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DeadlyCritic's blog

Codeforces Round #652 (Div. 2)
By DeadlyCritic, history, 3 weeks ago, In English,
$$$~-\text{In the name of God}~-$$$

Hi community,

I'm glad to invite you to my first contest, Codeforces Round #652 (Div. 2) which will be held at Jun/23/2020 17:05 (Moscow time) ($$$\text{notice the unusual time}$$$). The problems are mainly prepared and invented by me. The round is rated for participants with rating strictly less than $$$2100$$$, others are able to take part in the round out of competition. You will be given $$$2$$$ $$$\text{hours}$$$ to solve $$$6$$$ $$$\text{problems}$$$.

Firstly I'd like to thank adedalic for coordinating and reviewing the round, as well as helping with many different things.

I'd like to thank antontrygubO_o, physics0523, McDic, Ashishgup, dannyboy20031204, Kuzey, Return_0, FieryPhoenix, ma_da_fa_ka, ITDOI, AM_I_Learning, pikmike, lynmisakura, JustasLe and ArimeZ for testing the round and giving valuable feedback.

Also I'd like to thank coauthors, amiralisalimi, AS.82 and davooddkareshki for helping me with inventing and choosing the problems.

Finally, thanks to MikeMirzayanov for very nice and convenient Codeforces and Polygon platforms.

I wish you all will find the problems interesting, thank you for participating, and good luck!

$$$\text{Scoring distribution : } \; 500 ~- 1000 ~- 1500 ~- 2000 ~- 2500 ~- 3000$$$

$$$\textbf{UPD}$$$ : Editorial is out

 
 
 
 
  • Vote: I like it
  • +1231
  • Vote: I do not like it

Comments Comments (397)
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3 weeks ago, # |
  Vote: I like it +55 Vote: I do not like it

An Iranian round after a long time .....
Thanks for your hard work.

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    3 weeks ago, # ^ |
      Vote: I like it +61 Vote: I do not like it

    Thanks, we'll see more Iranian rounds from now. :]

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      2 weeks ago, # ^ |
        Vote: I like it +199 Vote: I do not like it

      What matters to us is a codeforces round, whether it's Indian/Iranian/else. We love codeforces

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        2 weeks ago, # ^ |
          Vote: I like it +66 Vote: I do not like it

        I agree with this. People seem to be focusing too much on which country the problem setters are from, while they should be caring about the quality of the problems. There is absolutely no correlation between the ethnicity of the problem setters and the actual contest.

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          2 weeks ago, # ^ |
            Vote: I like it +41 Vote: I do not like it

          Its true. But these comments are mostly about finding someone you can relate to as the problem setter among the vast CF users. So there is no harm done.

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        2 weeks ago, # ^ |
          Vote: I like it -10 Vote: I do not like it

        True man

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

        Can't agree more with you nik. All that matters is the new question set : )

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        2 weeks ago, # ^ |
        ← Rev. 2   Vote: I like it -34 Vote: I do not like it

        Deleted

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          2 weeks ago, # ^ |
            Vote: I like it -7 Vote: I do not like it

          please focus on the rounds rather than who sets the problem that's none of our business we are just bunch of human beings that share the same love for coding !!

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            2 weeks ago, # ^ |
            ← Rev. 2   Vote: I like it -24 Vote: I do not like it

            Deleted

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

              so what lol just because I have a country name in my username doesn't mean I am those type of people who cares more about ethnicity or nationality when it comes to enjoying solving problems on codeforces !!

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3 weeks ago, # |
  Vote: I like it +338 Vote: I do not like it

I am an atheist.Can i participate in this round?

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    3 weeks ago, # ^ |
      Vote: I like it +224 Vote: I do not like it

    You welcome.

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    2 weeks ago, # ^ |
    ← Rev. 3   Vote: I like it -140 Vote: I do not like it

    LoL.

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      2 weeks ago, # ^ |
        Vote: I like it -140 Vote: I do not like it

      Congrats! For these downvotes :p

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    2 weeks ago, # ^ |
      Vote: I like it -102 Vote: I do not like it

    I hope that your question is not a way to make fun of author's faith. Cause I'm smelling something like that

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      2 weeks ago, # ^ |
      ← Rev. 2   Vote: I like it -91 Vote: I do not like it

      Really like to discuss the down voters. Why someone asks something like that? Can you see any kind of religion constraints in announcement or in CodeForces rules? Then let me know too!

