Ruby translation
https://www.codewars.com/kumite/626da82056f97e792802ea83?sel=626da82056f97e792802ea83

You can't submit in a Draft.

Can't submit my solution even though it passes all tests (test and attempt in JavaScript).
I see congratulation and offering Submit when ready, but there is no Submit button.

And doesn't work for Integer.MIN_INTEGER? No thanks

Where can I see how many tests pass?

I found out that the Ruby version shows how many tests passed and the Elixir one does not.

C++ is generally much faster than Ruby, but it provides less syntactic sugar, less built-in facilities... In many katas an algorithm working in a language won't work with another. Think about an assembly language like NASM, where the simplest algorithm rated 7 kyu may be harder than 4 kyu in most others. What should be done? It's impossible to reach fairness between languages, they are so different.

No indication is given on how to distinguish tail from loop.

String sNum = "" + Math.abs(num);
let you eliminate second string.