Proof_by_QED's blog

Codeforces Round 998 (Div. 3)
By Proof_by_QED, 6 weeks ago, In English

Hellowo Codeforces o7

cry, larush, chromate00, LMeyling, Lilypad, and I are ebullient to welcome you to participate in Codeforces Round 998 (Div. 3) at Jan/19/2025 17:35 (Moscow time). We have cooked up $$$7$$$ problems to be solved in $$$2$$$ hours and $$$30$$$ minutes.

The round will be hosted by rules of educational rounds (extended ICPC). Thus, solutions will be judged on preliminary tests during the round, and after the round, it will be a 12-hour phase of open hacks. After open hacks all accepted solutions will be rejudged on successful hacks.

Note that the penalty for each wrong submission in this round is 10 minutes. Also, note the rule restricting AI use!!! If you are caught using AI in an unorthodox manner, you will be banished off the face of the earth (trust me).

Remember that only the trusted participants of the third division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as a trusted participant of the third division, you must:

  • take part in at least five rated rounds (and solve at least one problem in each of them)
  • do not have a rating of 1900 or higher at any moment in time.

Regardless of whether you are a trusted participant of the third division or not, if your rating is less than 1600, then the round will be rated for you (unless you register unrated).

We would like to orz the following individuals for making the contest possible:

UPD: Editorial

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5 weeks ago, # |
  Vote: I like it +11 Vote: I do not like it

As a tester, I cannot confirm the word ebullient comes from ef: a fairy tale of the two.

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5 weeks ago, # |
← Rev. 4   Vote: I like it +4 Vote: I do not like it

I want to attend it and make some problems!

And slove $$$5$$$ problems (in this contest) !

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5 weeks ago, # |
  Vote: I like it -42 Vote: I do not like it

Learn to count please, codeforces has already hosted exactly 1950 rounds at the time this comment is written.

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    5 weeks ago, # ^ |
      Vote: I like it +9 Vote: I do not like it

    Maybe the author's meaning is there will be $$$1000$$$ Codeforces Round.

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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

How many problems are geometry?

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    5 weeks ago, # ^ |
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    I don't think it's good to publish the kind of the problems.

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    5 weeks ago, # ^ |
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    0<=n<=69, where n = number of geometry problems

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    5 weeks ago, # ^ |
    ← Rev. 2   Vote: I like it +21 Vote: I do not like it

    There are at least $$$\displaystyle{\int_{-2025}^{2025} \frac{x^{2025}}{x^{2024}+1} \mathrm{d}x}$$$ geometry problems.

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      5 weeks ago, # ^ |
      ← Rev. 3   Vote: I like it 0 Vote: I do not like it

      Human Language : There are no geometry problems (trust me)

      btw use \displaystyle

      nice

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        5 weeks ago, # ^ |
          Vote: I like it +3 Vote: I do not like it

        Human language: there are at least zero geometry problems

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          5 weeks ago, # ^ |
          ← Rev. 2   Vote: I like it 0 Vote: I do not like it
          $$$0 \le \displaystyle \int_{-2025}^{2025} \frac{x^{2025}}{x^{2024}+1} \: \text{dx} \le \infty$$$

          This is Proof by QED

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      5 weeks ago, # ^ |
      ← Rev. 2   Vote: I like it +2 Vote: I do not like it

      for anyone wondering f(x) = -f(-x) so the integration is 0 because the limits are symmetric along the y axis too

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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

As a tester, wishing you all positive delta! Alternatively, wishing you all positive (insert your favorite letter of the Greek alphabet, or any alphabet). Whatever floats your boat.

P.S. Would advise against getting banished off the face of the earth. Sounds unpleasant.

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5 weeks ago, # |
  Vote: I like it +7 Vote: I do not like it

as a testuwuer, very sigma contest

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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

hope that F is not hackable

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5 weeks ago, # |
  Vote: I like it +4 Vote: I do not like it

Fire in the holeee

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    5 weeks ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    WATER ON THE HILL

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      5 weeks ago, # ^ |
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      Wind from the Landscape

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        5 weeks ago, # ^ |
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        The echoes of three elements... They filled you with determination.

