I discovered multiple issues with the challenge problem of December long contest 2014.
The same solution which obtained a score of 167 7 hours ago now scores only 244 (when resubmitted again). My guess is that the judging program had bugs and was changed, but there was no announcement about it and no rejudge of the already submitted solutions.
Some of the test cases on which the score is computed during the contest are invalid. They have T>100 (while the problem statement says that T is at most 100). Moreover, at least one of these files with T>100 in fact contains fewer than T test cases inside of it (so T is larger than the actual number of existing test cases inside the file).
I sent an email to firstname.lastname@example.org about it, but I’m not sure if they will do anything about it. In case other people noticed the same issues, please comment on this post and hopefully the organizers will fix the test cases and let us know what happened to the judging program.