But as requested, I have solved again without imports :)

? My "criticism" was just showing how the original reference solution was wrong, which you fixed. I also commented a warning (to your friend, as it turned out) to not copy solutions, but that was no criticism of the kata.

I don't remember any original comment about imports in the description. I suspect you added that after you saw other solutions. Merely requesting people to not use imports is also not a good idea, by the way. Even if people comply during beta phase, once approved, many people will simply ignore it, to get easy points.

If you want the kata to be properly ranked at a level where users must implement their own data structures, then you need to actually ban the imports. However doing so is actually a lot more difficult than you might think.