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        2 weeks ago, # ^ |
          Vote: I like it +65 Vote: I do not like it

        You got downvotes because of a totally off-topic comment.

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          2 weeks ago, # ^ |
            Vote: I like it -19 Vote: I do not like it

          Was the original comment on-topic?

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          2 weeks ago, # ^ |
            Vote: I like it -11 Vote: I do not like it

          He got downvotes because he misinterpreted the essence of the question which boils down to the relevance of expression of faith in the contest announcement.

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

            ?

            Like, why are you answering yourself

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

              Guys may you tell me why someone should ask such question. Just your opinion. I mean the abhisar1414 guy

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

              Can't you figure out which comment answers what?

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

                They're on the same level..

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

                  There is a button on top for navigating to the parent comment.

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

                  Yes, that's how I know they're on the same level. Your two comments lead to the same comment.

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

                  Right, but didn't you say that I was answering myself?

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

                  Oh Ok. You should write them on one comment though.

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        2 weeks ago, # ^ |
          Vote: I like it -52 Vote: I do not like it

        Don't care about negative contribution. Improving rating should be main focus.

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

        The sentence about god was the irrelevant in the announcement. If it was not there, no one would have started this.

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

          Would any other kind of irrelevant sentence have provoked such a reaction?

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    2 weeks ago, # ^ |
      Vote: I like it +74 Vote: I do not like it

    Would you refuse to accept this?

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

    You might have been more comfortable if the entire phrase had been used: "In the name of God, the Most Gracious, the Most Merciful".

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    2 weeks ago, # ^ |
      Vote: I like it -7 Vote: I do not like it

    lol

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3 weeks ago, # |
  Vote: I like it +38 Vote: I do not like it

Ashishgup held three rounds and now he is a tester in this one. That's a lot of work.

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3 weeks ago, # |
← Rev. 4   Vote: I like it -72 Vote: I do not like it

Deleted

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

I am a beginner.Can any one give some advice about this contest.Please ,It will be helpful for me.

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    3 weeks ago, # ^ |
      Vote: I like it +24 Vote: I do not like it

    A — dificulty will be less than 1200 & B -will less than 1400 most of the time..practise those problem from problemset with those difficulties . I think it will help

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

      many many thanks for your advice.

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

      If you get stuck on these, read the editorials. They will give you an idea of the sorts of algorithms that you need for problems at this level.

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    2 weeks ago, # ^ |
      Vote: I like it -24 Vote: I do not like it

    On tuesday at the time of contest open codeforces and start solving some problems

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    2 weeks ago, # ^ |
    ← Rev. 2   Vote: I like it +42 Vote: I do not like it

    If it your first contest, don't worry if you don't solve much. Even as a very experienced programmer (40 years as a professional software engineer) it took me a few tries to get the hang of programming contests.

    Unless you are in the last couple of minutes of a contest, always try running the provided examples locally (or using "custom test") before you submit. On Codeforces you lose points for failed submissions.

    If you know more than one programming language use whichever you find easiest to write. So long as you find a reasonable algorithm, performance is unlikely to be a major issue until at least the 4th of 5th problem. I use Python for my submissions, and (using PyPy3 to run it) I have yet to find a problem that it is too slow for.

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

      Thanks a lot for giving your valuable advice...It's surly motivates me a lot..

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    2 weeks ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    • A-difficulty between 800 to 1200 with tags including 'brute force', 'implementation', 'math', 'sorting' (rarely), etc;
    • B-difficulty between 1200 to 1500 with tags including 'binary search', 'data structure', 'divide and conquer', 'strings', 'combinatorics', etc;
    • C-difficulty between 1400 to 1800 with tags including 'dp', 'dfs', 'trees', 'graphs', 'bitmasking', etc;

    Moreover, after the contest is over you can always read the editorials or can refer others solutions. You can practice for any difficulty or any tag from the problemset by using filter provided on the right side.

    "Happy Coding :)".

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

      Thanks a lot...... I will remember your suggestions... again thanks a lot .... "Happy Coding you too & this community :)"

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3 weeks ago, # |
  Vote: I like it +56 Vote: I do not like it

As a Tester I feel that the problem set is more diverse and good for everyone , there is something for everyone to solve and ya the round is good for those who just want to start with competitive coding!. Hope everyone to give this nice round!

