We will hold AtCoder Grand Contest 073.↵
This contest counts for GP30 scores.↵
↵
- Contest URL: https://atcoder.jp/contests/agc073↵
- Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20250928T2100&p1=248↵
- Duration: 180 minutes ↵
- Number of Tasks: 4↵
- Writer: [user:maroonrk,2025-09-27]↵
- Tester: [user:maspy,2025-09-27], [user:HIR180,2025-09-27]↵
- Rated range: 2000 -↵
↵
The point values will be 700-1000-1400-1700. ↵
↵
We are looking forward to your participation!↵
↵
**UPD and announcement about the AI usage in this contest**↵
↵
First of all, I'm terribly sorry for what happened today; Problem C was solved by an AI.↵
It is legal to use AI in AGC contests.↵
However, this rule was adopted under the assumption that we would not provide problems that are solvable solely by AI.↵
What makes the situation worse is that, as far as I know, only paid plans are able to solve this problem.↵
This is especially serious, and I fully accept your frustration.↵
↵
Of course, I tested this problem (and other problems) with GPT5-Pro until I reached the query limit, and it didn't succeed.↵
I should also note that the initial version of C was asking for a slightly different thing, and I tested the current statement only twice, but I don't think that's the root cause of this incident.↵
↵
I should have paid more attention to the development of AI.↵
I knew that some hard CF/IOI/ICPC/PE/etc. problems were solved by AI.↵
Many people asked me about whether (or when) to ban AI in AGC.↵
I had several chances to reconsider the rules.↵
However, I was overconfident and thought, "Hmm, there do exist good problems that aren't solvable by AI, so I can just choose them."↵
As you know, I didn't have the ability to identify such problems.↵
↵
As I said, the current rules of AGC don't restrict the use of AI, so making the contest unrated would feel like applying an ex post facto law.↵
Therefore, my current plan is as follows:↵
↵
- Keep this contest rated (and count GP30 scores).↵
- Ban AI for future AGC contests.↵
- Hold more AGCs to mitigate the effects of this incident.↵
↵
To realize the third point, I have to reconsider the style of AGC.↵
I'm not exactly sure about what changes to make, but one possible idea is to make a contest that is somewhere between ARC Div.1 and the current AGC.↵
↵
Again, this is entirely my mistake and I sincerely apologize to all participants.↵
I would also like to express my deepest gratitude to everyone who participated in this contest under such circumstances.↵
↵
AGC admin,↵
maroonrk↵
↵
[original post on AtCoder](https://atcoder.jp/posts/1564)
This contest counts for GP30 scores.↵
↵
- Contest URL: https://atcoder.jp/contests/agc073↵
- Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20250928T2100&p1=248↵
- Duration: 180 minutes ↵
- Number of Tasks: 4↵
- Writer: [user:maroonrk,2025-09-27]↵
- Tester: [user:maspy,2025-09-27], [user:HIR180,2025-09-27]↵
- Rated range: 2000 -↵
↵
The point values will be 700-1000-1400-1700. ↵
↵
We are looking forward to your participation!↵
↵
**UPD and announcement about the AI usage in this contest**↵
↵
First of all, I'm terribly sorry for what happened today; Problem C was solved by an AI.↵
It is legal to use AI in AGC contests.↵
However, this rule was adopted under the assumption that we would not provide problems that are solvable solely by AI.↵
What makes the situation worse is that, as far as I know, only paid plans are able to solve this problem.↵
This is especially serious, and I fully accept your frustration.↵
↵
Of course, I tested this problem (and other problems) with GPT5-Pro until I reached the query limit, and it didn't succeed.↵
I should also note that the initial version of C was asking for a slightly different thing, and I tested the current statement only twice, but I don't think that's the root cause of this incident.↵
↵
I should have paid more attention to the development of AI.↵
I knew that some hard CF/IOI/ICPC/PE/etc. problems were solved by AI.↵
Many people asked me about whether (or when) to ban AI in AGC.↵
I had several chances to reconsider the rules.↵
However, I was overconfident and thought, "Hmm, there do exist good problems that aren't solvable by AI, so I can just choose them."↵
As you know, I didn't have the ability to identify such problems.↵
↵
As I said, the current rules of AGC don't restrict the use of AI, so making the contest unrated would feel like applying an ex post facto law.↵
Therefore, my current plan is as follows:↵
↵
- Keep this contest rated (and count GP30 scores).↵
- Ban AI for future AGC contests.↵
- Hold more AGCs to mitigate the effects of this incident.↵
↵
To realize the third point, I have to reconsider the style of AGC.↵
I'm not exactly sure about what changes to make, but one possible idea is to make a contest that is somewhere between ARC Div.1 and the current AGC.↵
↵
Again, this is entirely my mistake and I sincerely apologize to all participants.↵
I would also like to express my deepest gratitude to everyone who participated in this contest under such circumstances.↵
↵
AGC admin,↵
maroonrk↵
↵
[original post on AtCoder](https://atcoder.jp/posts/1564)
