@B4B You still didn't mark it as spoiler! x/

Not an opinion. It's just a fact.

For me this is over.

It doesn't compile in another compilers. For example try to compile it into Visual Studio C++

Also, the implementation it's not yours. You're using a builtin function that only the GCC compiler has implemented. So, I must say that it's only a nice trick. But must not be considered best practice by no means.

It's faster than other implementations (including mine)? YES
Has been implemented by you? NO
Must be considered a solution to the exercise? NO!

1. SPOILER FLAG!! Damn you! x/
2. there is always an overhead about the docker/runner/.... Comparing the performances like you do right now is totally pointless and actually totally nuts. Moreover when there are random tests, and when the time you use includes the generation of the tests too.

It works, right?