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

Any specific reason for the unusual time?

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

Very Excited for your first contest!!

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3 weeks ago, # |
← Rev. 2   Vote: I like it +85 Vote: I do not like it

I think that's the beauty of codeforces. We get the best of problems from different countries which covers lot of diverse types of problems and helps us improve in different areas with each contest. We got 2-3 good indian rounds, this one is an Iranian round and 654 Div2 will be a Japanese round:).

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    2 weeks ago, # ^ |
      Vote: I like it +25 Vote: I do not like it

    First time when i came across this platform, I found it very weird because it's UI is not very attractive but when i started participating in contests I have just fallen in love with this platform and no other coding platform gives me this much of joy while solving questions. I think codeforces community is really great and helps a lot in growing as a competitive coder.

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3 weeks ago, # |
← Rev. 6   Vote: I like it -106 Vote: I do not like it

Now Wish you Bad luck for downvoting bruh!

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3 weeks ago, # |
  Vote: I like it -84 Vote: I do not like it

Downvoted. There's no reason to drag in religion here on Codeforces -- keep it to yourself.

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    2 weeks ago, # ^ |
    ← Rev. 2   Vote: I like it +283 Vote: I do not like it

    I don't see any reason to not to add a single line, which doesn't hurt anyone in any kind(or does it?). If i could see, then i would not.

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      2 weeks ago, # ^ |
        Vote: I like it +170 Vote: I do not like it

      I'd say the setter has some freedom to include selected topics in his announcement/problems. A few contests back we defended Codeforces Round #645 (Div. 2) for having the corona-virus theme. Clearly, while the theme is offensive to some people, the vast majority of users seemed to find no harm in the in the author expressing his personal humor here.

      We must not adopt double standards: we tend to give our authors leeway to include their personal touch in their contests and announcements. Whether it is references to anime, marvel universes, corona, or religion, a persona touch is usually tolerated by the community historically.

      If a subject is considered too divisive then the community will naturally express it with sufficient downvotes, so either way we'll find out what everyone thinks.

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        2 weeks ago, # ^ |
          Vote: I like it +24 Vote: I do not like it

        I think allowing the authors to add their 'personal touch' is the right approach. It's lots of work to author a contest, they should be able to broadcast their messages to people who read the CF announcements.

        Also, I can't imagine too many people caring enough to mass downvote an announcement or editorial. And this is good because most of us are here to improve on our CP abilities and not to get offended by the authors' political views, religion, and memes.

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          2 weeks ago, # ^ |
            Vote: I like it -9 Vote: I do not like it

          I think as long it is not offensive for anybody, authors can add whatever they want.

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      2 weeks ago, # ^ |
        Vote: I like it +43 Vote: I do not like it

      You can proudly add it bro. I think, this will not hurt anyone.

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      2 weeks ago, # ^ |
        Vote: I like it +23 Vote: I do not like it

      I personally love when the authors include their personal touch to problems(or blog) and the editorials. It feels real-like problems. Also if you make an editorial like this I'd love it :-)

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

        Differences are the nature of this world and nobody is right to blame another cause of something that they don't have in common. You are absolutely right!

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    2 weeks ago, # ^ |
      Vote: I like it -94 Vote: I do not like it

    When You are not start every work with name of GOD means there are not any GOD that is the best.

    if he use "In the name of Allah" it may be correct but it's a General sentence and all of people know it and hear it at least once.

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      2 weeks ago, # ^ |
        Vote: I like it +134 Vote: I do not like it

      Reading it the 5th time. I don't understand what you are saying.

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    2 weeks ago, # ^ |
      Vote: I like it -50 Vote: I do not like it

    I agree with GreenGrape, bringing religion into a platform like Codeforces can only divide people.
    If it goes on, eventually it will definitely escalate. Maybe, next time someone will say characters in their round are of their religion and its their contest and it should be allowed. Also, not to mention many people do not believe in god or religion, to whom it definitely seems bad.

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    2 weeks ago, # ^ |
    ← Rev. 2   Vote: I like it -57 Vote: I do not like it

    FYI in Iran it's a formal compulsory custom, much like a head cover for girls. Every article, movie etc. must start with this string. It's not an author's personal statement. More like a national trademark for a text.

    please correct me if I was wrong.

