Color classification (three pointers)

Ricochet: Ricochet

        Given an array nums of n elements red, white, and blue, sort them in-place so that elements of the same color are next to each other in the order red, white, and blue.

We use the integers 0, 1, and 2 to represent red, white, and blue, respectively.

This problem must be solved without using the library's built-in sort function.

Example 1:

Input: nums = [2,0,2,1,1,0]
Output: [0,0,1,1,2,2]

Example 2:

Input: nums = [2,0,1]
Output: [0,1,2]

hint:

n == nums.length
1 <= n <= 300
nums[i] 为 0、1 或 2

Sample code 1: [Three pointers]

class Solution:
    def sortColors(self, nums: List[int]) -> None:
        """
        Do not return anything, modify nums in-place instead.
        """
        def swap(nums, index1, index2):
            nums[index1], nums[index2] = nums[index2], nums[index1]
        size = len(nums)
        zero = 0
        two = size
        i = 0
        while i < two:
            if nums[i] == 0:
                swap(nums, i, zero)
                i += 1
                zero += 1
            elif nums[i] == 1:
                i += 1
            else:
                two -= 1
                swap(nums, i, two)