It's probably been a long time since you did this kata. I'm trying to understand your recursion but i keep getting lost in the way. Would it be too much to ask for your help?
I had to at least try asking.

It's all about reading and learning. All those wheels are out there, no need to reinvent them.

Nice one liner but it takes twice the amount of time to process than the top voted ones.

Certainly the most efficient solution for the real world, but...