Submission #991796

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Source Code Expand

#include <iostream>
#include <fstream>
#include <set>
#include <map>
#include <string>
#include <vector>
#include <bitset>
#include <algorithm>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <cassert>
#include <queue>

#define mp make_pair
#define pb push_back


typedef long long ll;
typedef long double ld;

using namespace std;

int n, m;
vector<int> eds[220000];
int was[220000];

void dfs1(int v) {
	was[v] = 1;
	for (int u: eds[v])
		if (!was[u])
			dfs1(u);
}

int main() {
	cin >> n >> m;
	for (int i = 0; i < n; ++i) {
		int k;
		cin >> k;
		for (int j = 0; j < k; ++j) {
			int x;
			cin >> x;
			--x;
			eds[i].push_back(x + n);
			eds[x + n].push_back(i);
		}
	}
	dfs1(0);
	for (int i = 0; i < n; ++i)
		if (!was[i]) {
			cout << "NO\n";
			return 0;
		}
	cout << "YES\n";
	return 0;
}

Submission Info

Judge Result