UVa

The Valladolid University Online Judge (UVa) Problemset
http://acm.uva.es/problemset

History
This site has been around for quite awhile, with over 4 million submissions as of November 26th, 2005.

Problems
Please use the Problem Template when adding new problems. The easiest way of doing it: start editing an empty page, type " " and save the page. The template will be inserted. Now, start editing the page again and fill in the template.

felix-halim.net
An archive of helper utilities, such as a statistics comparer, a sorting of the easiest problems and separated ranklists for the countries.

Methods to Solve
Compilation of various methods to solve the problems. Has methods for about 35% of the problems.