Submission #992714

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;

#define REP(i, s, n) for(int i = s; i < n; ++i)
#define rep(i, n)		 REP(i, 0, n)
#define SORT(c)			 sort((c).begin(), (c).end())
#define IINF	INT_MAX
#define LLINF LLONG_MAX

typedef long long				ll;
typedef pair <int, int> ii;

#define DEBUG false

int main() {
		ll n, m;
		cin >> n >> m;

		vector <bool> check(n);
		vector <bool> used(m);
		map <ll, vector <int> > mp;

		ll k;
		vector <vector<int> > list(n);
		rep(j, n) {
				cin >> k;
				rep(i, k) {
						int tmp;
						cin >> tmp;
            list[j].push_back(tmp);
						mp[tmp].push_back(j);
				}
		}

		queue <int> qu;
		check[0] = true;
		rep(i, list[0].size()) {
				qu.push(list[0][i]);
		}

		while(!qu.empty()) {
				int num = qu.front(); qu.pop();
        if(DEBUG) cout << "num:"<<num<<endl;
				if(used[num]) continue;
        used[num] = true;

        vector<int> vv = mp[num];
        rep(i, vv.size()){
          int id = vv[i];
          if(!check[id]){
            rep(j, list[id].size()){
              if(!used[list[id][j]]) qu.push(list[id][j]);
            }
          }
          check[id] = true;
        }
		}

    bool ans = true;
    rep(i, n) if(!check[i]) ans = false;

    if(DEBUG) rep(i, n) cout << check[i] <<endl;

    if(ans) cout << "YES" <<endl;
    else cout <<"NO" <<endl;

		return 0;
}

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