動機

用pointer去塞

Problem

Given an integer array nums, move all the even integers at the beginning of the array followed by all the odd integers.

Return any array that satisfies this condition.

 

Example 1:

Input: nums = [3,1,2,4]Output: [2,4,3,1]Explanation: The outputs [4,2,3,1], [2,4,1,3], and [4,2,1,3] would also be accepted.

Example 2:

Input: nums = [0]Output: [0]

 

Constraints:

    t
  • 1 <= nums.length <= 5000
    • t
  • 0 <= nums[i] <= 5000

Sol

class Solution:
    def sortArrayByParity(self, nums: List[int]) -> List[int]:
        even, odd = 0, len(nums)-1
        
        while even < odd:
            if nums[even] % 2 == 0:
                even += 1
            elif nums[odd] % 2 == 1:
                odd -= 1
            else:
                nums[even], nums[odd] = nums[odd],nums[even]
                even, odd = even+1, odd-1
        return nums