I've hacked all AC solutions of [this](https://codeforces.net/contest/1383/problem/F) problem, which were submitted during the contest, and I believe I can hack most of upsolving solutions.↵
Currently, I only checked that they time out on my local machine, because "Unexpected Verdict" prevents me from uphacking.↵
I even hacked model implementation in the editorial.↵
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[Here](https://ideone.com/cHvjkp)'s my latest generator. Feel free to challenge it.↵
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Side Note: [user:yosupo,2020-07-26] wrote a [solution](https://codeforces.net/contest/1383/submission/88036534), which passes the above case, but I failed it with another [generator](https://ideone.com/LKx3FP).↵
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What I want to argue is that TL of this problem is too tight, and it affected some of the competitors.↵
For example, I got almost the same idea as the model solution during the contest. Still, I was too scared to write it because I suspected it would time out without full optimization and possibly some tweaks like shuffling vertices/edges or contracting vertices.↵
As I proved it myself, my thought was correct.↵
However, this observation didn't help me, and some people who didn't think of this (or believed the weakness of the test) passed F, which seems unfair to me.↵
↵
I'm not saying the round should be unrated; I think there exists a really well-optimized solution that can pass all tests.↵
**But please, problem setters and coordinators, you should give careful consideration to TL of problems.**↵
**Don't set the TL by how fast your solutions run on your test.**↵
I wish future CF writes and coordinators read this, and that's the reason why I posted it as a separate blog, not a comment to the round.↵
↵
P.S. Please notify me when you believe your solution can pass all tests, I'll try to challenge it.
Currently, I only checked that they time out on my local machine, because "Unexpected Verdict" prevents me from uphacking.↵
I even hacked model implementation in the editorial.↵
↵
[Here](https://ideone.com/cHvjkp)'s my latest generator. Feel free to challenge it.↵
↵
Side Note: [user:yosupo,2020-07-26] wrote a [solution](https://codeforces.net/contest/1383/submission/88036534), which passes the above case, but I failed it with another [generator](https://ideone.com/LKx3FP).↵
↵
What I want to argue is that TL of this problem is too tight, and it affected some of the competitors.↵
For example, I got almost the same idea as the model solution during the contest. Still, I was too scared to write it because I suspected it would time out without full optimization and possibly some tweaks like shuffling vertices/edges or contracting vertices.↵
As I proved it myself, my thought was correct.↵
However, this observation didn't help me, and some people who didn't think of this (or believed the weakness of the test) passed F, which seems unfair to me.↵
↵
I'm not saying the round should be unrated; I think there exists a really well-optimized solution that can pass all tests.↵
**But please, problem setters and coordinators, you should give careful consideration to TL of problems.**↵
**Don't set the TL by how fast your solutions run on your test.**↵
I wish future CF writes and coordinators read this, and that's the reason why I posted it as a separate blog, not a comment to the round.↵
↵
P.S. Please notify me when you believe your solution can pass all tests, I'll try to challenge it.
