More seriously you can easily imagine Rosetta Code as just a way of teaching something, without an expectation that you'll compile or run it. In other words it is documentation, the fact that some of it is also code isn't a problem.
Instead of solving simple, common problems in many programming languages so that nobody has to ever do so again, this seems to make programming harder by excluding such solutions from being used.
So now you have to find work arounds in order to NOT use the simple solutions in Rosetta.
This is so evil.
Should be called the tower of babel of code, rather than the rosetta stone.
Ask the Numerical Recipes guys!
But for real, you can use this code, I don't think anyone said that you couldn't.
No, you absolutely cannot. This is how copyright works by default.
You'd need to relicense your code, with the permission of anyone else who owns copyright to it, to this documentation license.
There is not anyone who can use code under this license, in practice.