Submission #1986427

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Source Code Expand

class UnionFind {
	private int[] table;
	private int[] rank;
	
	public UnionFind(int size) {
		this.table = new int[size];
		this.rank = new int[size];
		for (int i = 0; i < size; i ++) {
			this.table[i] = i;
			this.rank[i] = 1;
		}
	}

	public boolean isSame(int node1, int node2) {
		return find(node1) == find(node2);
	}

	public int find(int node) {
		if (table[node] == node) {
			return node;
		} else {
			return table[node] = find(table[node]);
		}
	}

	public void union(int node1, int node2) {
		int root1 = find(node1);
		int root2 = find(node2);
		
		if (rank[root1] < rank[root2]) {
			table[root1] = root2;
		} else if (rank[root1] > rank[root2]) {
			table[root2] = root1;
		} else if (root1 != root2) {
			table[root2] = root1;
			rank[root1] ++;
		}
	}
}
public class Main {

	private static void solve() {
		int n = ni();
		int m = ni();
		
		UnionFind uf = new UnionFind(n + m);
		for (int i = 0; i < n; i ++) {
			int k = ni();
			for (int j = 0; j < k; j ++) {
				uf.union(i, n + ni() - 1);
			}
		}
		int root = uf.find(0);
		for (int i = 0; i < n; i ++) {
			if (uf.find(i) != root) {
				System.out.println("NO");
				return;
			}
		}
		System.out.println("YES");
	}

	public static void main(String[] args) {
		new Thread(null, new Runnable() {
			@Override
			public void run() {
				long start = System.currentTimeMillis();
				String debug = args.length > 0 ? args[0] : null;
				if (debug != null) {
					try {
						is = java.nio.file.Files.newInputStream(java.nio.file.Paths.get(debug));
					} catch (Exception e) {
						throw new RuntimeException(e);
					}
				}
				reader = new java.io.BufferedReader(new java.io.InputStreamReader(is), 32768);
				solve();
				out.flush();
				tr((System.currentTimeMillis() - start) + "ms");
			}
		}, "", 64000000).start();
	}

	private static java.io.InputStream is = System.in;
	private static java.io.PrintWriter out = new java.io.PrintWriter(System.out);
	private static java.util.StringTokenizer tokenizer = null;
	private static java.io.BufferedReader reader;

	public static String next() {
		while (tokenizer == null || !tokenizer.hasMoreTokens()) {
			try {
				tokenizer = new java.util.StringTokenizer(reader.readLine());
			} catch (Exception e) {
				throw new RuntimeException(e);
			}
		}
		return tokenizer.nextToken();
	}

	private static double nd() {
		return Double.parseDouble(next());
	}

	private static long nl() {
		return Long.parseLong(next());
	}

	private static int[] na(int n) {
		int[] a = new int[n];
		for (int i = 0; i < n; i++)
			a[i] = ni();
		return a;
	}

	private static char[] ns() {
		return next().toCharArray();
	}

	private static long[] nal(int n) {
		long[] a = new long[n];
		for (int i = 0; i < n; i++)
			a[i] = nl();
		return a;
	}

	private static int[][] ntable(int n, int m) {
		int[][] table = new int[n][m];
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < m; j++) {
				table[i][j] = ni();
			}
		}
		return table;
	}

	private static int[][] nlist(int n, int m) {
		int[][] table = new int[m][n];
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < m; j++) {
				table[j][i] = ni();
			}
		}
		return table;
	}

	private static int ni() {
		return Integer.parseInt(next());
	}

	private static void tr(Object... o) {
		if (is != System.in)
			System.out.println(java.util.Arrays.deepToString(o));
	}
}

Submission Info

Judge Result