Finding median of large set of numbers too big to fit into memory

Question

I was asked this question in an interview recently.

There are N numbers, too many to fit into memory. They are split across k database tables (unsorted), each of whi

Answer 1

Have a look at the "Median of Medians" algorithm in this wikipedia article.

Related question: Median-of-medians in Java.

Explanation: http://www.ics.uci.edu/~eppstein/161/960130.html