@[PartiallyCorrect](/user/571348)
1. 你没开 long long
2. 判断合并条件写错了
AC 代码：
```cpp
#include<bits/stdc++.h>
using namespace std;
#define int long long
const int N=200005;
int fa[N];
bool used[N];
int find(int x){
return fa[x]==x?x:fa[x]=find(fa[x]);
}
void unionn(int x,int y){
x=find(x);y=find(y);
fa[x]=y;
}
struct node{
int from,to,val;
bool operator<(const node& t)const{
return val>t.val;
}
};
vector<node> edge;
signed main(){
int n, k;
int s = 0;
cin >> n >> k;
for(int i = 1 ; i <= k ; i ++)
{
int x;
cin >> x;
used[x] = true;
}
for(int i = 1 ; i < n ; i ++)
{
int x, y, z;
cin >> x >> y >> z;
edge.push_back({x, y, z});
//edge.push_back({y, x, z});
s += z;
}
sort(edge.begin(),edge.end());
int ans=0,cnt=0;
for(int i=1;i<=n;i++)
fa[i]=i;
for(int i=0;i<edge.size();i++){
int x=find(edge[i].from);
int y=find(edge[i].to);
if(used[x]&&used[y])
continue;
fa[x]=y;
ans+=edge[i].val;
if(used[x]) used[y]=true;
else if(used[y]) used[x]=true;
}
cout<<s - ans;
return 0;
}
```
有用求关~
by UncleSam_Died @ 2024-01-30 20:07:00