Yeah, php has a vulernability on codewars which makes any test without rng cases exploitable.
But there doesn't seem to be any activity on the platform from it's creators.

That is ok, pfela.
"Best" is a relative word and your solution seems to have better performance.
I just thoght in a simple solution, but you are right. I am using array_slice to retrieve something I could put in a cache and improve performance.