Problem 2. Given an array of numbers X- {x1, x2, , xn), an exchanged pair in X is a pair (xi, xj) such that i xj. Note that an element x, can be part of up to n 1 exchanged pairs, and that the maximal possible number of exchanged pairs in X is n(n - 1)/2, which is achieved if the array is sorted in descending order. Give a divide-and-conquer algorithm that counts the number of exchanged pairs in X in O(n log n time