Day08_Sort Colors.py

# Sort Colors                            Difficulty: Medium



# Given an array nums 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.

# We will use the integers 0, 1, and 2 to represent the color red, white, and blue, respectively.

# You must solve this problem without using the library's sort function.

 

# Example 1:

# Input: nums = [2,0,2,1,1,0]
# Output: [0,0,1,1,2,2]



class Solution:
    def sortColors(self, nums: List[int]) -> None:
        """
        Do not return anything, modify nums in-place instead.
        """

        l, r = 0 , len(nums) - 1
        i = 0

        def swap(i,j):
            tmp = nums[i]
            nums[i] = nums[j]
            nums[j] = tmp

        while i <= r:
            if nums[i] == 0:
                swap(l, i)
                l += 1
            elif nums[i] == 2:
                swap(i, r)
                r -= 1
                i -= 1
            i += 1