You may be right, but I like to avoid boilerplate whenever possible. In my opinion it enhances readability to use situational syntactic sugar like this: because it can only be used in certain circumstances, its use highlights that you are in those circumstances.

Example tests are already there, you have to deduce the logic on your own though

Perfectly servicable and efficient. Wouldn't best practices encourage adding a return line? Obviously not necessary for such simple code.

You've wrote a great elegant solution but it's very unclear. I spend half a day to understand what your code actually does. It is the case where comments are absolutely necessary

That's some trolling indeed

Smart way to do recursive function in R, thanks a lot.

It's a great feature of R ;)

Love the check for zero using conversion to logical!

Yeah that's very confusing.

beautiful work

Why do people for this as best practice?

You can already see that in the example in the description.

The description needs to address how to handle 0, that knowledge is obviously required to pass the tests.

Oh well.

You're right, but the kata description explicitly says "It is guaranteed that a and b are both present in arr", so for this specific task this does the trick.