Codeforces Round #626 (Div. 1, based on Moscow Open Olympiad in Informatics)C（二分图，哈希）

把连接了相同左侧点的右侧点合并，对剩余右侧点求gcd。

#define HAVE_STRUCT_TIMESPEC
#include<bits/stdc++.h>
using namespace std;
long long a[500007];
vector<int>edge[500007];
int main(){
    ios::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    int t;
    cin>>t;
    while(t--){
        int n,m;
        cin>>n>>m;
        for(int i=1;i<=n;++i){
            cin>>a[i];
            edge[i].clear();
        }
        for(int i=1;i<=m;++i){
            int u,v;
            cin>>u>>v;
            edge[v].emplace_back(u);
        }
        map<vector<int> ,long long>mp;
        for(int i=1;i<=n;++i){
            if(edge[i].size()>0){
                sort(edge[i].begin(),edge[i].end());
                mp[edge[i]]+=a[i];
            }
        }
        long long ans=0;
        for(auto it:mp){
            ans=__gcd(ans,it.second);
        }
        cout<<ans<<"
";
    }
    return 0;
}