LeetCode 280. Wiggle Sort

原题链接在这里：https://leetcode.com/problems/wiggle-sort/

题目：

Given an unsorted array nums, reorder it in-place such that nums[0] <= nums[1] >= nums[2] <= nums[3]....

Example:

Input: nums = [3,5,2,1,6,4]
Output: One possible answer is [3,5,1,6,2,4]

题解：

当 i 是奇数时，若nums[i] < nums[i-1], 互换。

当 i 是偶数时，若nums[i] > nums[i-1], 互换。

Time Complexity: O(n). Space: O(1).

AC Java:

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

跟上Wiggle Sort II.

类似Rearrange Array Elements by Sign.