http://acm.ateneo.edu/aboutACMICPC.html
The ACM (Association for Computing Machinery) International Collegiate Programming Contest (ICPC) traces its roots to a competition held at Texas A&M in 1970 hosted by the Alpha Chapter of the UPE Computer Science Honor Society. The idea quickly gained popularity within the United States and Canada as an innovative initiative to assist in the development of top students in the emerging field of computer science.
Sample Problems (
http://acm.ateneo.edu/sampleproblems.html) :
There are hundreds of problems that you can work on for team
practice. We suggest the following sites:
The OLD UVA problem set archive:
http://acm.uva.es/problemset/
The NEW ACM live archive:
http://acmicpc-live-archive.uva.es/nuevoportal/
ACM collection of past problems:
http://icpc.baylor.edu/past/PastProblems.html
CJ Hwang's collection of Asian regional problems:
http://uweb.txstate.edu/~ch01/Problems.htm