Contest
Permanent Contests
First-time users: practice contest / Library testing: AtCoder Library Practice Contest
Upcoming Contests
Recent Contests
Ranking: Algorithm
<a href="https://www.youtube.com/live/GSXLhawvkYE"><img src="https://img.atcoder.jp/awtf2025heuristic/awtf2025algo_en720.png"></a>
<a href="https://www.youtube.com/live/TG3ChQH61vE"><img src="https://img.atcoder.jp/awtf2025heuristic/awtf2025heu720.png"></a>
Important announcements
- [2025-07-19] Generative AI Rule Changes Regarding ARC Div. 1
- [2025-06-16] Introduction of Generative AI Rules in AHC
- [2025-04-17] Regarding Judge Queue Delays and Future Measures
- [2025-03-20] Changes to the Rated Cap of ARC Div.1
- [2025-01-17] AHC's New Rating System
- [2025-01-15] Tentative 2025 AHC Schedule
- [2025-01-15] Announcement of AtCoder World Tour Finals 2026
- [2024-12-16] Information
- [2024-12-06] Regarding Rule Changes in ABC and ARC Due to Technological Advancement of Generative AI
- [2024-12-04] Password Management for Your AtCoder Account
- [2024-12-03] Announcement Regarding ARC's Division System
- [2024-08-08] Restructuring of contests
Recent contest announcements
- [2025-08-29] New AtCoder Beginner Contest 421 Announcement
- [2025-08-22] AtCoder Beginner Contest 420 Announcement
- [2025-08-22] AtCoder Heuristic Contest 052 Announcement
- [2025-08-26] New Maintenance notification (Finished)
- [2025-08-15] AtCoder Regular Contest 204 (Div. 1) Announcement
We will hold <a href="https://atcoder.jp/contests/abc421">AtCoder Beginner Contest 421</a>.
- Contest URL: https://atcoder.jp/contests/abc421
- Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20250830T2100&p1=248
- Duration: 100 minutes
- Writer: <img src="//img.atcoder.jp/assets/user/user-orange-1.png" class="user-rating-stage-m"><a href="/users/kyopro_friends" class="username"><span class="user-orange">kyopro_friends</span></a>, <img src="//img.atcoder.jp/assets/icon/crown_bronze.png"> <a href="/users/yuto1115" class="username"><span class="user-red">yuto1115</span></a>, <img src="//img.atcoder.jp/assets/user/user-orange-3.png" class="user-rating-stage-m"><a href="/users/sheyasutaka" class="username"><span class="user-orange">sheyasutaka</span></a>
- Tester: <img src="//img.atcoder.jp/assets/user/user-orange-4.png" class="user-rating-stage-m"><a href="/users/mechanicalpenciI" class="username"><span class="user-orange">mechanicalpenciI</span></a>, <img src="//img.atcoder.jp/assets/icon/crown_bronze.png"> <a href="/users/cn449" class="username"><span class="user-red">cn449</span></a>
- Rated range: ~ 1999
- The point values: 100-200-350-425-475-525-600
We are looking forward to your participation!
We will hold <a href="https://atcoder.jp/contests/abc420">AtCoder Beginner Contest 420</a>.
- Contest URL: https://atcoder.jp/contests/abc420
- Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20250824T2100&p1=248
- Duration: 100 minutes
- Writer: <img src="//img.atcoder.jp/assets/user/user-orange-1.png" class="user-rating-stage-m"><a href="/users/sounansya" class="username"><span class="user-orange">sounansya</span></a>, <img src="//img.atcoder.jp/assets/user/user-orange-1.png" class="user-rating-stage-m"><a href="/users/physics0523" class="username"><span class="user-orange">physics0523</span></a>
- Tester: <img src="//img.atcoder.jp/assets/user/user-orange-2.png" class="user-rating-stage-m"><a href="/users/MMNMM" class="username"><span class="user-orange">MMNMM</span></a>, <img src="//img.atcoder.jp/assets/user/user-orange-3.png" class="user-rating-stage-m"><a href="/users/sheyasutaka" class="username"><span class="user-orange">sheyasutaka</span></a>
- Rated range: ~ 1999
- The point values: 100-200-300-400-450-550-575
We are looking forward to your participation!
We will hold <a href="https://atcoder.jp/contests/ahc052">AtCoder Heuristic Contest 052</a>.
- Contest URL: https://atcoder.jp/contests/ahc052
- Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20250823T1500&p1=248
- Duration: 4 hours
- Writer: <a href="/users/wata_admin" class="username"><span class="user-unrated">wata_admin</span></a>
- Rated range: All (Heuristic Rating)
This contest is one of the qualifying contests for <a href="https://atcoder.jp/posts/1394">AWTF 2026</a>.
We are looking forward to your participation!
Dear users,
We are going to suspend our service on the following schedule for maintenance.
【Schedule】
- Start time: 2025-08-25 16:00:00 (UTC)
- ~~End time: 2025-08-25 19:00:00 (UTC)~~ 17:14(UTC)
【Affected Resource】
- [https://atcoder.jp](https://atcoder.jp)
We apologize for the inconvenience to our users. Thank you for your understanding.
We will hold <a href="https://atcoder.jp/contests/arc204">AtCoder Regular Contest 204 (Div. 1)</a>.
- Contest URL: https://atcoder.jp/contests/arc204
- Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20250817T2100&p1=248
- Duration: 150 minutes
- Number of Tasks: 4
- Writer: <img src="//img.atcoder.jp/assets/icon/crown_bronze.png"> <a href="/users/potato167" class="username"><span class="user-red">potato167</span></a>
- Tester: <img src="//img.atcoder.jp/assets/user/user-orange-4.png" class="user-rating-stage-m"><a href="/users/Nyaan" class="username"><span class="user-orange">Nyaan</span></a>, <img src="//img.atcoder.jp/assets/icon/crown_bronze.png"> <a href="/users/maspy" class="username"><span class="user-red">maspy</span></a>
- Rated range: 1600 ~ 2999
The point values will be 700-800-900-1000.
We are looking forward to your participation!