刚开始还以为是没加快读的问题，加上以后还是得T.....

Code：

#include<bits/stdc++.h>
#define int long long
#define N 500005
using namespace std;
vector<int> vec[N];
int t,n,m;
int read(){
    int x=0,f=1;char ch=getchar();
    while(!isdigit(ch)){if(ch=='-') f=-1;ch=getchar();}
	while(isdigit(ch)){x=x*10+ch-48;ch=getchar();}
	return x*f;
}
signed main(){
    ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
    cin>>t;
    while(t--){
        n=read();
        m=read();
        for (int i=1;i<=m;i++){
            int u,v;
            u=read();
            v=read();
            vec[u].push_back(v);
        }
        //cout<<"-------------"<<endl;
        for (int i=1;i<=n;i++){
            if (vec[i].size()==0)cout<<endl;
            else{
                sort(vec[i].begin(),vec[i].end());
                for (vector<int>::iterator it=vec[i].begin();it!=vec[i].end();it++){
                    cout<<*it<<" ";
                }
                cout<<endl;
            }
        }
    }
}

求dalao指点！