Tests are limited to within Int range, which is specified to be at least 29 bits IIRC.

That fixed test added. Solution should be invalidated now.

It will fail at the specific part where user code fails, though, so I don't think that's too much of a problem.

Yeah this was due to hidden tab characters, fixed now.

I agree. String ++ Nothing = Nothing or String? Both solutions seem to be possible. I guess this is gilgamec's trouble.

Well, after I read in description, that efficiency is important, I first thought of this. If it had not worked, I would have tried introselect :D

As far as I know, the Θ(n) solution has a very big constant. I'm not entirely sure how big it is but it may very well not be faster for any number of elements that can be tested on Codewars.

I tried to do it in Θ(n) :/

fixed! thanks :)

It's a part of the task.

It's a part of the task.

Good idea, I added a note

It's not clear what you want to do with Nothing arguments.

You should either specify the order you want the products in, or allow any ordering in the answer.