Thank you :)

You're right - I focused on passing test cases.
I've just made new solution.
I think it is good idea to suggest the kata author to add test case with this type of input.

Thanks for feedback :) I will pay more attention to efficiency in next solutions :)

My solution is similar, but without sum :)
https://www.codewars.com/kata/reviews/58fe105fbd77cf1487000720/groups/58fe1a41b85eaac2d2000ab2

Thanks a lot! It was really helpful! I have learned a new thing again.