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    5 weeks ago, # ^ |
      Vote: I like it +8 Vote: I do not like it

    ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢠⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢸⣿⣦⣄⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢸⣿⣽⣻⣷⣤⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢸⣿⢾⣟⡷⣿⢿⣦⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣾⣟⣯⣿⣽⢯⣟⡿⣿⣦⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣿⡿⣟⣻⢿⣿⣟⡿⣧⣿⣿⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⣤⠀⠀⠀⠀⠀⠀⠀⢀⠀⠀⢀⣼⣿⣟⡿⡜⣭⢻⣾⡿⣽⡾⣽⢿⣆⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⣰⣿⡄⠀⠀⠀⠀⠀⢠⣿⣿⢿⡿⣟⣷⣿⣱⣛⣬⠳⡽⣿⣯⣟⣯⣿⣿⡆⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⢠⣾⣿⣿⠁⠀⠀⠀⠀⢠⣿⡿⣽⣯⢿⣻⣾⢧⢳⣜⡲⢏⡳⡽⣷⣿⡿⣷⣿⣿⡀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⡀⣿⣿⣽⠏⠀⠀⠀⠀⠀⣿⡿⣽⣷⣻⣟⣿⡱⣎⡗⢮⡵⣋⢷⣩⢿⣿⣿⣽⣿⣿⡇⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⢿⣿⡿⠋⠀⠀⠀⠀⠀⣸⣿⣻⣽⡾⣷⡟⢶⣙⠶⣩⢗⡺⢭⡖⡳⣎⣿⡿⣿⣻⢾⡇⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠛⠉⢈⠀⠀⠀⠀⠀⠀⣿⡿⣽⣳⣿⡟⣼⢣⢏⡾⣱⢫⡵⢫⣜⡳⢵⣺⣿⢷⣻⣿⡇⠀⠀⠀⣀⠀⠀⠀ ⠀⠀⠀⢀⣾⠀⠀⠀⠀⠀⢰⣿⢿⡽⣷⡿⣜⡖⣫⠮⡵⣣⠯⣜⡳⣎⢽⣚⢼⣿⣻⣽⣾⣇⠀⠀⠀⣸⡄⠀⠀ ⠀⠀⣠⣿⣿⡇⠀⠀⠀⠀⢸⣿⢯⣿⣿⡱⢞⡼⣱⣋⢶⡭⢷⡹⣜⡎⣗⠮⣽⣿⢯⣷⢯⣿⢦⣀⣴⣿⣿⡄⠀ ⠀⢰⣿⣟⣾⣷⡀⠀⠀⠀⣸⣿⣻⣾⢧⣛⡭⡖⣧⡿⠋⠀⢸⡱⢮⡹⡼⣹⢾⣿⢯⣟⣯⣿⣻⣟⣯⣷⢿⣷⠀ ⠀⣿⣟⣾⢷⣻⢿⣶⣶⣾⡿⣯⣷⡿⣲⡍⣶⡽⠋⠀⠀⠀⢸⣱⢫⠵⣓⢧⣿⣿⣻⡽⣷⢯⣷⢿⣽⢾⣯⢿⡇ ⢸⣿⣻⡾⣟⣯⣿⣞⣷⢯⣿⣳⣿⡗⢧⣞⡽⠁⠀⠀⠀⠀⢸⢧⢏⡻⣜⣣⢻⡿⣷⠿⣿⢻⣿⣻⡾⣿⣽⣻⣿ ⣽⣿⣳⡿⣿⣛⣷⣿⡾⣿⣽⣿⢿⣞⡱⣾⠁⠀⠀⠀⠀⠀⢸⣏⠾⣱⢣⡝⡶⣹⢌⡳⢼⣣⣿⡿⣽⡷⣯⣷⣿ ⠸⣿⣳⡿⣿⡳⣜⢎⣟⡻⢯⣤⠟⣡⣿⡇⠀⠀⠀⠀⠀⠀⠀⣯⣏⡳⢽⡸⣵⢫⡷⣭⢳⡼⣿⡿⣽⣻⢷⣻⣾ ⠀⢿⡿⣽⣿⡷⣩⢞⣬⠳⣍⡳⢞⡽⣿⠁⠀⠀⠀⠀⡦⡀⠀⠻⣾⣽⠮⠛⢁⣾⡝⡖⣧⣿⣿⡽⣿⣽⣻⢿⠃ ⠀⠊⣿⣟⣾⣷⡹⢎⡶⣛⡼⣩⣟⢲⣿⡀⠀⠀⠀⣸⠀⢧⠀⠀⠀⠀⠀⢀⣾⣧⢻⡜⣾⢿⡷⣿⣷⡿⣽⠏⠀ ⠀⠀⠊⣿⣯⣿⣵⢫⣶⢹⡜⣷⠉⠛⠋⠁⠀⠀⢠⡇⠀⠈⡇⠀⠀⠀⠀⠘⠁⣿⠓⣾⢱⡞⣼⣿⣯⣿⠋⠀⠀ ⠀⠀⠀⠈⠻⣿⣷⡭⣲⢫⢵⣻⡀⠀⠀⠀⠀⠀⡾⠀⠀⠀⠹⣄⠀⠀⡀⠀⢸⣏⠷⣎⡳⣾⣿⣿⠞⠁⠀⠀⠀ ⠀⠀⠻⣤⣀⠈⣻⣷⣭⢳⡣⡟⣧⠀⠀⡎⠑⠚⠁⠀⠀⠀⠀⠈⠙⠉⢡⣶⡿⣜⢫⣖⣿⣿⠋⠁⣠⡀⠀⠀⠀ ⠀⠀⠀⠘⠻⣿⣿⢿⣿⣧⣳⡝⡽⣆⠀⢳⡀⠀⠀⠀⠀⠀⠀⠀⠀⢠⣯⣿⠱⣎⣷⣿⡿⣿⢿⡿⠋⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠈⠛⢿⣾⣻⣿⣾⡳⣽⣧⡀⢳⡀⠀⠀⠀⠀⠀⠀⢠⣿⣟⣬⣿⣿⢿⣽⣻⠟⠉⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠉⠛⠿⠿⣷⣽⣻⣦⠙⢤⡀⠀⠀⠀⣠⣿⣿⣾⣿⠿⠟⠋⠉⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠉⠉⠉⠛⠉⠁⠀⠈⠉⠉⠁⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀

