MaximumMinimumArrangement.java

package com.interview.array;

/**
 * Date 04/16/2016
 * @author Tushar Roy
 *
 * Given a sorted array of positive integers, rearrange the array alternately i.e first element should be maximum value,
 * second minimum value, third second max, fourth second min and so on.
 *
 * Time complexity O(n)
 * Space complexity O(1)
 *
 * http://www.geeksforgeeks.org/rearrange-array-maximum-minimum-form/
 */
public class MaximumMinimumArrangement {

    public void rearrange(int[] input) {
        for (int i = 0; i < input.length; i++) {
            int t = input[i];
            if (t < 0) {
                continue;
            }
            int i1 = i;
            while (true) {
                int j = i1 < input.length/2 ? 2 * i1 + 1 : (input.length - 1 - i1) * 2;
                if (j == i1) {
                    break;
                }
                if (input[j] < 0) {
                    break;
                }
                int t1 = input[j];
                input[j] = -t;
                t = t1;
                i1 = j;
            }
        }

        for (int i = 0; i < input.length; i++) {
            input[i] = Math.abs(input[i]);
        }
    }
}