Leetcode daily question - 324 Swing sort II

subject

Give you an array of integers nums, Rearrange it into nums[0] < nums[1] > nums[2] < nums[3]… The order of .

You can assume that all input arrays can get results that meet the requirements of the topic .

Example

Example 1：

Input ：nums = [1,5,1,1,6,4]
Output ：[1,6,1,5,1,4]
explain ：[1,4,1,5,1,6] It is also the result that meets the requirements of the topic , It can be accepted by the problem determination program .

Example 2：

Input ：nums = [1,3,2,2,3,1]
Output ：[2,3,1,3,1,2]

Ideas

The title means ： Converts the given array to an array with size number intervals , This question is decimal — Large number — decimal — Form of large numbers .
Here you can use interleaved sorting ： Sort the array first , It is divided into large part and decimal part , Then interleave and sort . Order of attention , for example [1,3,4,4,4,7] This array , By interleaving in descending order [4,7,3,4,1,4]. If you arrange them in order , You will get [1,4,3,4,4,7] Not meeting the requirements . This is because we want to put the maximum number of the decimal part on the side , In this way, only the maximum number close to a large number part .

Answer key

class Solution:
    def wiggleSort(self, nums: List[int]) -> None:
        """ Do not return anything, modify nums in-place instead. """
        nums.sort()
        half = len(nums[::2])
        nums[::2], nums[1::2] = nums[:half][::-1], nums[half:][::-1]