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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

hope i will become specilist in this contest

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    5 weeks ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    div2s are better for becoming specialist imo if you solve 3 you gain heavy delta

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      5 weeks ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      Agreed.

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        5 weeks ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        Is expert possible without solving div2D?

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          5 weeks ago, # ^ |
            Vote: I like it 0 Vote: I do not like it

          If C's like 1600, then there might be a chance if you solve C under 1 hour, because then your rank will be around 1000. Otherwise I think we must solve D to reach expert.

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            5 weeks ago, # ^ |
              Vote: I like it 0 Vote: I do not like it

            D is a bit hard for now (for me)

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              5 weeks ago, # ^ |
                Vote: I like it 0 Vote: I do not like it

              For me too, but let's hope one day we'll be able to solve it.

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5 weeks ago, # |
  Vote: I like it +6 Vote: I do not like it

Will it use modulo 998 244353?

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5 weeks ago, # |
  Vote: I like it +17 Vote: I do not like it

geometry dash div3 right after geometry dash div4???

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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

As a tester army-man, uwu contest!

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5 weeks ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

Hoping to reach Cyan back !! Wish me luck..

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5 weeks ago, # |
  Vote: I like it +3 Vote: I do not like it

As a gd player, I can confirm this is good

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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

I want to ask that what is penalty for 1 minute.

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5 weeks ago, # |
  Vote: I like it +3 Vote: I do not like it

I don't have chromate00's ship yet :(

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5 weeks ago, # |
  Vote: I like it +8 Vote: I do not like it

GeometryDashforces

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5 weeks ago, # |
  Vote: I like it +3 Vote: I do not like it

gd mentioned letsgooooooo

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5 weeks ago, # |
  Vote: I like it -30 Vote: I do not like it

Proof_by_QED sorry but i will use AI to make sure that we are safe trust me

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5 weeks ago, # |
  Vote: I like it +13 Vote: I do not like it

As a tester I can confirm the round exists.

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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

Pupil this time?

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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

omg another cry round orz

JeffLegendPower sends his regards

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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

I want to ask that a programmer with rating 1000 can solve how many problems? and also what is the penalty for 1 minute.

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    5 weeks ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Typically 2 or 3 problems in div3s have difficulty <=1000. To be honest, though, I wouldn't advise you to try to predict how many problems you'll solve in a contest before it starts. (Thinking you've reached your limit and solved everything you could have solved might affect your performance, even if you still try to solve the next problem)

    The penalty is the sum of minutes plus 10 for each wrong submission, so the penalty for each minute is 1.

