Submission #128232

#	Time	Username	Problem	Language	Result	Execution time	Memory
128232		zeyad49	Pipes (CEOI15_pipes)	Java	10 / 100	186 ms	65540 KiB

pipes

import java.io.*;
import java.util.*;

public class pipes {

	static ArrayList<Integer>[] adjList;
	static int[] dfs_low, dfs_num, parent;
	static int V, counter;
	static PrintWriter out = new PrintWriter(System.out);
	static int [][]cnt;
	public static void main(String[] args) throws IOException {
		Scanner sc = new Scanner();
		V = sc.nextInt();
		cnt=new int [V][V];
		adjList = new ArrayList[V];
		for (int i = 0; i < V; i++)
			adjList[i] = new ArrayList();
		int m = sc.nextInt();
		while (m-- > 0) {
			int u = sc.nextInt() - 1, v = sc.nextInt() - 1;
			adjList[u].add(v);
			adjList[v].add(u);
			cnt[u][v]++;
			cnt[v][u]++;
			
		}
		dfs_low = new int[V];
		dfs_num = new int[V];
		parent = new int[V];
		findArtPointsAndBridges();
		out.close();

	}

	static void findArtPointsAndBridges() // O(V + E)
	{
		for (int i = 0; i < V; ++i)
			if (dfs_num[i] == 0) {

				dfs(i);

			}
	}

	static void dfs(int u) {
		dfs_num[u] = dfs_low[u] = ++counter;
		for (int v : adjList[u])
			if (dfs_num[v] == 0) {
				parent[v] = u;

				dfs(v);

				if (dfs_low[v] > dfs_num[u] && cnt[u][v]==1)
					out.printf("%d %d%n", u + 1, v + 1);
				dfs_low[u] = Math.min(dfs_low[v], dfs_low[u]);
			} else if (parent[u] != v)
				dfs_low[u] = Math.min(dfs_low[u], dfs_num[v]);
	}

	static class Scanner {
		BufferedReader br;
		StringTokenizer st;

		Scanner() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}

		Scanner(String fileName) throws FileNotFoundException {
			br = new BufferedReader(new FileReader(fileName));
		}

		String next() throws IOException {
			while (st == null || !st.hasMoreTokens())
				st = new StringTokenizer(br.readLine());
			return st.nextToken();
		}

		String nextLine() throws IOException {
			return br.readLine();
		}

		int nextInt() throws IOException {
			return Integer.parseInt(next());
		}

		long nextLong() throws NumberFormatException, IOException {
			return Long.parseLong(next());
		}

		double nextDouble() throws NumberFormatException, IOException {
			return Double.parseDouble(next());
		}

		boolean ready() throws IOException {
			return br.ready();
		}

	}

}

Compilation message (stderr)

Note: pipes.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

• Subtask 1: 10 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 10
• Subtask 4: 0 / 10
• Subtask 5: 0 / 10
• Subtask 6: 0 / 10
• Subtask 7: 0 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10
• Subtask 10: 0 / 10