Using global variables is your mistake, and not a kata problem. Code with global variables will work incorrectly everywhere, and not only on Codewars.

ahh I solved it, the kata don't count the global variables so I put it to the function and it works correctly. waste 2 hours to discover that :(

I attempted my code on a compiler with case 'D',3 and it return 37 but when I attempt in the kata it return 30 instead. what's the problem??

ok, this was a pretty good challenge.
I took a while to get it what's going on.

All zeros and empty strings have to pass.

https://rpruim.github.io/m252/S19/from-class/models-of-computation/dfanfa-to-regular-expression.html

Allocate enough, or big enough, objects, and the heap will run out of memory. Allocate fewer or lesser things on the heap. You shouldn't need more than 10 000 primes.

1e8 for most languages

Same here... Although I don't think it's a real issue, it's rather a "bad" problem selection with a very limited number of solutions. So it's basically free points for a 3 kyu kata! ;-)

Now let's see if there is a 4x4, 5x5, etc version!

I was running test cases in local intelliJ and was wondering why the outputs of the same inputs were different.
Does anyone also meet this issue? expected<5> get <6>

approved at some point

closing then

completely agree, check my solution.