C++(clang++ 11.0.1) 解法, 执行用时: 98ms, 内存消耗: 10732K, 提交时间: 2022-08-30 22:12:31

#include <bits/stdc++.h>
using namespace std;
#define ios_fast ios::sync_with_stdio(0), cin.tie(0), cout.tie(0)

int n;
vector<set<int>> L, R;

int main() {
  ios_fast;
  cin >> n;
  L.assign(n + 1, {});
  R.assign(n + 1, {});
  for (int i = 1, m, x; i <= n; i++) {
    cin >> m;
    while (m--) {
      cin >> x;
      L[i].insert(x), R[x].insert(i);
    }
  }
  for (int i = 1, x; i <= n; i++) {
    cin >> x;
  }
  for (int i = 1; i <= n; i++) {
    if (R[i].size() == 1) {
      L[*R[i].begin()].clear();
      L[*R[i].begin()].insert(i);
    }
  }
  for (int t = 1; t > 0; t--) {
    for (int i = 1; i <= n; i++) {
      if (L[i].size() == 1) {
        int j = *L[i].begin();
        if (R[j].size() == 1) continue;
        for (const int& v : R[j])
          if (v != i) L[v].erase(j);
      }
    }
  }
  for (int i = 1; i <= n; i++) {
      cout << L[i].size() << " ";
    for (const int& v : L[i]) cout << v << " ";
    cout << '\n';
  }
}