '\n'
const int N=200050,M=1000000007;
const ll INF=1e18+7;
int cha[N],cha_size[N];
int find_cha(int u){
    if(cha[u]==u) return u;
    return cha[u]=find_cha(cha[u]);
}
void European_Union(int u,int v){
    int a,b;
    a=find_cha(u);
    b=find_cha(v);
    if(cha_size[a]<cha_size[b]) swap(a,b);
    cha[b]=a;
    cha_size[a]+=cha_size[b];
    return;
}
int main(){
    ios_base::sync_with_stdio(NULL); cin.tie(nullptr); cout.tie(nullptr);
//    freopen(".inp","r",stdin);
//    freopen(".out","w",stdout);
    int n,m,x,y,z;
    ll sum=0;
    vector<pair<int,pair<int,int> > >gay;
    cin>>n>>m;
    for(int i=1;i<=n;++i){
        cha[i]=i;
        cha_size[i]=1;
    }
    for(int i=0;i<m;++i){
        cin>>x>>y>>z;
        gay.pb(mp(z,mp(x,y)));
    }
    sort(gay.begin(),gay.end());
    for(int i=0;i<m;++i){
        x=gay[i].se.fi;
        y=gay[i].se.se;
        z=gay[i].fi;
        if(find_cha(x)!=find_cha(y)){
            European_Union(x,y);
            sum+=z;
        }
    }
    cout<<sum;
    return 0;
}
/*
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INPUT:                            |
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OUTPUT:                           |
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*/