ARRAY[] = [50, 11, 33, 21, 40, 50, 40, 40, 21]

Write a full and complete implementation of the Quick Sort Algorithm such that the given array gets fully sorted in O(n log2(n)) time complexity overall and O(1) space complexity. Here, n is the length of the list of input integers (array). Your pivot shall always be the last element of any array you consider. We will not be considering any memory used by recursion.