这就是一个搜索问题，dfs或者bfs均可

#include<iostream>
#include<cstring>
using namespace std;
bool stat[1001][1001];
bool visited[1001];
void dfs(int a, int b, int n, bool& flag)
{
	visited[a] = true;
	if (stat[a][b]) {
		flag = true;
		return;
	}
	for (int i = 0; i <= n && !flag; i++) {
		if (!visited[i] && stat[a][i]) {
			visited[i] = true;
			dfs(i, b, n, flag);
			visited[i] = false;
		}
	}
}
int main()
{
	int maxn = 0; 
	for (int i = 0; i < 1000; i++) {
		for (int j = 0; j < 1000; j++) {
			if (i == j) {
				stat[i][j] = true;
			}
			else {
				stat[i][j] = false;
			}
		}
	}
	
	int N;
	cin >> N;
	for (int itr = 0; itr < N; itr++) {
		int number;
		cin >> number;
		int i;
		cin >> i;
		maxn = i > maxn ? i : maxn;
		for (int itr2 = 2; itr2 < number; itr2++) {
			int j;
			cin >> j;
			stat[i][j] = true;
			maxn = j > maxn ? j : maxn;
		}
	}
	
	for (int itr = 0...