75. 颜色分类

https://leetcode.cn/problems/sort-colors/submissions/
标签
需要注意的点

1. 两种指针方式，一种是取0和1，另一种是取0,2
2. nums[i] 需要进行交换
3. 注释写一些test case
4. 解法1，参考https://www.bilibili.com/video/BV1Jg411M7Lp?spm_id_from=333.337.search-card.all.click&vd_source=e8e1b6de93e68d8ce8ab44afe5802a40

class Solution:
    def sortColors(self, nums: List[int]) -> None:
        """
        Do not return anything, modify nums in-place instead.
        """
        '''
        2,0,2,1,1,0
        ,0,1,1,2,2,0
        '''
        p0,p2 = 0, len(nums)-1
        i = 0
        while i <= p2:
            if nums[i] == 0:
                self.swap(nums, i, p0)
                i+=1
                p0+=1
            elif nums[i] == 1:
                i+=1
            else:
                self.swap(nums,i, p2)
                p2 -=1
    def swap(self, nums, index1, index2):
        nums[index1],nums[index2] = nums[index2],nums[index1]

class Solution:
    def sortColors(self, nums: List[int]) -> None:
        """
        Do not return anything, modify nums in-place instead.
        """
        '''
            1,0,1,2,0
            0,0,0,1,2,0
        '''
        size = len(nums)
        p0, p1 = 0, 0
        for i in range(size):
            if nums[i] == 1:
                nums[i], nums[p1] = nums[p1], nums[i]
                p1 += 1
            if nums[i] == 0:
                nums[i], nums[p0] = nums[p0], nums[i]
                if p0 < p1:
                    nums[i], nums[p1] = nums[p1], nums[i]
                p0 += 1
                p1 += 1