We will hold <a href="https://atcoder.jp/contests/abc430">AtCoder Beginner Contest 430</a>. - Contest URL: https://atcoder.jp/contests/abc430 - Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20251101T2100&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/user/user-orange-2.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-3.png" class="user-rating-stage-m"><a href="/users/sheyasutaka" class="username"><span class="user-orange">sheyasutaka</span></a>, <img src="//img.atcoder.jp/assets/user/user-orange-3.png" class="user-rating-stage-m"><a href="/users/Nyaan" class="username"><span class="user-orange">Nyaan</span></a> - Rated range: ~ 1999 - The point values: 100-250-300-400-450-500-625 We have updated the rating system. As these changes will apply starting with this contest, please see [this post](https://atcoder.jp/posts/1592) for details. We are looking forward to your participation!

In AtCoder’s rating system, when calculating ratings after a contest, the internal rating of first-time participants has been set to a fixed provisional value (currently 800 for all new users). This fixed value was last updated six years ago. Since then, we believe that the skill level of first-time participants has increased—both in terms of individual ability and relative to other contestants. This trend likely stems from several factors, such as the availability of better learning resources and an increase in participants with experience in overseas contests. In any case, we expect this upward trend to continue. To reflect these changes, we have decided to revise the initial internal rating for first-time participants from 800 to 1200. We simulated the expected rating distribution two years after this change using historical contest data, and obtained the following results: - Rating changes will not occur abruptly, and users with fewer contest participations will see only minor changes. - Users in the rating range affected by ABC contests will experience the most noticeable effects. Those who continue participating for two years may see an increase of around +200. - Among users whose ratings are no longer affected by ABC contests, higher-rated participants will experience smaller changes. For example, users with ratings above 2800 will see at most about a +30 increase even after two years. This change is scheduled to take effect starting from ABC 430, which will be held this weekend. We will continue to monitor the situation closely and strive to provide an even better rating system in the future. Thank you for your continued support.

We will hold <a href="https://atcoder.jp/contests/agc074">AtCoder Grand Contest 074</a>. This contest counts for GP30 scores. - Contest URL: https://atcoder.jp/contests/agc074 - Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20251026T2100&p1=248 - Duration: 180 minutes - Number of Tasks: 5 - Writer: <img src="//img.atcoder.jp/assets/user/user-orange-3.png" class="user-rating-stage-m"><a href="/users/hint908" class="username"><span class="user-orange">hint908</span></a>, <img src="//img.atcoder.jp/assets/user/user-orange-1.png" class="user-rating-stage-m"><a href="/users/vwxyz" class="username"><span class="user-orange">vwxyz</span></a> - Tester: <img src="//img.atcoder.jp/assets/icon/crown_bronze.png"> <a href="/users/IH19980412" class="username"><span class="user-red">IH19980412</span></a> - Rated range: 2000 ~ The point values will be 700-800-900-1100-1200. We are looking forward to your participation!

We will hold <a href="https://atcoder.jp/contests/abc429">Polaris.AI Programming Contest 2025（AtCoder Beginner Contest 429）</a>. - Contest URL: https://atcoder.jp/contests/abc429 - Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20251025T2100&p1=248 - Duration: 100 minutes - Writer: <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/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-2.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/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-2.png" class="user-rating-stage-m"><a href="/users/MMNMM" class="username"><span class="user-orange">MMNMM</span></a> - Rated range: ~ 1999 - The point values: 100-200-300-425-450-525-625 We are looking forward to your participation!

We will hold <a href="https://atcoder.jp/contests/ahc055">RECRUIT Nihonbashi Half Marathon 2025 Autumn （AtCoder Heuristic Contest 055）</a>. - Contest URL: https://atcoder.jp/contests/ahc055 - Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20251019T1900&p1=248 - Duration: 4 hours - Staff: <a href="https://atcoder.jp/users/cozy_sauna?contestType=heuristic" class="username user-yellow"><span class="user-yellow">cozy_sauna</span></a>, <a href="https://atcoder.jp/users/crinoid_t" class="username user-gray"><span class="user-gray">crinoid_t</span></a>, <a href="https://atcoder.jp/users/dpforest" class="username user-blue"><span class="user-blue">dpforest</span></a>, <a href="https://atcoder.jp/users/eha" class="username user-yellow"><span class="user-yellow">eha</span></a>, <a href="https://atcoder.jp/users/FLOPPY_30" class="username user-blue"><span class="user-blue">FLOPPY_30</span></a>, <a href="https://atcoder.jp/users/frnfnts" class="username user-cyan"><span class="user-cyan">frnfnts</span></a>, <a href="https://atcoder.jp/users/hamray" class="username user-blue"><span class="user-blue">hamray</span></a>, <a href="https://atcoder.jp/users/hashiryo" class="username user-yellow"><span class="user-yellow">hashiryo</span></a>, <a href="https://atcoder.jp/users/hedwig" class="username user-blue"><span class="user-blue">hedwig</span></a>, <a href="https://atcoder.jp/users/japlj" class="username user-red"><span class="user-red">japlj</span></a>, <a href="https://atcoder.jp/users/kanra824" class="username user-blue"><span class="user-blue">kanra824</span></a>, <a href="https://atcoder.jp/users/kys" class="username user-blue"><span class="user-blue">kys</span></a>, <a href="https://atcoder.jp/users/miz56" class="username user-blue"><span class="user-blue">miz56</span></a>, <a href="https://atcoder.jp/users/n_knuu" class="username user-blue"><span class="user-blue">n_knuu</span></a>, <a href="https://atcoder.jp/users/roiti" class="username user-blue"><span class="user-blue">roiti</span></a>, <a href="https://atcoder.jp/users/ruthen71" class="username user-yellow"><span class="user-yellow">ruthen71</span></a>, <a href="https://atcoder.jp/users/samasama" class="username user-green"><span class="user-green">samasama</span></a>, <a href="https://atcoder.jp/users/shichinomiya" class="username user-cyan"><span class="user-cyan">shichinomiya</span></a>, <a href="https://atcoder.jp/users/shiratty8" class="username user-yellow"><span class="user-yellow">shiratty8</span></a>, <a href="https://atcoder.jp/users/smiken" class="username user-orange"><span class="user-orange">smiken</span></a>, <a href="https://atcoder.jp/users/sugim48" class="username"><span style="color:#C06000;">sugim48</span></a>, <a href="https://atcoder.jp/users/suzume?contestType=heuristic" class="username user-orange"><span class="user-orange">suzume</span></a>, <a href="https://atcoder.jp/users/tomerun?contestType=heuristic" class="username user-red"><span class="user-red">tomerun</span></a>, <a href="https://atcoder.jp/users/yupiteru?contestType=heuristic" class="username user-yellow"><span class="user-yellow">yupiteru</span></a>, <a href="https://atcoder.jp/users/yusk" class="username user-cyan"><span class="user-cyan">yusk</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>. This contest will be held using the new judge system. For more details, please see <a href="https://atcoder.jp/posts/1580">this page</a>. We are looking forward to your participation!

