t3 通过90%用例不知道哪里wa了求大佬ddw

#include <unordered_set>
typedef pair<int,int> pii;
class Solution {
public:
    int Length(vector<int>& niuniu, vector<int>& _niumei, vector<vector<int> >& path, int nn) {
        int ans=INT_MAX;
        vector<vector<pii>> edge(nn+1);
        for (vector<int> &i:path)
        {
            edge.at(i.at(0)).push_back({i.at(1),i.at(2)});
            edge.at(i.at(1)).push_back({i.at(0),i.at(2)});
        }
        unordered_set<int> niumei(_niumei.begin(),_niumei.end());
        vector<bool> use(edge.size(),false);
        priority_queue<pii,vector<pii>,greater<pii>> helper;
        for (int i:niuniu)
        {
            use.at(i)=true;
            helper.push({0,i});
        }
        while (!helper.empty())
        {
            pii a=helper.top();
            int value=a.first;
            int x=a.second;
            helper.pop();
            if (niumei.find(x)!=niumei.end())
                return value;
            for (pii &i:edge.at(x))
                if (!use.at(i.first))
                {
                    if (niumei.find(i.first)==niumei.end())
                        use.at(i.first)=true;
                    helper.push({i.second+value,i.first});
                }
        }
        return -1;
    }
};