Wiggle Sort II

LeetCode Q 324 - Wiggle Sort II

Given an unsorted array nums, reorder it such that nums[0] < nums[1] > nums[2] < nums[3]….

Example 1:
Input: nums = [1, 5, 1, 1, 6, 4] ; Output: One possible answer is [1, 4, 1, 5, 1, 6].

Example 2:
Input: nums = [1, 3, 2, 2, 3, 1] ; Output: One possible answer is [2, 3, 1, 3, 1, 2].

Note: You may assume all input has valid answer.

Follow Up: Can you do it in O(n) time and/or in-place with O(1) extra space?

Solution

Code:

public void wiggleSort(int[] nums) {
	
	if (nums == null || nums.length <= 1)
		return;
	
	int[] copy = Arrays.copyOf(nums, nums.length); //(int[])nums.clone();
	
	Arrays.sort(copy);
	
	int mid = (nums.length + 1) / 2;
	
	for (int i = 0, j = mid - 1; j >= 0; i += 2, j--)
		nums[i] = copy[j];
	
	for (int i = 1, j = nums.length - 1; j >= mid; i += 2, j--)
		nums[i] = copy[j];
	
	return;
	
}