We will hold <a href="https://atcoder.jp/contests/abc428">AtCoder Beginner Contest 428</a>. - Contest URL: https://atcoder.jp/contests/abc428 - Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20251018T2100&p1=248 - Duration: 100 minutes - Writer: <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>, <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> - Tester: <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-2.png" class="user-rating-stage-m"><a href="/users/physics0523" class="username"><span class="user-orange">physics0523</span></a> - Rated range: ~ 1999 - The point values: 150-200-300-400-475-525-625 We are looking forward to your participation!

We will hold <a href="https://atcoder.jp/contests/arc208">AtCoder Regular Contest 208 (Div. 2)</a>. - Contest URL: https://atcoder.jp/contests/arc208 - Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20251012T2100&p1=248 - Duration: 120 minutes - Number of Tasks: 5 - 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> - 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: 1200 ~ 2399 The point values will be 500-600-700-700-1100. We are looking forward to your participation!

We will hold <a href="https://atcoder.jp/contests/abc427">Panasonic Programming Contest 2025（AtCoder Beginner Contest 427）</a>. - Contest URL: https://atcoder.jp/contests/abc427 - Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20251011T2100&p1=248 - Duration: 100 minutes - Writer: <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/icon/crown_bronze.png"> <a href="/users/cn449" class="username"><span class="user-red">cn449</span></a>, <a href="/users/evima" class="username"><span class="user-unrated">evima</span></a> - Tester: <img src="//img.atcoder.jp/assets/user/user-orange-3.png" class="user-rating-stage-m"><a href="/users/toam" class="username"><span class="user-orange">toam</span></a>, <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> - Rated range: ~ 1999 - The point values: 100-200-350-425-500-525-625 We are looking forward to your participation!

We will hold <a href="https://atcoder.jp/contests/arc207">AtCoder Regular Contest 207 (Div.1)</a>. - Contest URL: https://atcoder.jp/contests/arc207 - Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20251005T2100&p1=248 - Duration: 150 minutes - Number of Tasks: 5 - Writer: <img src="//img.atcoder.jp/assets/user/user-orange-4.png" class="user-rating-stage-m"><a href="/users/camypaper" class="username"><span class="user-orange">camypaper</span></a> - Tester: <a href="/users/maroonrk" class="username"><span style="color:#869120;">maroonrk</span></a>, <img src="//img.atcoder.jp/assets/icon/crown_silver.png"> <a href="/users/snuke" class="username"><span style="color:#1000AC;">snuke</span></a> - Rated range: 1600 ~ 2999 The point values will be 800-800-800-800-800. Please note that the rules against generative AI were updated on October 3, 2025. Please make sure to read [this post](https://atcoder.jp/posts/1568) and [the rules](https://info.atcoder.jp/entry/llm-rules-en). We are looking forward to your participation!

We will hold <a href="https://atcoder.jp/contests/abc426">AtCoder Beginner Contest 426</a>. - Contest URL: https://atcoder.jp/contests/abc426 - Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20251004T2100&p1=248 - Duration: 100 minutes - Writer: <img src="//img.atcoder.jp/assets/user/user-orange-2.png" class="user-rating-stage-m"><a href="/users/physics0523" class="username"><span class="user-orange">physics0523</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>, <a href="/users/evima" class="username"><span class="user-unrated">evima</span></a> - Tester: <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>, <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> - Rated range: ~ 1999 - The point values: 100-200-300-400-450-525-575 Starting with this contest, the rules against generative AI have undergone significant changes. Please make sure to review [this post](https://atcoder.jp/posts/1568) and [the rules](https://info.atcoder.jp/entry/llm-rules-en). We are looking forward to your participation!