AtCoder
AtCoder Beginner Contest (ABC)
AtCoder's entry-level rated contest series - despite the name, it's genuinely competitive at higher problem indices, rated for contestants below 1200 with unrated participation open to everyone else.
Brabble editorial · Updated 12 Aug 2026 · Official page
Particulars
- Organiser
- AtCoder
- Mode
- Fully online, frequent (roughly weekly)
- Prize / outcome
- Rating progression; no standard cash prize for regular contests
- Team size
- Individual
- Application fee
- Free
- Rounds
- 3
What it is
AtCoder Beginner Contest (ABC) is AtCoder's most frequent contest format, aimed at newer competitive programmers but attempted by a much wider skill range in practice, since later problems in each contest get genuinely hard. A round runs 100 minutes with problems worth increasing point values (recent formats have expanded well beyond the original four-problem, 100/200/300/400 structure to include more, harder problems). Only contestants rated below 1200 have their rating affected by ABC; higher-rated participants can still compete, just unofficially.
Rounds
01. Contest window
A fixed 100-minute window with several problems (recent formats: more than the original four), attempted in any order.
02. Scoring
Ranked by total score, then by penalty time - score comes from points assigned per problem, weighted by difficulty.
03. Rating update and editorial
Ratings update for eligible (sub-1200) participants shortly after the contest, and AtCoder publishes a detailed editorial explaining every problem's solution approach.
Who can enter
- Open to anyone with an AtCoder account - no academic or age restriction
- Rated only for contestants below 1200; higher-rated participants can join unofficially
- Free to enter
What you actually get
A rating that specifically signals foundational-to-intermediate competitive programming ability, plus AtCoder's editorial write-ups after every contest - widely regarded as some of the clearest problem explanations in competitive programming, which makes ABC as much a structured learning series as a contest.
Frequently asked questions
- The earlier problems are genuinely accessible to newer programmers, but later problems in the same contest get difficult enough that experienced competitive programmers compete too - just unofficially, since ABC is only rated for contestants below 1200.
- 100 minutes, with problems weighted by difficulty - the original format was four problems worth 100/200/300/400 points, though recent contests have expanded to include more, harder problems.
- AtCoder publishes a written editorial after every contest explaining the intended solution approach for each problem, widely regarded in the competitive-programming community as clearer than most platforms' - many people work through past ABCs as structured practice rather than only competing live.
- Yes, free with an AtCoder account.
Is AtCoder Beginner Contest actually for beginners?+−
How long is an AtCoder Beginner Contest?+−
Why are AtCoder's editorials worth reading even if you don't compete live?+−
Is AtCoder Beginner Contest free to enter?+−
More guides
Checked against AtCoder's own contest pages and community reporting on scoring/rating rules, 12 Aug 2026. Problem count and point values have changed between contests - confirm the current format at atcoder.jp before relying on a specific figure.