prim仅20分求调

#include <bits/stdc++.h>
using namespace std;
const int N = 1e5+10;
long long u,v,w,n,k,tot,ans,st;
struct node{
	long long v,w;
	friend bool operator < (node a,node b){
		return a.w > b.w;
	}
};
vector<node>G[N];
priority_queue<node>q;
long long dis[N];
bool vis[N],ok[N];//ok[i]=true表示k里面的数i需要隔开 
int main(){
	cin>>n>>k;
	for(int i = 1; i <= k; i++){
		cin>>u;
		st = u;//随便从一个点开始 
		ok[u] = true;
	} 
	for(int i = 1; i < n; i++){
		cin>>u>>v>>w;
		G[u].push_back({v,w});
		G[v].push_back({u,w});
	}
	for(int i = 0; i < n; i++) dis[i] = 4*1e18;
	//prim 
	dis[st] = 0; q.push({st,0});
	while(!q.empty()){
		node tmp = q.top(); q.pop();
		if(vis[tmp.v]) continue;
		if(ok[tmp.v]) tot++;//隔开敌军的计数 
		vis[tmp.v] = 1; ans += dis[tmp.v];
		if(tot == k) break;
		for(auto i : G[tmp.v])
			if(dis[i.v] > i.w){
				dis[i.v] = i.w;
				q.push({i.v,i.w});
			}
	}
	cout<<ans<<endl; 
	return 0;
}