Nope. Not sure why I included them to be honest, as I think the code is more readable without :-)

are brackets necessary?

Might be cheating, but I learned something.

oh, darn yeah i couldn't figure out the short hand for that either. Thanks @wchargin.

Hey at least your code doesn't rely on black magic :)

I am so sad right now, the sad part is I looked in the docs lol. +1 for simplicity.

Oh darn, :( didn't know why I didn't think of inject. +1 for simplicity.

I would've thought the whole point was to avoid using the existing flatten method.
Guess anything goes, as long as it works and is within the constraints.

Nice. I guess I learned something today!

Thanks:).

I knew I should have just used regex, +1 nice and clean :).

I guess that'll teach me to check the docs before going to a lot of trouble. In any case, thanks for the 1UPs guys. :D

Wowzers. That is some serious effort. One one hand I want to commend you and on the other I want to tell you to take a closer look at the standard library. One of the reasons Ruby can be written in such a concise manner is because of it's very powerful and robust standard library. There are methods for everything it seems. Good luck in your journey!

ditto, the parentheses are extra but it reads better then the other solutions.