List of Problemsets

Online judges with (mostly) ACM problems

• UVa Problemset - http://acm.uva.es/p - The Valladolid University Online Judge. Over N problems, for a reasonable value of N. The problems are culled from old contests, and online contests.

• ACM-ICPC Live Archive - http://acmicpc-live-archive.uva.es/nuevoportal/ - The 2000's ACM-ICPC Live Archive Around the World. Contains actual problems from regionals and finals from 2000 on.

• Sphere Online Judge - http://spoj.sphere.pl

• Zhejiang University Online Judge - http://acm.zju.edu.cn

• Timus Online Judge - http://acm.timus.ru

• Saratov State University Online Contester - http://acm.sgu.ru

• Peking University Judge Online of ACM ICPC - http://acm.pku.edu.cn/JudgeOnline

• El Judge Online MIPT programming contest - http://acm.mipt.ru/judge

• Programming Challenges - http://www.programming-challenges.com

• Arbiter - http://acm.sharif.edu - Sharif University's Online Judge System

• National Taiwan University Online Judge -http://acm.csie.ntu.edu.tw/ntujudge/index.php

• Handzhou Dianzi University Online Judge - http://acm.hdu.edu.cn/

• Zhejiang Gongshang University Online Judge - http://acm.zjgsu.edu.cn/JudgeOnline/

• Temporary INFOR Online Judge - http://tioj.redirectme.net:8080/JudgeOnline/

• Open CS Online Judge and Computer Science Community - http://www.open-cs.net

Programming contests

• IOI - International Olympiad in Informatics - http://olympiads.win.tue.nl/ioi/, http://www.ioinformatics.org

• MIT BattleCode Competition - http://battlecode.mit.edu

• TopCoder - http://www.topcoder.com - Quasi-weekly programming competitions from algorithms to components to marathons.

• USACO Contest - http://ace.delos.com/contestgate - Monthly contests (Nov - March)

• Z-Trening - http://www.z-trening.com - Few contests every month.

• Canadian Computing Competition - A two-stage annual olympiad. See also this categorization of past Stage 1s by topic, with solutions.

• IPSC - http://ipsc.ksp.sk

• BitWISE - http://www.bitwise.iitkgp.ernet.in

• CodeCraft - http://felicity.iiit.ac.in/codecraft/

• Challenge24 International 24-hour Programming Contest - http://ch24.org

• SPb IFMO Training Sessions - http://neerc.ifmo.ru/trains/ (Note, all problems appear to be in Russian)

• UPC2001 Internet Contest - http://contest.psu.ru/Inet (link currently broken)

• Moscow SU Virtual Contests (in Russian) - http://acm.msu.ru/virtual

• Al Zimmermann's Programming Contest - http://www.recmath.org/contest/index.php

• Inscription - http://inscription.nitk.ac.in

• South African Computer Olympiad - http://olympiad.cs.uct.ac.za/old/ - Archive of finals and IOI training contests

• CodeChef - http://www.codechef.com - Ongoing monthly algorithm programming competitions and short weekend challenges with prizes. Also has practice problems ranging from easy to hard.

• Alkhwarizm - https://iws60.iiita.ac.in/alkhwarizm/

• Codecracker - http://codecracker.mkti.in

• Codeforces - http://codeforces.com

Other

• URI Online Judge - http://www.urionlinejudge.com.br/ Programming practice site for students and teams with several problems divided into 8 categories covering several programming subjects

• USACO Training - http://ace.delos.com/usacogate - "Training" site for the USACO project

• Project Euler - http://projecteuler.net - Project Euler consists of challenging mathematical or computer science problems.

• Open Source Instititute - http://www.osix.net - Increasingly difficult "programming puzzles" to solve, including steganography, cryptography and plain-old algorithms.

• Python Challenge - http://www.pythonchallenge.com/ A series of cute puzzles to solve. You don't have to use Python (but some problems reference specific Python libraries)

Social Programming Networks

• Fudge - http://fudge.fit.edu - Compute, compete and connect on the world's first social programming network.