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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

As a gd player, contest based on Geometry Dash? :D

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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

id 114184865

Can any omega-sweat tell me how hard this might be thank you <3 <3

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    5 weeks ago, # ^ |
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    i have no idea how to get past 3%

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      5 weeks ago, # ^ |
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      you have to double click the yellow orb

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5 weeks ago, # |
  Vote: I like it +3 Vote: I do not like it

A fellow scissors ship enjoyer?? 😱😱😱😱

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5 weeks ago, # |
  Vote: I like it +14 Vote: I do not like it

POV: codeforces when im trying to stop being addicted to gd

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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

I think this intersects with MITIT.

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    5 weeks ago, # ^ |
      Vote: I like it +6 Vote: I do not like it

    This only intersects with round 1 of advanced. Beginner round is much later after this contest ends.

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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

As a tester, ratio the blog by upvoting my comment

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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

As an alien, I can confirm that this round will be from out of this world.

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5 weeks ago, # |
  Vote: I like it +1 Vote: I do not like it

And You for participating! Why is this line missing from blog?

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5 weeks ago, # |
  Vote: I like it +3 Vote: I do not like it

Again!! If I don't become specialist in this contest then I'll

Spoiler
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5 weeks ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

My Goal for This Contest

Spoiler
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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

please like

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5 weeks ago, # |
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I was NOT expecting Geometry Dash in the thumbnail. Looking forward to this contest!

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5 weeks ago, # |
  Vote: I like it +4 Vote: I do not like it

As a participant, it is going to be my first unrated div. 3 :)

I hope cry doesn't make rated participants :'(

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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

I hope this round will be mine and able to solve at least 3 questions or more .... BTW WHT DO YOU THINK GUYS WHAT IS THE LEVEL OF CONTEST WILL GOING TO HAPPEN??

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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

To solve last problem I need to beet Tidal Wave?

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5 weeks ago, # |
← Rev. 4   Vote: I like it +1 Vote: I do not like it

"do not have a rating of 1900 or higher at any moment in time."

Did we change Div-3 limit to 1900 ? Proof_by_QED

UPDATE: Got confused between Trusted participants and Rated Participants

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    5 weeks ago, # ^ |
      Vote: I like it +4 Vote: I do not like it

    that is the limit for trusted participants. it means that anyone who had hit 1900 at least once will not be shown in trusted standings.

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      5 weeks ago, # ^ |
      ← Rev. 3   Vote: I like it +1 Vote: I do not like it

      UPDATE: Got confused between Trusted participants and Rated Participants

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        5 weeks ago, # ^ |
        ← Rev. 3   Vote: I like it +4 Vote: I do not like it

        Because this rule precisely exists to combat against higher rated people unduly dropping rating and "bullying" lower educational divisions in order to boast an "achievement"?

        Please do read the line (already exists in announcement, copypasted for you):

        Regardless of whether you are a trusted participant of the third division or not, if your rating is less than 1600, then the round will be rated for you (unless you register unrated).

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          5 weeks ago, # ^ |
            Vote: I like it +5 Vote: I do not like it

          I am sorry, I misread. I didn't differentiate between "Trusted participant" and "rated participants".

          Thanks for clarifying.

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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

Hope to get to pupil!

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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

has the difficulty increased due to ai use?

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5 weeks ago, # |
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Hope that I can become Pupil again :)

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5 weeks ago, # |
  Vote: I like it +1 Vote: I do not like it

How do I register unrated? Doesn't seem to be possible.

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    5 weeks ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    Should be enabled now, thanks for pointing it out!

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5 weeks ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

hope to expert (0^0).

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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

hope to become grandmaster in this round...

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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

Hopefully I can become an Expert through this contest.

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5 weeks ago, # |
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This is will be my first round on codeforces, good luck to me) and to you, guys)

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5 weeks ago, # |
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It's a bad day for me when I get a -150 delta :sob:

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5 weeks ago, # |
  Vote: I like it +5 Vote: I do not like it

Abhishek_Srivastava Orz

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5 weeks ago, # |
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If i don't become cyan

Spoiler
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5 weeks ago, # |
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Best Div3 contest till now... so much to learn >>>

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5 weeks ago, # |
  Vote: I like it +6 Vote: I do not like it

formula for problem F

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    5 weeks ago, # ^ |
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    agh, I knew there would be some formula I didn't know in order to compute this efficiently...

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    5 weeks ago, # ^ |
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    Can it be solved using the formula $$$1^k + 2^k + 3^k + .... n^k$$$ ?

    where K = sum of power of prime divisors.

