最小生成树

// luogu-judger-enable-o2
#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<cstdlib>
#include<algorithm>
#include<ctime>
using namespace std;
const int N=100005;
int n,m,u1,v1,Cnt,fa[N],ans;
struct Node{
    int u,v,w;
}Edge[N*2];
bool cmp(Node a,Node b){
    return a.w<b.w;
}
int find(int x){
    if(fa[x]!=x){
        fa[x]=find(fa[x]);
    }
    return fa[x];
}
void kruskal(){
    sort(Edge,Edge+m,cmp);
    for(int i=0;i<m;i++){
        u1=find(Edge[i].u);
        v1=find(Edge[i].v);
        if(u1==v1){
            continue;
        }
        ans+=Edge[i].w;
        fa[v1]=u1;
        Cnt++;
        if(Cnt==n-1){
            break;
        }
    }
}
int main(){
    scanf("%d%d",&n,&m);
    for(int i=0;i<m;i++){
        scanf("%d%d%d",&Edge[i].u,&Edge[i].v,&Edge[i].w);
    }
    for(int i=1;i<=n;i++){
        fa[i]=i;
    }
    kruskal();
    printf("%d\n",ans);
    return 0;
}