It works well, but it must be refactored as it's really difficult to follow the logic let alone maintain this solution.

I really liked your use of reduce. I'm happy I looked it up. Such a handy little function

checks for negative numbers

Yo this is beautiful

Excellent

This is a thing of beauty. I've grown as a programmer seeing this brilliant algorithm.

thanks for the explanation!

It's interesting, but hard to understand with a single look.

I mean it works as you say. Plus, this is common behavior. C and C++ return the same. You'd be adding extra code to handle something that is internally handled for you.

I'm sure it's short but sooo unreadable.