I suggest visiting this
Lots of problems, even very difficult to solve.
They don't require knowing a specifical programming language. They measure (well, they're supposed to do) problem-solving skill. Tell me what do you think about them. See you
Re: Algorithm questions...
Replies are listed 'Best First'.
The way it was explained in the Imprint (UW newspaper) is that points get deducted every time an incorrect solution is submitted. So, UW's team submitted wrong answers (several times, if I remember) and lost enough points to fall be St. Petersburg.
They apparently changed Contest Rules while I was looking somewhere else :). Well, I don't like new Rules: I think ACM Contest should answer the question: "Who can solve as many problems as possible, given 5 hours, a computer and a Judging System?". This question in some cases is supposed to mimic another question "Who is the best programming team?". In my opinion, and in that sense, Waterloo University is 1999's Contest Winner ;)