Why are you iterating over array twice? it seems wastefull

beautiful

yeah, probably

isnt replacing len(arr) with arr better

Doesn't work for None

really enjoying this solution.

It doesn't seem to work properly if the function argument is None, count_positives_sum_negatives(None).

the 1 in front of the for turns the temporary variable into a 1. That's necessary because you want to count one by one and not add the content of the array.

it is necessary otherwise for empty list it will return [0,0] rather than []

Well, both bool([]) and len([]) returns False. "if arr" is a more pythonic way than "if len(arr)"

the len() is unnecessary, and looping through twice is unnecessary

It could be enforced by kata author, but it isn't so you'll get all different type of solutions.

That's clever, I knew there was a way to loop once

Interesting, I wonder if replacing the element in 'pos' with a 1 makes a difference performance-wise

just do if arr