用邻接列表存储图，排序后输出。

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int n, m;
vector<int> adj[500001];
bool visited[500001];

void solve() {
  cin >> n >> m;
  
  for (int i = 1; i <= m; i++) {
    int u, v;
    cin >> u >> v;
    adj[u].push_back(v);
  }
  for (int i = 1; i <= n; i++) {
    sort(adj[i].begin(),adj[i].end());
    for (auto e : adj[i]) {
      cout << e << ' ';
    }
    cout << endl;
    adj[i].clear();
  }
}

int main() {
  int T;
  cin >> T;
  for (int z = 1; z <= T; z++) {
    solve();
  }
  return 0;
}