洛谷日刷2

#include <iostream>
#include <algorithm>
using namespace std;
struct {
    int u,v,w;
    bool operator < (const Edge&a){
        return w<a.w;
    }
}edge[200005];
int fa[5005],n,m;
int ans,eu,ev,cnt;
int find(int x){
    return x==fa[x]? x:find(fa[x]);
}
void kruskal(){
    sort(edge,edge+m);
    for( int i=0;i<m;i++){
        eu=find(edge[i].u); 
        ev=find(edge[i].v);
        if(eu==ev)
            continue;
        ans+=edge[i].w;
        fa[ev]=eu;
        if(++cnt==n-1)
            break;
    }
}
int main(){
    scanf("%d %d",&n,&m);
    for( int i=1;i<=n;i++)
        fa[i]=i;
    for( int i=0;i<m;i++)
        scanf("%d %d %d",&edge[i].u,&edge[i].v,&edge[i].w);
    kruskal();
    printf("%d",ans);
    return 0;
}