Submission #1678236

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Source Code Expand

#include <iostream>
#include <vector>
#include <queue>

using namespace std;

int main(void) {
	int N,M,K,temp;
	cin >> N >> M;
	vector< vector<int> > ps(N);
	vector< vector<int> > ls(M);
	for (int i = 0; i < N; ++i) {
		cin >> K;
		for (int j = 0; j < K; ++j) {
			cin >> temp;
			ps[i].push_back(temp-1);
			ls[temp-1].push_back(i);
		}
	}

	vector<bool> spkp(N,false);
	vector<bool> spkl(M,false);
	bool nf = true;
	bool mode = true;
	int pn,ln;
	queue<int> pars,lang;
	pars.push(0);
	while (nf) {
		nf = false;
		if (mode) {
			while (!pars.empty()) {
				pn = pars.front();
				pars.pop();
				for (size_t i = 0; i < ps[pn].size(); ++i) {
					if (!spkl[ps[pn][i]]) {
						nf = true;
						lang.push(ps[pn][i]);
						spkl[ps[pn][i]] = true;
					}
				}
			}
		}
		else {
			while (!lang.empty()) {
				ln = lang.front();
				lang.pop();
				for (size_t i = 0; i < ls[ln].size(); ++i) {
					if (!spkp[ls[ln][i]]) {
						nf = true;
						pars.push(ls[ln][i]);
						spkp[ls[ln][i]] = true;
					}
				}
			}
		}
		mode = !mode;
	}

	bool find = false;
	for (int i = 0; !find && i < N; ++i) {
		if (!spkp[i]) {
			find = true;
		}
	}

	if (find) {
		cout << "NO" << endl;
	}
	else {
		cout << "YES" << endl;
	}

	return 0;
}

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