题目
Given an array with n objects colored red, white or blue, sort them in-place so that objects of the same color are adjacent, with the colors in the order red, white and blue.
Here, we will use the integers 0, 1, and 2 to represent the color red, white, and blue respectively.
Note: You are not suppose to use the library’s sort function for this problem.
解题思路
维护三个指针，p0指向0的最右边，p2指向2的最左边，p1指向当前位置，如果p1指向的是0和p0交换，是2和p2交换，是1则继续
代码
class Solution:
def sortColors(self, nums: List[int]) -> None:
"""
Do not return anything, modify nums in-place instead.
"""
p0, p1, p2 = 0, 0, len(nums) - 1
while p1 <= p2:
if nums[p1] == 0:
nums[p0], nums[p1] = nums[p1], nums[p0]
p0 += 1
p1 += 1
elif nums[p1] == 2:
nums[p1], nums[p2] = nums[p2], nums[p1]
p2 -= 1
else:
p1 += 1
