I know it's tongue in cheek, but shouldn't you use a more difficult example? Inverting a binary tree is trivial. (Example solution: https://leetcode.com/problems/invert-binary-tree/discuss/111...)

It's a reference to the engineer that created homebrew but failed a google interview where they asked him that question: https://twitter.com/mxcl/status/608682016205344768?s=20

Not worth working there anyways.