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      2 weeks ago, # ^ |
      ← Rev. 2   Vote: I like it -24 Vote: I do not like it

      Yeah you're right! Just like a white-man in America that MUST be racist if not he should survive under Polices' hits. Just stop trying to make a saint out of yourself.

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

        [Deleted]

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

          No you didn't. And let me make things clear. The author has not followed any compulsories. Just personal beliefs.

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

      omg, why som many downvotes lol? If anyone bothers to explain, I'd gladly read that.

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

        So let me to do so. You just tried to make a bad and ugly face out of Iran with mentioning Iranian "formal compulsory" and pretending that they are just in Iran! And I think you got a proper feedback.

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

    Guys! Just take it easy! You are blaming the author cause of adding a simple line with some common words(And not a verse of Quran!), while you are sharing the black lives matter hashtag on Instagram and Twitter, HYPOCRITICALLY! You put knees on faiths' throat and try to kill them instead of learning that they exist, and you should live along them. I'm sorry if I just hurt someone with a kind of brute comment, but think about it!

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      2 weeks ago, # ^ |
      ← Rev. 4   Vote: I like it +6 Vote: I do not like it

      Bismillāh is not "some common words", and your metaphor is ridiculous. Regardless, everyone should be free to follow their beliefs and traditions.

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        2 weeks ago, # ^ |
        ← Rev. 2   Vote: I like it +1 Vote: I do not like it

        Do you see any "Allah" word?! God is a common word that doesn't really refer to any specific religion. It's not Allah, Jesus and things like that which they belong to a religion. Of course God is a common and general word

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

          "Allah" is just an Arabic word for "God", and the phrase is unmistakably recognizable.

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    2 weeks ago, # ^ |
    ← Rev. 2   Vote: I like it +6 Vote: I do not like it

    Stop being so boring

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

    Are you a militant atheist?

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2 weeks ago, # |
← Rev. 2   Vote: I like it +111 Vote: I do not like it

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2 weeks ago, # |
← Rev. 5   Vote: I like it +37 Vote: I do not like it

Ok, I'm deleting this meme.

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2 weeks ago, # |
  Vote: I like it +44 Vote: I do not like it

In the name of God... Me an atheist....

It is going to be an interesting round.

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    2 weeks ago, # ^ |
      Vote: I like it +196 Vote: I do not like it

    I promise that the problems are not affected by religions in any kind.

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

      I don't know why people are talking so much just for "In the name of God". The main motive should be to participate and learn as much as you can. I think pointing someone just like this is not good. And we as Codeforces Community are "ONE".
      I request MikeMirzayanov to make this clear to everyone, please.

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    2 weeks ago, # ^ |
    ← Rev. 3   Vote: I like it -28 Vote: I do not like it

    Deleted

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2 weeks ago, # |
← Rev. 2   Vote: I like it -6 Vote: I do not like it

Great

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2 weeks ago, # |
  Vote: I like it -41 Vote: I do not like it
  • Will this round be rated?
  • How many people will be participating?
  • Is there going to be any math involved?
  • How large are the statements?
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    2 weeks ago, # ^ |
      Vote: I like it +25 Vote: I do not like it
    1. Yes.
    2. God knows.
    3. No.
    4. Enough. GL & HF!
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    2 weeks ago, # ^ |
      Vote: I like it -16 Vote: I do not like it

    Please stop downvoting me. I was just asking a question.

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

      The round is rated for participants with rating strictly less than 2100

      Why do you even bother asking these questions?

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

    And then you complain about getting downvotes, asking such stupid questions that can be anwswered by reading the announcement

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

Looking forward to the contest!

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2 weeks ago, # |
  Vote: I like it +38 Vote: I do not like it

Lol Ashishgup everywhere orz...

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

[Deleted]

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    2 weeks ago, # ^ |
      Vote: I like it -19 Vote: I do not like it

    you can not be a good coder by skipping geometry problem.so need to practice more in which you are weak

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    2 weeks ago, # ^ |
      Vote: I like it -10 Vote: I do not like it

    Why not? One should be ready to deal with anything

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2 weeks ago, # |
  Vote: I like it -29 Vote: I do not like it

I wish there aren't any interactive problems because i'm done with those.

