P1 (20pt): (a) Given two sorted arrays A[1...n] and B[1...n]. Describe an algorithm to find the median element in the union of A and B in O(log n) time. (b) Given two sorted arrays A[1...m] and B[1...n] and an integer k. Describe an algorithm to find the k-th smallest element in the union of A and B (i.e. AUB) in O(log (m + n)) time. (Hint: use your solution in part (a)]