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      5 weeks ago, # ^ |
        Vote: I like it +3 Vote: I do not like it

      No. For x = 4 and n = 3, this formula outputs 14 but 10 is the right answer (this case is already included in the samples).

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5 weeks ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

The one thousand rating question: What is wrong with my problem E?

Tried: sort, two pointers, binary search... nothing work... (*desperate*)

Or did I read the problem wrong?

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5 weeks ago, # |
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Is E DSU?

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    5 weeks ago, # ^ |
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    yes

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      5 weeks ago, # ^ |
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      Got the answer 1 min after the contest. RIP huge delta loss

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    5 weeks ago, # ^ |
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    No, I solved this problem without DSU, just a couple of DFS.

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    5 weeks ago, # ^ |
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    Not necessarily. At least I used dfs and dfs only. I found all the components in the second graph and deleted such edges from the first graph, that connect $$$(u, v)$$$ from different components. Then I just calculated the amount of components $$$A$$$ in the first graph and the amount of components $$$B$$$ in the second graph, adding their difference $$$A - B$$$ to the answer.

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5 weeks ago, # |
  Vote: I like it +1 Vote: I do not like it

cute div 3...Thanks for the round.

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5 weeks ago, # |
  Vote: I like it +4 Vote: I do not like it

Happy to be first solve on G

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5 weeks ago, # |
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Can anyone provide a case where my code fails? 301882825

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5 weeks ago, # |
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F solution please

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5 weeks ago, # |
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My competitive programiness is degrading exponentially faster contest by contest. Great problem-set though. Had fun.

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5 weeks ago, # |
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best div3

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5 weeks ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

omg very fast editorial

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5 weeks ago, # |
  Vote: I like it +18 Vote: I do not like it

I'm unsure if ChatGPT degenerated or problem setter intentionally rejecting problems solvable by ChatGPT on testing however, it solved literally 0 problem which is quite unusual. quality contest desu better than most div2 imo. well done

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5 weeks ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

Although I was pretty slow, I liked the problems lol.

I was initially gonna use DSU with rollbacks for E, then realized I was being numb in the head.

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5 weeks ago, # |
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What a frequency contest

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5 weeks ago, # |
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could anyone solve E with frequency ? :)

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    5 weeks ago, # ^ |
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    what do you mean by frequency?

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      5 weeks ago, # ^ |
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      Count the appearance of ench edge in f and g , then print the sum of different edges

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5 weeks ago, # |
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in problem E i took it for granted that F and G has 1 component each initially

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    5 weeks ago, # ^ |
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    well then the answer is $$$0$$$ in every case

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      5 weeks ago, # ^ |
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      no i mean F has 1 component and G has 1 component. I don't say F and G are connected

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        5 weeks ago, # ^ |
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        if a graph has one component then there exists a path between every possible pair of vertices

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          5 weeks ago, # ^ |
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          Yea but you may have some vertices missing in G which is in F or vice versa

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            5 weeks ago, # ^ |
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            I didn't understand the problem that way.

            In both graphs there are exactly $$$n$$$ vertices numbered from $$$1$$$ to $$$n$$$.

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5 weeks ago, # |
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How on earth can 16k people solved B, and 17k solved C? Not saying these were too-tough, but this large number of solvers are unreal man!!

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5 weeks ago, # |
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Was F matrix exponentiation?

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    5 weeks ago, # ^ |
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    Nah, apparently there's a formula for summation of stars and bars over the range [0, n] containers.

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5 weeks ago, # |
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was it a rated contest?

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5 weeks ago, # |
← Rev. 3   Vote: I like it 0 Vote: I do not like it

[DELETED]

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5 weeks ago, # |
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My code for F got accepted after contest :( 301899886

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5 weeks ago, # |
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Can someone please help me with this? idk how is it failing this is B problem

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define eb emplace_back
#define mod 1000000007
 
// USE LONG LONG WHEREVER NECESSARY
// USE INPUT OUTPUT TO HELP YOU. IT MAY CONFUSE YOU AS WELL. SO DONT BE STUCK ON ONE APPROACH FOR LONG TIME.
// DONT BRUTE FORCE YOUR APPROACHES IN PAPER,USE INTUITION TO CHECK IF IT WORKS, IF IT DOESNT SEEM LIKE IT, MOVE ON TO NEXT APPROACH
 
