When I was preparing for the entering exam of The University of Tokyo, I have solved some ACM problems for about 2 month. And here's some of it.
But I have't wrote any annotation for these codes, since I thouht that I don't have to show these codes to someone else at that time.
You can find these problems in http://poj.org/ for example, the URL of Problem No.1077 is : http://poj.org/problem?id=1077