Problem

Given an unsorted array nums, reorder it in-place such that

nums[0] <= nums[1] >= nums[2] <= nums[3]....

Please complete the problem in-place.

Example
Given nums = [3, 5, 2, 1, 6, 4], one possible answer is [1, 6, 2, 5, 3, 4].

思路

• 只有两种情况, 数a 和 b, a <= b 或者 b <= a
• a <= b <= c, 调换 b 和 c. 那么肯定满足 a <= c >= b

    public void wiggleSort(int[] nums) {
        if (nums == null || nums.length == 0) {
            return;
        }

        for (int i = 0; i < nums.length - 1; i++) {
            if (i % 2 == 0 && nums[i] <= nums[i + 1]
                || i % 2 != 0 && nums[i] >= nums[i + 1]) {
                    continue;
            }
            int temp = nums[i];
            nums[i] = nums[i + 1];
            nums[i + 1] = temp;
        }