Company Queries II

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class CompanyQueriesII {
    public static void main(String[] args) {
        FastScanner input = new FastScanner(System.in);
        int n = input.nextInt();
        int q = input.nextInt();

        int[] employeeBosses = new int[n+1];
        for (int i = 2; i <=n; i++){
            employeeBosses[i] = input.nextInt();
        }

        int LOG = 1;
        while ((1 << LOG) <= n) {
            LOG++;
        }

        int[][] up = new int[n + 1][LOG];
        int[] depth = new int[n + 1];

        for (int i = 1; i <= n; i++) {
            up[i][0] = employeeBosses[i];

            if (i > 1) {
                depth[i] = depth[employeeBosses[i]] + 1;
            }
        }

        for (int j = 1; j < LOG; j++) {
            for (int i = 1; i <= n; i++) {
                up[i][j] = up[up[i][j - 1]][j - 1];
            }
        }

        StringBuilder output = new StringBuilder();

        while (q-- > 0) {
            int a = input.nextInt();
            int b = input.nextInt();

            if (depth[a] < depth[b]) {
                int temp = a;
                a = b;
                b = temp;
            }

            int diff = depth[a] - depth[b];

            for (int j = 0; j < LOG; j++) {
                if ((diff & (1 << j)) != 0) {
                    a = up[a][j];
                }
            }

            if (a == b) {
                output.append(a).append('\n');
                continue;
            }

            for (int j = LOG - 1; j >= 0; j--) {
                if (up[a][j] != up[b][j]) {
                    a = up[a][j];
                    b = up[b][j];
                }
            }

            output.append(up[a][0]).append('\n');
        }

        System.out.print(output);

    }

    static class FastScanner { //static class fastScanner
    private BufferedReader reader = null;
    private StringTokenizer tokenizer = null;

    public FastScanner(InputStream in) {
        reader = new BufferedReader(new InputStreamReader(in));
        tokenizer = null;
    }

    public String next() {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken();
    }

    public String nextLine() {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                return reader.readLine();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }

        return tokenizer.nextToken("\n");
    }

    public long nextLong() {
        return Long.parseLong(next());
    }

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

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

    public int[] nextIntArray(int n) {
        int[] a = new int[n];
        for (int i = 0; i < n; i++)
            a[i] = nextInt();
        return a;
    }

    public long[] nextLongArray(int n) {
        long[] a = new long[n];
        for (int i = 0; i < n; i++)
            a[i] = nextLong();
        return a;
    }
}
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: TIME LIMIT EXCEEDED