4 (50p) Let us return to our array A = [5, 6, 4, 7, 3, 8, 2,9,1, 10) from problem set 2, which we still want to sort in increasing order. 4a (40p) Run he ap sort by hand on this array, and show in detail in every step of the algorithm what calls to the heap are made and how the array and the heap change. 4b (10 p) Suppose that we build a max-heap from any given array A. Is it true that once the array A has been converted to a correct max-heap, then considering the elements in reverse order (i.e., A[n], A[n 1),..., A[2], A[1]) yields a correct min-heap? Prove this or give a simple counter-example