This guy's library can be contained within your submission source code, so it can be used. BOOST in any case won't be installed or would be kept out of execution sandbox, on the judge server, so BOOST won't be usable. STL will be present along the gcc version they use by default. S = Standard in STL :)

You can anything you like in paper form to the competition, so you could print this guys thing and type it in at the competition. You could certainly do the same for boost (but you'd be limited to the very small subset that is easy to type in).

At least, this is how it was seven years ago.