 
 
 
void solve()
{
  int n,m;
  cin >> n >> m;
  vector <vector<int>> arr(n);
  map <int,int> x;
  for(int i=0;i<n;i++)
  {
    for(int j=0;j<m;j++)
    {
      int a;
      cin >> a;
      arr[i].eb(a);
      x[a]=i+1;
    }
    sort(arr[i].begin(),arr[i].end());
  }
  vector <int> ans;
  vector <int> store;
 
    for(int i=0;i<n;i++)
    {
      store.eb(arr[i][0]);
    }
    sort(store.begin(),store.end());
   for(int j=0;j<m;j++)
   {
    vector <int> check;
    for(int i=0;i<n;i++)
    {
      check.eb(arr[i][j]);
    }
    sort(check.begin(),check.end());
    for(int i=0;i<n;i++)
    {
      if(x[check[i]]!=x[store[i]])
      {
        cout << -1 << endl;
        return;
      }
    }
   }
   for(int i=0;i<n;i++)
   {
    cout << x[store[i]] << " ";
   }
   cout << endl;
  
   } 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
int main()
{
 
  int t;
  cin >> t;
  while(t--)
  {
     solve();
  }
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    5 weeks ago, # ^ |
    ← Rev. 3   Vote: I like it 0 Vote: I do not like it

    you're not updating your map x to get the permutation.

    take store as vector of pair of integers

    vector<pair<int, int>> store;
//store[i].first = the value of the card which it will sort by
//store[i].second = cow no. which will tell u the permutation after sorting

    also, instead of running another loop for check u can simulate the game directly

    here is my submission for ref https://codeforces.me/contest/2060/submission/301905850 (I used the same method)

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      5 weeks ago, # ^ |
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      actually i figured it out , my if condition to return -1 is missing a key detail, the first element of the jth column should be greater than last element of the j-1(th) column, so basically update last element as i move across the columns

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5 weeks ago, # |
← Rev. 3   Vote: I like it 0 Vote: I do not like it

difficulty lvl (imo) — E>B>C>D>A

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    5 weeks ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    indeed, B was like a Div2 B.

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    5 weeks ago, # ^ |
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    I think for ICPC-style contests, it's reasonable to have problems shuffled randomly. I think it would be more fun that way, it's up to each contestant to identify which problem is easier.

    (It's just that people are so used to Codeforces problemsets having increasing difficulty starting from A and so it's like an unspoken "rule" that it should be that way).

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5 weeks ago, # |
← Rev. 6   Vote: I like it +5 Vote: I do not like it

My solution for F.

Let $$$f(a,\ n)$$$ the number of ways to make an array with product $$$a$$$ and $$$n$$$ elements. We need to find $$$F(a,\ n) = f(a,\ 1) + f(a,\ 2) + ... + f(a,\ n)$$$ Using combinatorics arguments, $$$F(a,\ n)$$$ for the first element is some divisor $$$d$$$ of $$$a$$$, and the other elements can be choose in $$$F(a/d,\ n-1)$$$ ways. we need to consider the case when the array is {$$$a$$$}, so add 1 to the result $$$F(a,\ n) = 1 + \sum_{d|a} F(d,\ n-1)$$$

Using the definition for $$$F(a,\ n)$$$ for $$$2a$$$ and $$$n+1$$$, we have 2 equations

$$$F(2a,\ n+1) - 1 - \sum_{d|2a, d \ne a, d \ne 2a} F(d,\ n) - F(2a,\ n) = F(a,\ n)$$$

$$$F(2a,\ n+1) - F(2a,\ n) - f(2a, n+1) = 0$$$

Subtracting:

$$$F(a,\ n) = f(2a,\ n+1) -1 - \sum_{d|2a, d \ne a, d \ne 2a} F(d,\ n)$$$

Calculate $$$f(2a, n+1)$$$ is easy, we just need to find $$$2a = p_1^{a_1}\cdot p_2^{a_2} ...$$$ and multiply $$$\binom{n + a_1}{a_1} \cdot \binom{n+a_2}{a_2} ...$$$

And all divisors of $$$2a$$$ except $$$a$$$ and $$$2a$$$ are smaller than $$$a$$$, so we're done 301902082

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5 weeks ago, # |
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Judging by number of submissions A=B=C=D. Rename Codeforces to Cheatforces

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    5 weeks ago, # ^ |
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    E >>>> B > D > C >> A

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      5 weeks ago, # ^ |
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      As a tester, I thought E was easier than D which was easier than C...

