According to really best practices, floating point numbers should only participate in strict inequalities.

I am a beginner and I am wondering if it is worth it to add a whole library to the project only to use the simple accumulate function which can be done with one line of ranged for loop.

wow

I learn new standard library methods by seeing other people's solutions WAY faster than reading by the references.

me neither... I'm just looking at it and I'm like ..??
Did you figure out why that's correct? I don't even know how I should google it 🤔🤔

I don't understand the w/h/h?

floating points

(w/h*h == w/h/h) ? find_math_class() : call_out_lies();

Experience not cheating.

My code can work for all collections, yours only for std::vector.

cheating...

your solution is not recursive