If you had an array of 1 million values and you had to remove duplicates

http://www.quora.com/Whats-the-best-way-to-delete-duplicates-from-a-sorted-array-in-math-O-log-N-math-time-and-math-O-1-math-space

https://mtatar.wordpress.com/2013/02/26/how-would-you-quickly-detect-duplicates-in-an-array-of-10-million-random-64-bit-integers/