[Leetcode] Sort Colors

Given an array with n objects colored red, white or blue, sort them so, objects of the same color is Adjacen T, with the colors in the order red, white and blue.

Here, we'll use the integers 0, 1, and 2 to represent the color red, white, and blue respectively.

Note:
You is not a suppose to use the library's sort function for this problem.

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?

Use-pointers pointing at start and end, these, pointers is used to indicate the boundary of 0, 1, 2. While iterating, the current item was swapped to corresponding boundary position.

1 defsortcolors (nums):2left =03right = Len (nums)-14i =05      whileI <=Right :6         ifNums[i] = =0:7Nums[i], nums[left] =Nums[left], Nums[i]8i + = 19Left + = 1Ten         elifNums[i] = = 1: Onei + = 1 A         elifNums[i] = = 2: -Nums[i], nums[right] =Nums[right], Nums[i] -Right-= 1

[Leetcode] Sort Colors