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2 weeks ago, # |
  Vote: I like it +29 Vote: I do not like it

Hey guys..did you notice vovuh is back with his div-3 round...? so excited!!

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

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2 weeks ago, # |
  Vote: I like it +115 Vote: I do not like it

Is it just me or do others feel as well that the quality of comments section is going down? All I see are a lot of shitty memes, "Is it rated" and relentless pursuit from a lot of people to just comment on something for the sake of it. It's extremely uncomfortable as quality discussion on problems gets suppressed due to a lot of this unnecessary crap

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2 weeks ago, # |
  Vote: I like it -26 Vote: I do not like it

So continuing this series ;)

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

The last time there was a single setter vs an army of testers,Ehab happened! Hope God saves this round!

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2 weeks ago, # |
  Vote: I like it +26 Vote: I do not like it

Please mention about unusual start time in announcement. I noticed it after reading it in comment section.

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

    What is Usual start time?

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      2 weeks ago, # ^ |
        Vote: I like it +35 Vote: I do not like it

      It is usually 14:35 UTC. I think you should include it in announcement as many presume the usual time.

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

        Thanks dude, I really didn't know it(no joke), blog is updated.

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2 weeks ago, # |
← Rev. 2   Vote: I like it +70 Vote: I do not like it

BTW I did my best to make the statements as short and clear as they should be, stories are written in another font so you can skip them, but don't forget to read them when waiting for system test. I tried to lessen number of tests so we should not see long queues.

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

    you lessened the number of tests !

    I wish that they are strong so no one solution will fail

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

    Congrats on your first round. You are among the most interactive and approachable problem setters in codeforces community. It's your excitement for the round which makes it special.

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

You welcome.

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

guys post god memes

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2 weeks ago, # |
  Vote: I like it -62 Vote: I do not like it

Take Love DeadlyCritic my muslim brother.This is for the first time i have seen "In the name of God(Allah)" in any announcement blog! May Allah help you for your good deeds.

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

thanks for your explanation!

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

    Polygon is the platform where all the problem is set, tested, and validated for the Codeforces round !!

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    2 weeks ago, # ^ |
      Vote: I like it -7 Vote: I do not like it

    Simply, Polygon is the manufacturer of Codeforces problems.

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

All the best to you for your maiden contest!

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2 weeks ago, # |
  Vote: I like it +23 Vote: I do not like it

Thank you for remembering me.

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2 weeks ago, # |
  Vote: I like it -22 Vote: I do not like it

How much money does someone makes by problem setting in these contests ,

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    2 weeks ago, # ^ |
      Vote: I like it +72 Vote: I do not like it

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      2 weeks ago, # ^ |
        Vote: I like it +53 Vote: I do not like it

      Coffee is expensive. :(

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

      How tf are such low quality irrelevant memes getting such upvotes? Not fair to those who work their asses off to make worse memes and still get more upvotes!

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

    Only sufficient for a Wifi or Data Recharge! for next contest!

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

      So you get a recharge for every contest?

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

        Sometimes When my limited netpack (1.5 GB/day ) for the whole day becomes empty then I do take a recharge.

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

          I generally use an opposite strategy, either i don't use net or use it very carefully till the contest XDXD

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

    Why the downvotes ? It's a genuine question...

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2 weeks ago, # |
← Rev. 2   Vote: I like it -32 Vote: I do not like it

once again Ashishgup

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

Edit: Got it. thanks.

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

.

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2 weeks ago, # |
← Rev. 2   Vote: I like it +91 Vote: I do not like it

Well ,Is there anybody else other than me who can relate to this ?
WhatsApp-Image-2020-06-22-at-4.00.51-PM.jpg

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2 weeks ago, # |
← Rev. 2   Vote: I like it +14 Vote: I do not like it

Score distributions are out.

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2 weeks ago, # |
← Rev. 2   Vote: I like it +11 Vote: I do not like it

Till now I was thinking that the round will be held today. I was prepared for it. :(

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2 weeks ago, # |
← Rev. 2   Vote: I like it -17 Vote: I do not like it

OK, got it.

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

I am waiting for this contest. Hope, it will be very interesting.

