Sort Color

题目描述

Given an array with n objects colored red, white or blue, sort them 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.

解题方法

quick select 模板解决

Solution

class Solution(object):
    def sortColors(self, nums):
        """
        :type nums: List[int]
        :rtype: void Do not return anything, modify nums in-place instead.
        """
        def swap(p1, p2):
            tmp = nums[p2]
            nums[p2] = nums[p1]
            nums[p1] = tmp

        length = len(nums)
        if length == 0:
            return
        left = 0
        right = length - 1
        p = 0
        while p <= right:
            if nums[p] < 1:
                swap(left, p)
                p += 1
                left += 1
            elif nums[p] == 1:
                p += 1
            else:
                swap(right, p)
                right -= 1

Reference