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?

class Solution {
 public void wiggleSort(int[] nums) {
    if (nums.length <= 1) {
            return;
        }
        Arrays.sort(nums);
        int mid = 0;
        if (nums.length % 2 == 0) {
            mid = nums.length / 2;
        } else {
            mid = nums.length / 2 + 1;
        }
        int left = mid - 1;
        int right = nums.length - 1;

        int[] ans = new int[nums.length];

        int even = 0;
        while (left >= 0) {

            ans[even] = nums[left];
            left--;
            even = even + 2;
        }
        int odd = 1;
        while (right >= mid) {
            ans[odd] = nums[right];
            right--;
            odd = odd + 2;
        }
        System.arraycopy(ans, 0, nums, 0, nums.length);
    }
}