Submission #3222261

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Source Code Expand

#include <cstdio>
#include <iostream>
#include <string>
#include <vector>
#include <sstream>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <typeinfo>
#include <numeric>
#include <functional>
#include <unordered_map>
#include <bitset>


using namespace std;
using ll = long long;
using ull = unsigned long long;

const ll INF = 1e16;
const ll MOD = 1e9 + 7;

#define REP(i, n) for(ll i = 0; i < n; i++)


class unionfind
{
private:
	vector<long long> par;
	vector<long long> rank;
public:
	void init(long long n);
	long long find(long long x);
	void unite(long long x, long long y);
	bool same(long long x, long long y);
};

// 初期化
void unionfind::init(long long n) {
	for (long long i = 0; i < n; i++) {
		par.push_back(i);
		rank.push_back(0);
	}
}

// 木の根を求める
long long unionfind::find(long long x) {
	if (par[x] == x) {
		return x;
	}
	else {
		return par[x] = find(par[x]);
	}
}

// xとyの属する集合を併合
void unionfind::unite(long long x, long long y) {
	x = find(x);
	y = find(y);
	if (x == y)return;

	if (rank[x] < rank[y]) {
		par[x] = y;
	}
	else {
		par[y] = x;
		if (rank[x] == rank[y]) {
			rank[x]++;
		}
	}
}

// xとyが同じ集合に属していたらtrue
bool unionfind::same(long long x, long long y) {
	return find(x) == find(y);
}

int main() {
    ll n, m;
    cin >> n >> m;
    unionfind uni;
    uni.init(n + m);
    REP(i, n){
        ll k;
        cin >> k;
        REP(j, k){
            ll l;
            cin >> l;
            l--;
            uni.unite(i, n + l);
        }
    }
    REP(i, n){
        if(!uni.same(0, i)){
            cout << "NO" << endl;
            return 0;
        }
    }
    cout << "YES" << endl;
}

Submission Info

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