Thursday Code Puzzler: Intersection of Two Arrays

Thursday is code puzzler day here at DZone. The idea is simple: solve the coding problem as efficiently as you can, in any language or framework that you find suitable.

Note: Even though there really is nothing stopping you from finding a solution to this on the internet, try to keep honest, and come up with your own answer.  It's all about the participation!

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Find The Intersection of Two Arrays

Given two unsorted arrays as input to a function, find what the intersection (i.e. common elements) of these two arrays is. For example, with the arrays {1,3,5,7,9} and {1,2,3,4,5} the result would be {1,3,5}.

For this solution, focus on the efficiency.

Catch up on all our previous puzzlers here.