[Leetcode] Sort Colors

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.

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

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    void sortColors(int A[], int n) {
        int i = 0;
        int j = 0;
        int k = n-1;
        while(i <= k)
        {
            if (A[i] == 0)
            {
                //swap 0 with the first 1 so that all 0s are before 1s
                swap(A[i], A[j]);
                i++;
                j++;
            }
            else if (A[i] == 1)
            {
                //do nothing if it is 1
                i++;
            }
            else
            {
                //swap 2 with the last element which is not 2
                //note A[k] could be 2 as well so we should not move i forward
                swap(A[i], A[k]);
                k--;
            }
        }
    }