'and': if the first operand is True, the second operand is returned; otherwise (if the first operand is False), the first operand is returned without evaluating the second operand. 'or': if the first operand is True, the first operand is returned without evaluating the second operand; otherwise (if the first operand is False), the second operand is returned.

I don't get how this one work. Can someone explain please?

wow that is clever the I will remember the + 1 : 0 at the end for recursive

do you have doc where i can get more information about it ?

It is possible, though not exactly straight-forward.

Does this kata is possible with RegEx in java in a concise and cool maner ?

I'd love to tell you, but I'm afraid I can't read my own code anymore. I should have given all my variables meaningful names. I mean, most names in this program are fine, but why did I choose letter? Such a meaningless name. I suspect it should have been birth or salvation or spirit, but I just don't remember. I'm really sorry.

Where the fuck the Y of "Yes" come from ?

the best one so far