This is a bit too involved for a whiteboard problem, IMO, but it isn't that hard to create a relatively clean solution: https://gist.github.com/gresrun/602bd53d

This is a bit too involved for a whiteboard problem, IMO, but it isn't that hard to create a relatively clean solution: https://gist.github.com/gresrun/602bd53dad80bb51bb94 https://gist.github.com/gresrun/602bd53dad80bb51bb94