Professional code golfers (Is that the right term?) build up a large suite of helper libraries from past events/from daily puzzle solving that they invoke for common problem types like graph search or constraint solving, or even for converting the text input to the right data structures.
I assume the most difficult aspect of the problems is to translate the statements into actual code constraints/filter functions. So the spirit of the competition is not broken by having pre-written code (Although I am not sure many would think pre-written code is acceptable).