[How to get an account / participate in contests?](http://atcoder.jp/posts/2) [AtCoder's Contest Format](http://atcoder.jp/posts/1) - [AtCoder's Testcases](https://www.dropbox.com/sh/nx3tnilzqz7df8a/AAAYlTq2tiEHl5hsESw6-yfLa?dl=0) - [AtCoder's Rating System](https://www.dropbox.com/sh/zpgcogxmmu84rr8/AADcw6o7M9tJFDgtpqEQQ46Ua?dl=0) AtCoder Race Ranking: [2024 Algo](https://img.atcoder.jp/file/gp30/race2024.html), [2024 Heuristic](https://img.atcoder.jp/file/gp30/race2024H.html) Beware of suspicious websites claiming to be AtCoder. [Click here](https://atcoder.jp/posts/1269) for more information.

As announced in the [Announcement Regarding ARC's Division System](https://atcoder.jp/posts/1365), ARC has been split into two types: Div. 1 and Div. 2. Among these, only Div. 2 will be subject to the [AtCoder Rules against Generative AI](https://info.atcoder.jp/entry/llm-rules-en), while Div. 1 will be exempt. Accordingly, we have made changes to the rule text. The main changes are as follows: - Replaced "ARC" with "ARC Div. 2" - Added specific examples For detailed differences, please check [here](https://github.com/atcoder/rules/commit/2f45ffa39d33fbe15fe657adb0c026b83636ea06).

We have recently detected attempts by third parties to gain unauthorized access to atcoder.jp accounts using email addresses and passwords that are likely leaked from other services. If you are using the same combination of email address and password for AtCoder as you do for other services, or if you have set a password that is easily guessable even if you use different passwords for each service, your account may be vulnerable to unauthorized access. If you are reusing passwords across services or using easily guessable passwords, we strongly encourage you to update your password to a more secure one. You can change your password by logging in and visiting the following page: https://atcoder.jp/settings/password?lang=en Additionally, to help users detect unauthorized access, we have implemented login notification emails that will be sent to your registered email address whenever you log in. Please ensure that your registered email address is correct by verifying it through the following link: https://atcoder.jp/settings/mail?lang=en

Starting from [ARC189](https://atcoder.jp/contests/arc189), AtCoder Regular Contest will be split into two divisions based on difficulty: Div. 1 and Div. 2. - **AtCoder Regular Contest (Div. 1)** - Rated range: 1600 ~ 2799 - Approximate point values: 800-800-900-900-1000 - **AtCoder Regular Contest (Div. 2)** - Rated range: 1200 ~ 2399 - Approximate point values: 400-500-600-700-800 ### Special Notes - Only Div. 1 will allow the use of generative AI (it may be prohibited again depending on future circumstances) - We plan to hold Div. 1 at least 8 times per year and Div. 2 at least 12 times per year - The number of problems may vary (particularly, Div. 2 may have 6 problems) ### Objectives - Make Div. 1 focused on competition for yellow to orange users - Hold Div. 2 with easier problems and maintain contests that can be enjoyed by users across a wide range of ratings - Raise the lower difficulty threshold of Div. 1 to exclude it from generative AI rules ### Related Articles - [Restructuring of contests](https://atcoder.jp/posts/1281) - [Regarding Rule Changes in ABC and ARC Due to Technological Advancement of Generative AI](https://atcoder.jp/posts/1350)

Generative AI has evolved further, and its performance in competitive programming has improved. While the overall impact of generative AI on ratings is not significant at present, there is considerable dissatisfaction among users, and the enjoyment of competition has been greatly diminished. To overcome this situation and make competitive programming more enjoyable, we have decided to impose even stricter prohibitions on the use of generative AI than before. There are significant changes to the rules, so please make sure to review them. These rules apply to both ABC and ARC. They do not apply to AGC, where we plan to only include problems that generative AI cannot solve correctly. ## Rules For detailed rules, please check the following page: - [AtCoder Rules against Generative AI - Version 20241115](https://info.atcoder.jp/entry/llm-rules-en-20241115) To summarize the rules, the main points are as follows: - When using generative AI for code generation, only completion aimed at increasing coding speed is permitted. It must not be used to solve problems or sub-problems, or to obtain ideas. - Translation into various languages or conversion to other programming languages is only permitted in the formats specified in the rules. ## Rule Creation Guidelines and Future Rule Changes The guidelines for creating rules have not changed significantly since the previous rule establishment. Based on the evolution of generative AI, we updated the rules believing that adding restrictions on using generative AI for coding and ideation would better preserve the "joy of thinking through solutions" in competitive programming. We believe that competitive programming has always been a competition based on participants' conscience. Please cooperate in preserving the culture of competitive programming. If we detect many users clearly violating the rules, we are considering strict measures, including blocking access from those groups to specific contests and taking legal action. Depending on future developments in generative AI and trends among users, we may impose additional restrictions, such as prohibiting the use of specific services. We will continue to post rules in easily accessible locations, so please stay informed.

We will restructure the contests. - Admins (From September 2024) - The admin of AWTF will be <a href="/user/maroonrk" class="username"><span style="color:#869120;">maroonrk</span></a>. (no change) - The admin of AGC will be <a href="/user/maroonrk" class="username"><span style="color:#869120;">maroonrk</span></a>. (no change) - The admin of ARC will be changed from <a href="/user/maroonrk" class="username"><span style="color:#869120;">maroonrk</span></a> to <img src="//img.atcoder.jp/assets/icon/crown_silver.png"> <a href="/user/snuke" class="username"><span style="color:#1000AC;">snuke</span></a>. - The admin of ABC will be <img src="//img.atcoder.jp/assets/icon/crown_silver.png"> <a href="/user/snuke" class="username"><span style="color:#1000AC;">snuke</span></a>. (no change) - Frequency of contests - We will hold AWTF once per year. - From August 2024 to December 2024, we will hold AGC once per month. The frequency of AGC in 2025 hasn't been decided yet. - We will hold ARC once or twice per month. At least 20 per year. - We will hold ABC almost every week. - Rated ranges (from AGC067/ARC184) - We will raise the lower bound of the rated range of AGC to 2000. (no upper bound) - We will raise the lower bound of the rated range of ARC to 1200. (The upper bound will remain 2799) - The rated range of ABC will be 0-1999. (no change) - The difficulties and the point values of ARC (From September 2024 / ARC 184) - The problems will be mainly adjusted for yellows and oranges. - If we predict that a problem will be solved by about half of the participants around rating 2000, we will usually assign 600 points to the problem (sometimes we may slightly adjust it for various reasons). Similarly, 2400 - 800, 2800 - 1000. - We will mainly use problems with 600 points or lower for A/B, problems between 600-1000 points for C/D/E, and problems with 1000 points or higher for F. - The difficulty of problems A/B/C/D will be similar to recent ARCs. E/F (especially E) will be easier.