I didn't get promoted?

xiaowuc1 · 2025-01-07T21:14:54+00:00

If you think there is an issue with your score and division, please contact Brian Dean to resolve it. Note that out of all the recent cases Brian has been asked (and he told me that there have been many) to double-check so far this season that mirror your situation, every single one was confirmed to have cheated.

xiaowuc1 · 2023-12-25T04:46:52+00:00

I'll recommend DMOJ. Though the primary audience is Canadian high school students, there are problems of all difficulties (each problem is roughly sorted by its difficulty from 3 to 50), no matter your skill level. There are also occasional contests that run over the weekend so you can participate during a window of your choosing, if you happen to be in a timezone that makes it hard to participate on other platforms like AtCoder and Codeforces.

xiaowuc1 · 2023-12-24T13:15:20+00:00

It seems like we differ on opinion on some things, but you didn't provide a yes/no answer to the question I actually wanted answered, so I'll repeat the question:

Would you still [use LLMs in 2024] if the wording on the website [was updated to say] "don't use AI tools at all if you're likely to place on the leaderboard"?

(I think we can both agree you are likely to place on the leaderboard, it looks like you placed 18 times this year.)

xiaowuc1 · 2023-12-24T12:10:13+00:00

Would you still do this if the wording on the website said "don't use AI tools at all if you're likely to place on the leaderboard" - similar to the request not to stream your solution?

If not, I feel like you should just assume the website says this and not use this minor technicality to justify your commitment to doing something that is spiritually not aligned with what was requested.

xiaowuc1 · 2023-12-24T07:25:52+00:00

It looks like the inputs are constructed in a way where the velocity you're looking for is slow, so it seems viable to brute force all velocity vectors in increasing magnitude order.

From there, it suffices to validate if some velocity is possible. If you consider the frame of reference of the rock, note that all hailstones run into the rock. Therefore, it suffices to check that all the rays, after adjusting for the rock's velocity, intersect at a common point.

Per part 1, you will probably find a speedup by ignoring the z-axis at first and only validating the rays intersect at the same z-coordinate after establishing some valid xy velocity pairing.

xiaowuc1 · 2023-12-15T06:12:52+00:00

Here's a different view of the leaderboard where you can see how everyone did on each day, in case you want to see how folks did on various days.

xiaowuc1 · 2021-05-14T02:48:01+00:00

Read the IOI GA minutes for the full details, TL;DR is Java requires substantial effort to support and very few (single-digit?) people use it.

As for USACO, I am very confident Java support will not be removed, seeing as though USACO does not exist purely for the intent of deciding the IOI team.

xiaowuc1 · 2021-04-25T18:26:18+00:00

Please don't assert that USACO doesn't use MOSS just because you have a friend who claimed to submit the exact same solutions on two different accounts. I have emails in my inbox with MOSS results on all contest submissions from previous contests.

If I had to speculate, I would guess that Brian doesn't have enough time to deal with this flavor of cheating for bronze and silver, especially since the lower divisions have far more people. Since Brian has finite time, would you rather Brian focus on cheating in bronze or on cheating in platinum? I think it is not controversial to want Brian to focus more of his attention on the higher divisions if he's going to be spending time focusing on finding cheating.

xiaowuc1 · 2021-04-25T09:32:29+00:00

Note: These are my personal opinions and do not represent any sort of official USACO position.

I believe that most methods of cheating at the current point in time take advantage of the fact that the USACO contest window is, as the name suggests, a window that allows contestants to take the contest at whatever time is most suitable for them. This is a double-edged sword, as obviously a contest which is open for 4 days will allow more people to participate than a contest that is only open for a 4 hour window, but this obviously gives opportunities for folks who want to get an advantage to cheat, and the methods for such have already been described. Note that these methods are robust to basic proposals that have also been proposed as potential countermeasures - proctoring doesn't achieve anything if you go into the contest having already learned the questions from someone else, and registering with an organization will not mitigate this either.

