After you have unpacked the archive, you will see two subdirectories, prac/ and real/ for the practice contest and the real contest. Each of these directories contain a subdirectory for each problem. The subdirectory contains judging data (*.dat are the input files, and *.diff are the output files) and sample solutions from the judges.
Note: some judges' solutions may actually not be judged correct in a real contest situation because they run too long, use up too much memory, etc. They were used by the judges to decide a suitable time limit for the problem set.