LeetCode 75. Sort Colors--Python解法

题目地址：Sort Colors - LeetCode

---

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.

Example:

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

Follow up:

• A rather straight forward solution is a two-pass algorithm using counting sort.
  First, iterate the array counting number of 0’s, 1’s, and 2’s, then overwrite array with total number of 0’s, then 1’s and followed by 2’s.
• Could you come up with a one-pass algorithm using only constant space?

---

这道题目很简单，就是排序

Python解法如下：

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

太简单了，其他解法就不写了。