C++ test cases produce warnings because counters in loops have wrong type. Those should be size_t instead of int,

Thanks. The correct solution passes now.

Ok, I know Haskell, how do I fix it? Do I need some rep/permissions to do so?

Yes, that is in haskell. I have the solution, but I am new to codewars, so I don't know how to edit the kata(or to get proper permissions to do so).

The authors solution is incorrect. It reverses the input if it does not contain dots...
So authors solution treats strings "123" as "321", examples from other comments:
"34" becomes "43", then "44" instead of correct "35"
"76" becomes "67", then "68" instead of correct "77"

I have both correct and bugged solutions for this problem. So if there is someone, who can correct the kata you can use mine to fix it.

This kata description is missing boundaries for the values, the size of the array and whether the given numbers are all positive.