An algorithm to find the nth largest number in two arrays of size n

Question

I have this question:

Given two sorted lists (stored in arrays) of size n, find an O(log n) algorithm that computes the nth largest element in the union

Answer 1

Evgeny Kluev gives a better answer - mine was O(n log n) since i didn't think about them as being sorted.

what i can add is give you a link to a very nice video explaining binary search, courtesy of MIT:

https://www.youtube.com/watch?v=UNHQ7CRsEtU