Codeforces
Programming · Applications open · Organiser: Codeforces
An online platform running regular algorithm contests from Div. 1 to Div. 4. Ratings change after each contest; thousands of archived problems and editorials support steady practice.
Who can take part?
Free and open to everyone; create an account and register for contests.
How to prepare
Start with Div. 3 and Div. 4 rounds and read the editorial for every problem you missed. Set a weekly virtual-contest hour as a club.
Official page · All competitions
Last checked: 2026-11-03