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    2 weeks ago, # ^ |
      Vote: I like it -13 Vote: I do not like it

    Everybody is hoping for interesting problems but not everybody is commenting "HOPE, IT WILL BE INTERESTING" So shut up

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2 weeks ago, # |
← Rev. 2   Vote: I like it +9 Vote: I do not like it

Hope your first contest will be more interesting.

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

I have a good feeling to this contest <3 ;)

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

How can i see my solved problem distribution on CF ? (difficulty-wise) Thanks in advance........

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2 weeks ago, # |
← Rev. 2   Vote: I like it -9 Vote: I do not like it

.

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

DeadlyCritic Bro what an inspiring curve of rating you have . As a beginner these things motivate me a lot . Hoping to have more rounds from you!!

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    2 weeks ago, # ^ |
      Vote: I like it +12 Vote: I do not like it

    To further motivate you, just check ruban 's graph. You will understand the dedication towards cp

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

      I thought my dedication level is pretty strong
      But after seeing this I realize, compared to him, mine is nothing!
      hats off ruban

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

UNUSUAL TIME

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2 weeks ago, # |
  Vote: I like it -69 Vote: I do not like it

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2 weeks ago, # |
  Vote: I like it -48 Vote: I do not like it

Atheist: Hoping for an interesting round !!

God : You'll have a difficult time in this contest :p

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2 weeks ago, # |
  Vote: I like it -10 Vote: I do not like it

Me: Yes, I can do it. I can solve all the problems. I will be rank 1. But after solving at max two problems, enough I am done with it. I am going to sleep.

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2 weeks ago, # |
  Vote: I like it -20 Vote: I do not like it

Hope to see problem from number theory

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

I hope to be a pupil in today's contest anyway.

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

CodeForces and all the problem setters, coordinators, testers are doing an amazing job to arrange such good contests on such regular basis. Hats Off to their efforts!

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2 weeks ago, # |
  Vote: I like it +29 Vote: I do not like it

Why people nowadays are discussing such irrelevant topics in the comment sections?You guys have other social sites to do these stuffs.CF is not the right place to share memes & have a discussion about if the author can add "In The Name of God" in his post or not.

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    2 weeks ago, # ^ |
      Vote: I like it -17 Vote: I do not like it

    Why so serious man? Discussion, if not unhealthy, should be welcome everywhere right?

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

    It's only natural that the discussion started in the comment section of the post where the phrase being discussed was used.

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

    I think it's really good to discuss respectfully about such stuff in a special community like coders and programmers of all around the world. Like what we two just did!

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2 weeks ago, # |
  Vote: I like it -12 Vote: I do not like it

Humble request to authors: Don't make it Propaganda forces Thank you!

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

    Expression of personal faith is not propaganda.

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

      Some people are keen on downvoting obvious facts. :)

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

    Come-on man! Just take it easy. Nobody can hold a propaganda by just a simple line with some really common and general words.

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

Hopefully, your entry as a contest writer will be interesting and hoping for an interesting contest as you said :).

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

https://codeforces.com/blog/himanshu_attri please someone help me with this problem it will be very helpful thank you in advance this is first time i am asking for help

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2 weeks ago, # |
  Vote: I like it +12 Vote: I do not like it

submissions in queue for a long time. will contest delay?

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2 weeks ago, # |
  Vote: I like it -19 Vote: I do not like it

This time is very unusual as per India. As many of the students stay in the hostel, and it coincides with dinner timings of the mess: 1930-2130 IST. So either we have to skip dinner or lag in the contest.

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

    its not tough to delay dinner about 1/2 hours..Its worldwide..so some people always face problem brother..

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

    dude leave this contest and go to your home first, :)

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

    I don't know if you are lucky to have nice food in mess, I never gave a thought to skipping or lagging in contests for mess food.

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

    U are in college at the time of this lockdown ? Seems very far-fetched :P

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

Why it is written codeforces and polygon platform, and what is the meaning of polygon platform?

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

GLHF EVERYONE!

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

i registered but i cant submit my code..

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

I forgot to register can't I participate now?

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

this is so annoying, i have written my code but cant submit it , why should i be penalized for this round if i have already written code and registered..

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

...

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

I have registered but cannot submit my code.

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

    I see no reason why that should happen. Have you registered for the contest ?

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      13 days ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      i was able to submit the code after 10-12 mins after the start of the contest.

