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tianbu's blog

By tianbu, history, 4 weeks ago, In English
A Tutorial
A Code
B Hint 1
B Hint 2
B Hint 3
B Tutorial
B Code (Python)
C Hint 1
C Hint 2
C Tutorial
C Code
D Hint
D Tutorial
D Code (Python)
E1 Hint
E1 Tutorial
E1 Code
E2 Hint
E2 Tutorial
E2 Code

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By tianbu, history, 10 months ago, In English

I was trying to hack myself in D. It got hacked successfully, but when I resubmitted it, it still passes in 982ms. I was trying to generate a better test so that it definitely couldn't pass.

So I generated another test, and tried to hack, but the system return "Unexpected verdict". Do that mean the system is not working? Or the authors' solution is wrong? Or something else?

I told my friend tianxiawoyou and when he hacks me, the verdict is still "Unexpected verdict". I tried to hack another person, but it seems that the system is working.

Here is my generator (I tried both uploading the generator and the file, but both returns "Unexpected verdict")


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By tianbu, history, 11 months ago, In English

Hello Codeforces!

gyh20 and I are glad to invite you to Codeforces Round #670 (Div. 2) which will start on Sep/12/2020 16:45 (Moscow time). Note the unusual start time of the round.

The contest will last for two hours, and you will have five tasks to solve. The tasks are prepared by me and gyh20. This round is rated for participants whose rating is not higher than 2099. You can see that my current rating is exactly 2099 :)

There might be an interactive problem. You can learn about them here.

We would like to thank:

We tried our best to make the statements short and clear, pretests strong and problems interesting. We hope you like the problems!

Score distribution will be announced shortly before the round.

Good luck and have fun!

Upd: Score distribution is 500-750-1250-1750-2500.

Upd: For problem reasons, the contest is delayed for 10 minutes. We are very sorry to keep you waiting, sorry again.

Upd: Score distribution is changed to 500-1000-1500-2000-2750.

Upd: The round is finished. We're really sorry for B being well-known (none of the testers knew the harder version of this problem in ABC173E). Still, congratulations to the winners!

Div1 (unofficial):

  1. WZYYN
  2. Geothermal
  3. kort0n
  4. neal
  5. kotatsugame


  1. JSoap
  2. DemolitionLovers
  3. killyou
  4. gmh77
  5. WaterCrystal

Upd: Editorial is out here.

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