Recently, we’ve run into an unpleasant situation: some large companies have been using a huge number of accounts to submit AI-generated solutions purely for model training, which ended up causing serious “in queue” congestion for everyone else.

Maybe it’s time to consider restricting submissions from unrated users.

If those AI-driven accounts were required to participate in at least one contest before being allowed to submit normally, it would drastically cut down the number of accounts they could abuse. On top of that, we could improve AI-detection during contests and apply stricter monitoring to accounts that submit massive amounts of AI-generated code.

For regular users, the requirement is trivial — just join a single Codeforces round, and you’re good to go. Compared to the awful experience of having the queues jammed for hours, this small inconvenience might be a reasonable trade-off.

That’s the best idea I can think of at the moment. What do you think? How can we better protect the platform from such exploitative behavior?

Update：ig RainRecall's idea is much better

Perhaps assigning a separate evaluation machine specifically for Unrated Users would be a better approach.

If we group users by rating and let each group’s judges prioritize submissions from that group (only taking others when they’re idle), it should significantly reduce the load and help alleviate the issue.

My approach is this: fix the parameter $$$x$$$ from the problem statement and forbid the largest $$$y$$$ elements from participating in any operations. In other words, after removing those $$$y$$$ largest numbers, choose the largest $$$\frac{x+1}{2}$$$ numbers among the remaining elements to contribute to the medians, then perform the allowed operations sequentially from the smallest remaining numbers toward the larger ones until you exhaust the number of operations. Let $$$f(x,y)$$$ denote the maximum sum obtainable by this strategy.

Next I conjectured that for fixed $$$y$$$, letting $$$g(x)=f(x,y)$$$, the function $$$g$$$ is unimodal. It seems to hold on small examples, but when I submitted I got Wrong answer on pretest 4.

It looks like the unimodality property was wrong, so I instead fixed $$$x$$$ and conjectured that $$$g(y)=f(x,y)$$$ is unimodal,I submitted another modified version of the code and received Wrong answer on pretest 8.

Just when I didn't know how to debug, a magical idea popped up: concatenate two implementations and take the maximum of their outputs.

That's too crazy — you know, I concatenated two approaches that were both known to be wrong, yet in fact, it actually passed the problem.

ig my method can be easily falsified, but I still want to collect hacks here — I hope some contestants can hack this code so the problem's tests get stronger.

new submission