We have learned that Mergesort sorts an array of n numbers in O$($n log n$)$ time and Binary

Search determines if a given number is present in a sorted array of n numbers in O$($log n$)$ time.

Describe an O$($n log n$)$ time algorithm that takes as input two arrays A and B with n elements

each $($not necessarily sorted$)$ and determines the largest number in B that is not in A$.$ If all

elements of B are in A$,$ then return $$All elements of B are in A$.$

Your algorithm should use mergesort and binary search and should not us