Yes. The rule of zero is a good practice.

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.

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.

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.

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

I ended up learning a little intrinsics.

I think it would be ideal if the int() conversion operator in c++ could be marked explicit.