Submission #7937683

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Source Code Expand

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <string>
#include <sstream>
#include <complex>
#include <vector>
#include <list>
#include <queue>
#include <deque>
#include <stack>
#include <map>
#include <set>
#include <climits>
#include <random>
#include <iomanip>

using namespace std;
using P = pair<int, int>;

typedef long long int ll;

#define EPS (1e-7)
#define INF (1e9)
#define PI (acos(-1))

#define fillInt(xs, x)        \
  for (int i = 0; i < (x); i++) \
    scanf("%d", &xs[i]);
#define fillLong(xs, x)       \
  for (int i = 0; i < (x); i++) \
    scanf("%ld", &xs[i]);
#define fillString(xs, x)       \
  for (int i = 0; i < (x); i++) \
    cin >> xs[i];
#define sortv(xs) sort(xs.begin(), xs.end())
#define sortvdi(xs) sort(xs.begin(), xs.end(), std::greater<long>())
#define lbv(xs, x) lower_bound(xs.begin(), xs.end(), x) - xs.begin()
#define ubv(xs, x) upper_bound(xs.begin(), xs.end(), x) - xs.begin()
#define bs(xs, x) binary_search(xs.begin(), xs.end(), x)

#define rep(i,n) for(auto i=0; i<(n); i++)

const int mod = 1000000007;


struct UnionFind {
    vector<ll> par;

    UnionFind(ll N) : par(N) {
        for(int i = 0; i < N; i++) par[i] = i;
    }

    ll root(ll x) {
        if (par[x] == x) return x;
        return par[x] = root(par[x]);
    }

    void unite(ll x, ll y) {
        ll rx = root(x);
        ll ry = root(y);
        if (rx == ry) return;
        par[rx] = ry;
    }

    bool same(ll x, ll y) {
        int rx = root(x);
        int ry = root(y);
        return rx == ry;
    }
};

int main()
{
  cin.tie(0);
  ios::sync_with_stdio(false);

  int n, m;
  cin >> n >> m;

  set<int> all;
  UnionFind uf(m);

  int f;
  rep(i, n) {
    int k;
    cin >> k;
    int fst;
    cin >> fst;
    all.insert(fst);
    f = fst;
    rep(i, k-1) {
      int snd;
      cin >> snd;
      all.insert(snd);
      uf.unite(fst, snd);
    }
  }

  bool res = true;
  for(int x: all) {
    res = res && uf.same(f, x);
  }

  cout << (res ? "YES" : "NO") << endl;
}

Submission Info

Judge Result