Why? For a 4 kyu challenge one would think you should be able to add a class on your own.

Sure, but it's just more convenient. People are here to solve some algorithmic/math tasks, not to learn how to create a class in python.

@pipo: Yes, that is correct. All foreigners are banned at the start.

Just to expand on this, I believe (please correct me if I'm wrong) that all citizens of other nations actually begin as "banned" unless and until a bulletin states that they are allowed. Of course citizens of nations may be banned/allowed during the execution of the tests, but they all begin as banned as far as I remember?

cheers, Phil

If there was a bulletin that stated "Deny citizens of NATION" (where NATION is the nation of the entrant in question), and there weren't any subsequent bulletins that stated to allow citizens of NATION, and there is no reason for detainment of the entrant.

Could someone explain me, please, when do i need to return "Entry denied: citizen of banned nation." I just couldn't get the logic for this case.

As somebody who is a bit newer here, I don't think that it should be 2kyu if the few I have seen are anything to base it off of, but I also agree that it shouldn't be 5kyu. I would rate it a 4, myself.

What was the reason of changing the level of this kata from 2kyu to 5kyu?
I think that this kata is much more harder than average 5kyu kata on this site.

"^" is an xor logical operator in java. You are looking for "Math.pow(double a, double b)".

yaa, testcase is dreadfull! :D

This code doesn't consider cubes of size 1 (n = 1), nor cubes without size (n = 0). Test cases are too loose :)