Wiggle Sort

Given an unsorted array nums, reorder it in-place such that nums[0] <= nums[1] >= nums[2] <= nums[3].... For example, given nums = [3, 5, 2, 1, 6, 4], one possible answer is [1, 6, 2, 5, 3, 4].

• Time: O(n)
• Space: O(1)

public void wiggleSort(int[] nums) {
    if (nums == null || nums.length <= 1) return;
    for (int i = 0; i < nums.length - 1; i++) {
        if (i % 2 == 0) {
            if (nums[i] > nums[i + 1]) {
                swap(nums, i, i + 1);
            }
        } else {
            if (nums[i] < nums[i + 1]) {
                swap(nums, i, i + 1);
            }
        }
    }
}

private void swap(int[] nums, int i, int j) {
    int temp = nums[i];
    nums[i] = nums[j];
    nums[j] = temp;
}