Submission #1678311

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Source Code Expand

#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
vector<bool> used;

void dfs(vector<vector<int> > &g, int v = 0){
  used[v] = true;
  for (int i = 0; i < g[v].size(); i++) {
    int u = g[v][i];
    if(used[u])continue;
    dfs(g, u);
  }
}

int main(){
  int n, m;
  std::cin >> n >> m;
  vector<vector<int> > g(n + m);
  for (int i = 0; i < n; i++) {
    int k;
    std::cin >> k;
    for (int j = 0; j < k; j++) {
      int to;
      std::cin >> to;
      g[i].push_back(--to + n);
      g[to + n].push_back(i);
    }
  }
  used.resize(n + m, false);
  dfs(g);
  std::cout << (all_of(used.begin(), used.begin() + n,[](bool b){return b;})?"YES":"NO") << std::endl;
  return 0;
}

Submission Info

Judge Result