When we (me, Sayyed Vahab Mirrokni, Ehsan Chiniforooshan) were preparing for ACM programming contest, we developed a bunch of functions which we believe are useful for this contest.
You can download these utility functions through this page. Note that there is no guarantee on correctness of these codes. We tried to do our best preparing them, but there may be some errors. Also the major infect is that, codes are not documented well, so I hope the name of variables and functions are self descriptive enough to understand them. All codes are in Pascal which was our preferable programming language those days! But the key points are algorithms that can be transfered to any high level language easily.