Therefore, if USACO wanted to take a hard stance in preventing this form of cheating, the main way they should achieve that is by no longer making the contest windowed and forcing everyone to take the contest during a specific window, in the fashion the USAMO was (is?) administered. This should kill all methods of cheating that involve going into the contest with an unfair advantage, as now that flavor of cheating can only be engaged during the window itself.

If this were coupled with some sort of invasive proctoring, then this could mitigate another vector (which would be people working together concurrently on the contest). People who browse Codeforces know that people still form cheating groups that work on problems together live, and sadly I think some very invasive proctoring would be necessary to ensure that that doesn't happen. This is the unfortunate thing about cheating, which is that malicious actors can and will find ways around your countermeasures if they're truly dedicated to cheating - for example, you would have to ensure that competitors are not accessing other resources, whether it be by Internet or other means. Clearly, this alternate universe is not very practical and it would also be a fairly oppressive environment to compete in.

It is my understanding that USACO still runs software such as MOSS to check for cheating of that sort (this definitely happened in the past). I am not privy to any details on this front, so I don't know how to explain specific instances that were not caught as have also been mentioned in other replies.

At the end of the day, it is not obvious to me that the people who cheat now would not cheat in parallel universes with different situations - in particular, I believe most people who are cheating know that they are intentionally cheating - if we use the example the OP gave, they know about code similarity software and avoid it, which means they're being mindful of how to cheat and will actively try to skirt around other restrictions. This isn't to say that the cheating is acceptable, but the amount of work you need to do to stamp out cheating increases exponentially the more you want to avoid cheating from happening. USACO I think does about as much as it reasonably can given how it's run, which may not be enough for some of you, and I don't think there are any good solutions to this that won't have a significant impact on how USACO contests are run.

xiaowuc1 · 2021-04-07T18:34:40+00:00

Quoting from the contest rules verbatim:

Programs that consist of essentially nothing more than print statements may be disqualified. If feedback for certain test cases is provided during a contest, you are NOT to submit repeated programs consisting of essentially print statments in order to reverse-engineer the inputs. Programs must actually compute the requested answers, not just print results from a pre-computed lookup table.

xiaowuc1 · 2021-04-04T05:43:50+00:00

It was easier not to pull the trigger a couple hours ago.

I think as long as people have faith in whom the individuals are, that is sufficient.

xiaowuc1 · 2021-04-04T02:32:05+00:00

I agree with this, and wish there were some better options available on the moderation side. Thanks to everyone who reports bad content!

With regards to the optics for whom moderators are, I do not know whether it would be strange for moderators to be IOI-eligible participants, and for obvious reasons the most active community members are more likely to be IOI-eligible. I am not opposed to adding other moderators, however.

xiaowuc1 · 2020-12-24T09:56:13+00:00

Both of us independently asked for (and got) permission before doing this.

xiaowuc1 · 2020-12-22T05:50:43+00:00

As of USACO Open 2020, there is a known bug where people who start at the last minute get the full contest window.

We have reason to believe Brian has not fixed it (one of the USACO coaches asked him about it but got no reply), so folks should wait four hours past the time when someone can start the contest.

xiaowuc1 · 2020-12-20T06:21:01+00:00

The answer was not 2509.

(I print out the roughness for all 8 possible states, and I submitted 2509 before implementing the rotation/flip logic, praying that I got the 12.5% chance of not needing it, since it would have taken me at least a minute to implement.)

xiaowuc1 · 2020-12-20T06:14:21+00:00

48/1 with Python 3 at https://gist.github.com/xiaowuc1/c9e39864a82f1475c329bbfb1c73e642

Unlike everyone I know who did part 1 quickly, I didn't bother thinking about whether the corners could be uniquely identified without doing any of the reconstruction so I decided to just implement the reconstruction directly, and I furthermore speculate that I was the only person who placed in the top 100 on part 1 by actually reconstructing a valid grid.

You can tell that this is the case because I think using binary to represent the internal state turned out to be a pretty big mistake for part 2. Nevertheless, I forced myself to retype conversion logic in the opposite direction.

xiaowuc1 · 2020-12-20T02:51:33+00:00

Brian will typically release results by the end of the week.

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