So it still fails three months later. Is there a solution to the problem of the servers giving 500s?

The language is C.

I am printing nothing to the console.

The solution is not recursive, I do use a loop however. The maximum function depth in my code is 2.

I allocate the output buffer with malloc and I have tried different values. All sensible values work with the supplied tests.

Most of the times it works it keeps failing at the large input batch. It passed the first two, but the third not. I tried upping the amount in malloc and it still doesn't help.
Most of the times, though, I would say 90%, I get the upper error and this one https://i.imgur.com/xuqnUnQ.png

To me, a person who doesn't know much about the infrastructure of codewars, it seems that the “Attempt” servers aren't really stable with big input or output. I may be wrong, but what should I do to make it work?

@Varveyn , Can you check if there's something wrong with the compiler / tester? I have made a solution which passes the supplied tests. But when I “Attempt” it the only thing I get is this:
https://i.imgur.com/iikigTl.png
It's an Internal Server Error (500).

It's interesting how many solutions this problem yielded. :) Awesome ones too...