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        5 weeks ago, # ^ |
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        Most people dont know how to use DSU.

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          5 weeks ago, # ^ |
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          You didn't need DSU, a DFS / BFS solution works as well; with that being said, I don't personally think E was easier than D

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        5 weeks ago, # ^ |
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        bruh how is a DSU problem (E) easier than a frequency array problem (C)?

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          5 weeks ago, # ^ |
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          Because if you know what a DSU is it's immediately obvious how to solve the problem. With C I actually had to use my brain for a nonzero amount of time.

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            5 weeks ago, # ^ |
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            You are right in a sense, but more people know Frequency array than DSU.

            I'd say we're both correct in a different sense.

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    5 weeks ago, # ^ |
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    In my opinion, this isn't horribly off, B and C were similar difficulty (with B being a bit harder), and D was easier than most other div3 Ds (and even if you couldn't figure it out, the greedy solution wouldn't be too difficult to guess). Additionally, D has 10k less correct submissions than A, so I don't know where you are getting that from.

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5 weeks ago, # |
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Made the stupidest mistake writing the binary search for C and couldn't identify it in time. Day (night) ruined.

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5 weeks ago, # |
  Vote: I like it +10 Vote: I do not like it

I tried many hacking, and CF site says "Rate limit exceeded" ... (I saw this first time)

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    5 weeks ago, # ^ |
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    you hacked problem d so many time , is there any fault in question ?

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    5 weeks ago, # ^ |
    ← Rev. 2   Vote: I like it +16 Vote: I do not like it

    They recently changed the policy on viewing submissions. Now we don't have that unreasonable cool down time for each submission, and instead we get that "rate limit exceeded" after dozens of submission views in a short time, and it lasts for like an hour. It's still too harsh for people who want to hack a lot, but I guess it works for most people for now...

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5 weeks ago, # |
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If you look at the first 2 submission of b you can see 2 identical submissions with comments in french that scream chatgpt, dont know where to say it so i put it here, i suppose there are more like this

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5 weeks ago, # |
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solved D after contest :( Got stuck on C at least I managed A, B, C

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    5 weeks ago, # ^ |
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    same..W T F I couldn't solve D on contest time

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5 weeks ago, # |
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it is contest 5 problem solve

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5 weeks ago, # |
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Problem F and its solution is just absolute beauty. Nice problem.

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5 weeks ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

I registered as rated, why it's marked as unrated now?

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5 weeks ago, # |
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Why is the contest unrated? Wuwuwu(╥_╥)(╥_╥)

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5 weeks ago, # |
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I am unrated at codeforces and wanted to get a rating so i participated in this contest, but it still shows me unrated, why?

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    5 weeks ago, # ^ |
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    it will get updated for div3/div4 rating update takes 1 day atleast

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5 weeks ago, # |
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And this is how I lost 100 rating. nice

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5 weeks ago, # |
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I just could solve 1 problem

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5 weeks ago, # |
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Can anyone help me? As per the rules of this round, only trusted participants from the third division will be included in the official standings table.

Since I am a newbie here (having participated in only two rated contests so far), was this contest rated for me or not?

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    5 weeks ago, # ^ |
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    Yes, its rated regradless of being a trusted or non trusted participant if you are below 1600...

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5 weeks ago, # |
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how much time does it take to have the rating updated after the contest? For me the rating didn't update as of yet.

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5 weeks ago, # |
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why my answers deleted and i dont get rating

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4 weeks ago, # |
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Please don't deduct my rating, its already very less. Similarity of code is a coincidence.

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4 weeks ago, # |
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Hello Contest setters i have been using ideone.com for a while now and for that reason system gave a messsage that my solution matched with other people whom i dont even know ,can you please look into this .Thank you

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    4 weeks ago, # ^ |
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    Also im new to cf so i didnt know about an original post by Mike about not using ideone.com .I promise that i will switch to some other IDE

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4 weeks ago, # |
  Vote: I like it -8 Vote: I do not like it

"I’d like to address the skipped submissions in this contest. I admit I copied the solution for Question B, and that was a mistake. However, for the other three questions, I wrote the code myself. MikeMirzayanov Vladosiya could you kindly review my submissions? I deeply regret my mistake and want to clarify my intent. Apologies for any inconvenience caused."

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3 weeks ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

hey there , my account got banned for the using of AI, i didnt have a clue regarding the rule, ill follow it from now on, is there anyway i can get my account activated again??

the username was Moayad999

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