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

Man I keep getting Wa on A again I solved 3 problems and my rating will stay the same :(

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

    At first I thought, at least one edge should be parallel! :(

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

      You need to start working on your reading comprehension. :)

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2 weeks ago, # |
  Vote: I like it +30 Vote: I do not like it

How to solve D What was D.

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    2 weeks ago, # ^ |
    ← Rev. 3   Vote: I like it +10 Vote: I do not like it 
    if(x%3==0) f(x) = 2*f(x-2) + f(x-1) + 4
else f(x) = 2*f(x-2) + f(x-1)
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      2 weeks ago, # ^ |
        Vote: I like it +7 Vote: I do not like it

      can you please prove this.i was able to get both recurrence but was not able to figure out when to put the condition .

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

        The tree of level x can be decomposed into three subtrees of level (x-2), (x-2), (x-1) respectively, which are connected by root node. Claws can be chosen from the bottom. The claw including root is used for x=3. For x=4, one subtree will be of level 3 so its root cannot be used. For x=5, two subtrees will be of level 3 so root cannot be used. For x=6, the roots of all three subtrees are unused so one more claw can be picked. similarly, for every multiple of 3 one extra claw is picked.

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2 weeks ago, # |
← Rev. 2   Vote: I like it +22 Vote: I do not like it

I lost too much time convincing myself that the proof for problem B I had in my mind was correct :D Anyway, I really enjoyed the problems. It was a good contest.

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2 weeks ago, # |
  Vote: I like it +20 Vote: I do not like it

"For each test case, print a single integer — the maximum number of yellow vertices Lee can make modulo 10^9+7." — having the maximum modulo instead of the maximum actual answer modulo 10^9+7 was very nasty. Should have been explained better, as usually the problems require the actual maximum modulo something.

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

    What? I think that's just messed up wording, because I solved the standard problem and passed the pretests.

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2 weeks ago, # |
← Rev. 2   Vote: I like it -8 Vote: I do not like it

Summary of the contest:

Wrong answer on pretest 2

Easy D

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    2 weeks ago, # ^ |
    ← Rev. 3   Vote: I like it +36 Vote: I do not like it

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      2 weeks ago, # ^ |
        Vote: I like it +35 Vote: I do not like it

      Stop making so big pictures... You can easily resize it.

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

        Sorry, this is the first time I've ever posted a meme. It looked way too big for me as well. Does codeforces has a resize tool built-in?

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

          No, you can save lower resolution in Paint, for example. Now it's nice :)

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

How to solve D??

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

    $$$f(n) = f(n-3) + 4*T_{n-2,0}$$$
    where $$$T_{n,0}$$$ is the number of nodes with degree 0 in the RDB of level n

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

Please don't write −In the name of God − from next time :(

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    2 weeks ago, # ^ |
      Vote: I like it +25 Vote: I do not like it

    Please don't comment Please don't write −In the name of God − from next time :( from next time :)

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

Waiting for editorial

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

How to solve problem E? I tried to model the problem using graph network- food type as node and each friend as edge. How to proceed?

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

    If solution exists then for any subset of people solution exists as well, so try to find a guy who can be in last position.

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

    E should be solved using greedy and has no relationship with graphs.

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

any hint for problem D !?

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

    Greedy from the bottom

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

    The tree obtained at level I is a combination trees obtained in level I-1 and level I-2. this is. A hint. Now everything is a Dp

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

    Think about how many leaves you can have in a k-level tree. You can build up your solution based on this.

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

    is it solvable by math solution ?

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

      All 1-D DP relations are actually mathematical functions. Same about this one. But obviously, here you would be needing memorization to avoid TLE.

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

    Use greedy and simple dp. The code is quite clean.

    for(int i = 5; i <= 2000000; i++){
	f[i] = (f[i] + 2 * f[i - 2] + f[i - 1]) % mod;
	if(i % 3 == 0) f[i] += 4;
}
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2 weeks ago, # |
  Vote: I like it +6 Vote: I do not like it

How to solve E? It is a variation of Cow and Snacks. How to handle multiplicity of plates?

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2 weeks ago, # |
  Vote: I like it +20 Vote: I do not like it

Nice and hard problem E, thank you author

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

I did not like this one. For me D and E where hard to understand, I restarted two or three times just to notice after some times that I did get the question wrong.

