Yes. The rule of zero is a good practice.

By "completely trivial" do you mean that the constructors are unnecessary? If so, then yes: they won't be used in most solutions.

This is a nitpick but there is no reason for the Point type not to be completely trivial.

Yeah, I don't know how finding a square root is a binary operation.

The kata is reported on the list of kata to fix, but for different reasons (although slightly related).

C++: using namespace std; should be removed from initial code. It has no reason to be, and tests rely on it. Please remove it and make the necessary changes in starter and tests.

Sure. I'll raise an issue about this now (it's suprising nobody did it before).

I don't doubt the triviality. The "using namespace std;" is part of the skeleton of the solution. Removing it causes the tests to fail because string and vector aren't found.

join and split strings is a trivial task for a 2kyu kata, moreover this is how the kata is designed, one must handle the input the way they want (there is no obligation in using this to solve the kata). I cannot see the using namespace std;, ok it's a bad practice and it probably should be removed but this is completely independent from providing helper functions.

Compared to how other katas are designed, it adds an unnecessary level of obfuscation. Combined with the fact "using namespace std;" is considered bad practice, it makes the problem more messy then it should be. It would be better to make implementing the functions yourself a requirement or design the tests not to rely on them.

Why should it be?

For C++ why is the implementations of join and split_lines not provided?

this is not a performance kata, this is a pure math kata. its so sad

I ended up learning a little intrinsics.