(20 points) Given an array .a2.. .. , an}, a reverse is a pair (ai, as) such that i j but ai aj. Design divide-and-conquer algorithm with a runtime of O(n log n) for computing the number of reverses in the array. Your solution to this question needs to include both a written explanation and a Python implementation of your algorithm, including: (a) Explain how your algorithm works, including pseudocode. b) Implement your algorithm in Python