code wars is ruined by the 13 to 20 demographic

why not using lambda and join atp? (i don't know if it's actually possible, but i think it should be just by looking at how you used the return)

I like the logic behind your solution. Very similar to mine

im amazed by these one line solutions!
nicely done.

this is not performant. it goes over list multiple times

Copy that. Thank you!

not usually best practice, in real life strive for readibility while being able to make your code shorter

I keep forgetting I don't need to make new variables for everything and it can all usually fit inside a return statement. Unsure at my level if that is the best practice, but the fewer lines of code is what I'm currently striving for as I learn.

This is a smart one.

No but tests guarantee that there is ever only two different numbers, one of them unique.

It would indeed.

That's what I've done.

Guys will that work if there is two different uniq numbers?

same hahahaha

How's that going to return [0] if arr is blank though?