LeetCode 324. Wiggle Sort II

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

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

题目大意:给一个数组,按照nums[0] < nums[1] > nums[2] < nums[3]…的顺序重排序数组~

分析:先给数组排序,然后拷贝一份一样的数组arr。然后p指针从数组中间开始向前,q指针从数组最后一位开始向前,依次赋值给nums[i]和nums[j]——其中i是偶数下标,j是奇数下标~