The best! How it worksw? :-D

seriously it is works ;)

Hi!
So, what if we have array {1,1,-1}? It will loop but will not get back into "0" position. Would be a nice test case :)

Let us hope the efficiency will become OK with some future optimizing Java compiler.

A very enlightening kata. Thank you sensei!

Enjoyed the puzzle! Thanks!

Thanks!

Liked this kata: it has no "swift and clever" solution, had to work hard and elaborate all cases.

O(2^n) as it seems to me, in a really-really worst case:
when at each step you have to explore both trees to full depth (or near full).

A very clever and concise solution, though maybe Java strings will add unneeded worktime too:
substring() is O(length copied), not O(1).