Problem:
Strongly Connected Components

A direced graph is strongly connected if every two nodes are reachable from each other. In a strongly connected component of a directed graph, every two nodes of the component are mutually reachable.

Input

A directed graph G(V, E) and a sequence of queries where each query contains a pair of nodes u and v.

|V| |E|
s0 t0
s1 t1
:
s|E|-1 t|E|-1
Q
u0 v0
u1 v1
:
uQ-1 vQ-1

|V| is the number of nodes and |E| is the number of edges in the graph. The graph nodes are named with the numbers 0, 1,..., |V|-1 respectively.

si and ti represent source and target nodes of i-th edge (directed).

ui and vi represent a pair of nodes given as the i-th query.

Output

For each query, pinrt "1" if the given nodes belong to the same strongly connected component, "0" otherwise.

Constraints

1 ≤ |V| ≤ 10,000

0 ≤ |E| ≤ 30,000

1 ≤ Q ≤ 100,000

Sample Input 1

5 6
0 1
1 0
1 2
2 4
4 3
3 2
4
0 1
0 3
2 3
3 4

Sample Output 1

1
0
1
1

Solution in JAVA (judge verdict: Wrong Answer)


import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collections;
import java.util.NoSuchElementException;

@SuppressWarnings("unchecked")
public class Main {
  private static class Task {
    void solve(FastScanner in, PrintWriter out) {
      int V = in.nextInt(), E = in.nextInt();
      ArrayList<Integer>[] g = new ArrayList[V];
      for (int i = 0; i < V; i++) g[i] = new ArrayList<Integer>();
      for (int i = 0; i < E; i++) {
        int s = in.nextInt(), t = in.nextInt();
        g[s].add(t);
      }

      StronglyConnectedComponents scc = new StronglyConnectedComponents(g);
      int Q = in.nextInt();
      for (int i = 0; i < Q; i++) {
        int u = in.nextInt(), v = in.nextInt();
        if (scc.cmp[u] == scc.cmp[v]) out.println(1);
        else out.println(0);
      }
    }
  }

  static class StronglyConnectedComponents {
    private int V;
    int[] cmp;
    private ArrayList<Integer>[] G;
    private ArrayList<Integer>[] rG;
    boolean[] used;
    private ArrayList<Integer> vs = new ArrayList<Integer>();

    StronglyConnectedComponents(ArrayList<Integer>[] g) {
      this.G = g;
      V = g.length;
      cmp = new int[V];

      rG = new ArrayList[V];
      for (int i = 0; i < V; i++) rG[i] = new ArrayList<Integer>();
      for (int i = 0; i < V; i++) for (int v : g[i]) rG[v].add(i);
      used = new boolean[V];

//      for (int i = 0; i < V; i++) if (!used[i]) dfs(i);
      ArrayDeque<Integer> stack = new ArrayDeque<>();
      for (int i = 0; i < V; i++)
        if (!used[i]) {
          stack.push(i);
          used[i] = true;
          while (!stack.isEmpty()) {
            int v = stack.peek();
            boolean pushed = false;
            for (int j = G[v].size() - 1; j >= 0; --j) {
              int u = G[v].get(j);
              if (!used[u]) {
                stack.push(u);
                used[u] = true;
                pushed = true;
              }
            }
            if (!pushed) {
              stack.pop();
              vs.add(v);
            }
          }
        }
//      for (int i : vs) System.out.print(i + " ");
//      System.out.println();

      used = new boolean[V];
      int k = 0;
      Collections.reverse(vs);
//      for (int i : vs) if (!used[i]) reverseDfs(i, k++);
      for (int i : vs)
        if (!used[i]) {
          stack.push(i);
          used[i] = true;
          cmp[i] = k;
          while (!stack.isEmpty()) {
            int v = stack.peek();
            boolean pushed = false;
            for (int j = rG[v].size() - 1; j >= 0; --j) {
              int u = rG[v].get(j);
              if (!used[u]) {
                used[u] = true;
                cmp[u] = k;
                stack.push(u);
                pushed = true;
              }
            }
            if (!pushed) stack.pop();
          }
          k++;
        }
    }

    private void dfs(int v) {
      used[v] = true;
      for (int u : G[v]) if (!used[u]) dfs(u);
      vs.add(v);
    }

    private void reverseDfs(int v, int k) {
      used[v] = true;
      cmp[v] = k;
      for (int u : rG[v]) if (!used[u]) reverseDfs(u, k);
    }

  }

  // Template
  public static void main(String[] args) {
    OutputStream outputStream = System.out;
    FastScanner in = new FastScanner();
    PrintWriter out = new PrintWriter(outputStream);
    Task solver = new Task();
    solver.solve(in, out);
    out.close();
  }
  private static class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int bufferLength = 0;

    private boolean hasNextByte() {
      if (ptr < bufferLength) {
        return true;
      } else {
        ptr = 0;
        try {
          bufferLength = in.read(buffer);
        } catch (IOException e) {
          e.printStackTrace();
        }
        if (bufferLength <= 0) {
          return false;
        }
      }
      return true;
    }

    private int readByte() {
      if (hasNextByte()) return buffer[ptr++];
      else return -1;
    }

    private static boolean isPrintableChar(int c) {
      return 33 <= c && c <= 126;
    }

    private void skipUnprintable() {
      while (hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;
    }

    boolean hasNext() {
      skipUnprintable();
      return hasNextByte();
    }

    public String next() {
      if (!hasNext()) throw new NoSuchElementException();
      StringBuilder sb = new StringBuilder();
      int b = readByte();
      while (isPrintableChar(b)) {
        sb.appendCodePoint(b);
        b = readByte();
      }
      return sb.toString();
    }

    long nextLong() {
      if (!hasNext()) throw new NoSuchElementException();
      long n = 0;
      boolean minus = false;
      int b = readByte();
      if (b == '-') {
        minus = true;
        b = readByte();
      }
      if (b < '0' || '9' < b) {
        throw new NumberFormatException();
      }
      while (true) {
        if ('0' <= b && b <= '9') {
          n *= 10;
          n += b - '0';
        } else if (b == -1 || !isPrintableChar(b)) {
          return minus ? -n : n;
        } else {
          throw new NumberFormatException();
        }
        b = readByte();
      }
    }

    double nextDouble() {
      return Double.parseDouble(next());
    }

    double[] nextDoubleArray(int n) {
      double[] array = new double[n];
      for (int i = 0; i < n; i++) {
        array[i] = nextDouble();
      }
      return array;
    }

    double[][] nextDoubleMap(int n, int m) {
      double[][] map = new double[n][];
      for (int i = 0; i < n; i++) {
        map[i] = nextDoubleArray(m);
      }
      return map;
    }

    public int nextInt() {
      return (int) nextLong();
    }
  }
}