leetcode-75 颜色分类

leetcode-75 颜色分类

题目描述：

给定一个包含红色、白色和蓝色，一共 n 个元素的数组，原地对它们进行排序，使得相同颜色的元素相邻，并按照红色、白色、蓝色顺序排列。此题中，我们使用整数 0、 1 和 2 分别表示红色、白色和蓝色。

解法一：感觉很丑

class Solution:
    def sortColors(self, nums: List[int]) -> None:
        """
        Do not return anything, modify nums in-place instead.
        """
        n = len(nums)
        beg,cur,end=0,0,n-1
        while cur<=end and cur<n:
            while beg<n and nums[beg]%3 == 0:
                beg += 1
            while end>0 and nums[end]%3 == 2:
                end -= 1
            if nums[cur] % 3 == 0 and cur >= beg:
                nums[beg], nums[cur] = nums[cur], nums[beg]
                beg += 1
                if nums[cur] % 3 == 2 and cur <= end:
                    nums[end], nums[cur] = nums[cur], nums[end]
                    end -= 1
            if nums[cur] % 3 == 2 and cur <= end:
                nums[end], nums[cur] = nums[cur], nums[end]
                end -= 1
                if nums[cur] % 3 == 0 and cur >= beg:
                    nums[beg], nums[cur] = nums[cur], nums[beg]
                    beg += 1
            cur += 1
        return nums

解法二：

class Solution:
    def sortColors(self, nums: List[int]) -> None:
        """
        Do not return anything, modify nums in-place instead.
        """
        n = len(nums)
        beg,cur,end=0,0,n-1
        while cur <= end:
            if nums[cur] == 0:
                nums[beg],nums[cur] =  nums[cur],nums[beg]
                beg += 1
                cur += 1
            elif nums[cur] == 1:
                cur += 1
            elif nums[cur] == 2:
                nums[end],nums[cur] =  nums[cur],nums[end]
                end -= 1