compsci

If you’re not already familiar with it, the TopCoder programming competition is an ongoing online competition complete with prizes.  There is a high school division.  All of the former problems are up online and can be done at any time.  Students can get their feet wet practicing on these problems, and then compete in the weekly competitions if they want. 

The way TopCoder works is you enter the “arena” and are given a problem.  You have a set amount of time to solve the problem.  Problems are always in the form of “accept input in the form of … and return the result in the form of…”  Grades are given on how fast your problem runs on different data.  Fastest solution wins.