【模板】最小生成树

#include<algorithm>
using namespace std;
int n,m,f[5005],ans,cnt,fx,fy;
struct  {
	int x,y,z;
} a[200005];
bool cmp(node x,node y) {
	return x.z<y.z;
}
int find(int k) {
	if(f[k]==k)return k;
	return f[k]=find(f[k]);
}
int main() {
	scanf("%d%d",&n,&m);
	for(int i=1; i<=n; i++)f[i]=i;//初始化并查集 
	for(int i=1; i<=m; i++) {
		scanf("%d%d%d",&a[i].x,&a[i].y,&a[i].z);
	}
	sort(a+1,a+1+m,cmp);//按边权升序排序 
	for(int i=1; i<=m; i++) {
		fx=find(a[i].x);fy=find(a[i].y);
		if(fx==fy)continue;//如果已相连则不再连 
		f[fy]=fx;
		ans+=a[i].z;
		cnt++;
		if(cnt==n-1)break;
	}
	printf("%d",ans);
}