Submission #5017436

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Source Code Expand

#include <bits/stdc++.h>

using std::cin;
using std::cout;

const int MAXN = 2e5 + 10;

int f[MAXN];

int find(int x){return x==f[x]?x:f[x]=find(f[x]);}
void unite(int x, int y){
    int fx=find(x),fy=find(y);
    if (fx==fy)return;
    f[fx]=fy;
}
void solve() {
    int n, m;
    cin >> n >> m ;
    for (int i = 1; i <= m + n; ++i) f[i] = i;
    for (int i = 1, K; i <= n; ++i) {
        cin >> K;
        for (int j = 0, x; j < K; ++j) {
            cin >> x;
            unite(x, i + m);
            // cout << x << i + m << "\n";
        }
    }
    for (int i = 1; i <= n; ++i) {
        if (find(m + i) == find(m + 1)) continue;
        cout << "NO\n";
        return;
    }
    cout << "YES\n";
}

int main() {
    std::ios::sync_with_stdio(false);
    cin.tie(0);
#ifdef trote
    freopen("../1.txt", "r", stdin);
    freopen("../out.txt", "w", stdout);
#endif
    solve();
    return 0;
}

Submission Info

Judge Result