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

    Agree. I have to read D and E many times to understand them correctly. The statements are easy to cause confusion.

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

You tried to make a hard D ? You definitely made a deceptive D. Loved solving it.

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

    Actually earlier D was something Different which you might not Like , this was invented after hardships , this was a really nice DP problem I ever solved.

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

Video Tutorial B:https://www.youtube.com/watch?v=GhR1nXq6Y7Y

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2 weeks ago, # |
← Rev. 4   Vote: I like it +48 Vote: I do not like it

I don't know why my D solution is correct.

    for (int i = 4; i <= 2000000; i++)
        f[i][0] = max(f[i - 1][0], f[i - 1][1]) + max(f[i - 2][0], f[i - 2][1]) * 2,
        f[i][0] %= P,
        f[i][1] = 4 + f[i - 1][0] + 2 * f[i - 2][0],
        f[i][1] %= P;
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    2 weeks ago, # ^ |
    ← Rev. 2   Vote: I like it 0 Vote: I do not like it

    Edit: oh nvm disregard

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    2 weeks ago, # ^ |
    ← Rev. 2   Vote: I like it -10 Vote: I do not like it

    [deleted]

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    2 weeks ago, # ^ |
      Vote: I like it +12 Vote: I do not like it

    You are very lucky, because the modulo of the max is different from the maximum of modulo. But in this problem the two values doesn't differ from more than 4, so with some luck it works.

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

    you get maximum of two thing that differ at most one. this solotion is correct but our solotin is another thing

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

    Generally max(a, b) != max(a % mod, b % mod)

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

      Wow, it's true, and my solution with max should fall, but it worked :)

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

        It should not, as we know $$$a$$$ and $$$b$$$ differ by $$$4$$$ at most, so it works as long as $$$max(a \% mod, b \% mod) < mod-4$$$, and smallest such $$$n$$$ was so big.

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

          Did you consider changing Mod value instead of N or was it intended to leave that solution AC?

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

            I didn't realize that I can change Mod, thanks I will note it for my later rounds, thank you. I prefer those solutions to fall, at least one-third of the solutions would fall.

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

              You're welcome :) I liked the problems actually they were very interesting. In the contest I've written solution similar to his one but was sure it will fail and you planed to trick us with such a case so I gave it 10 minutes more to find out the pattern when N is divisible by 3! That's why I tried to generate a valid MOD to prove I was thinking correctly LOL.

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

                :), If the MOD was something special, then yes I would do the same, but not when MOD is $$$10^9+7$$$. Also the sample had $$$2\cdot 10^6$$$, so there were no room for WA. Except some special Time Limit exceeded.

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

                  Sure actually $$$1000002193$$$ is the first prime number >= $$$10^9$$$ which could make their solution fail as I tested for each prime all possible values of N. I know it's hard to find such cases unless you predict that someone would do that exact solution while writing the problem constraints!

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

    I think it's OK, this is my code:

    for(i=3;i<maxn;i++){
	f[i][0]=(max(f[i-2][0],f[i-2][1])*2+max(f[i-1][0],f[i-1][1]))%mod;
	f[i][1]=(f[i-2][0]*2+f[i-1][0]+4)%mod;
}

    Isn't it right? Why you think it's incorrect?

    My English is't well, please forgive me. ovo

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

      2*(1e9+7) < maxint

      So that it works well

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

      you're comparing 2 numbers that are in module 1e+9 +7, but i dont know why it's AC

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    2 weeks ago, # ^ |
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    To be sure that they will be no errors with the max, you can remark that the second value is greater than the first one if and only if i%3 == 0

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2 weeks ago, # |
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Very descriptive questions. And I must say, the names were quite good too.

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2 weeks ago, # |
← Rev. 2   Vote: I like it +23 Vote: I do not like it

Why problem D I can mod then max to pp the testcases?

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    2 weeks ago, # ^ |
    ← Rev. 2   Vote: I like it +11 Vote: I do not like it

    No need to use max, ans is:

    dp[x] = (4*(!(x%3)) + ((2LL*solve(x-2))%mod + solve(x-1))%mod)%mod;

    PS: Just clarifying that badcw was asking another thing before, I have no idea why the solution with max works.

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      2 weeks ago, # ^ |
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      Thanks, I check it's all correct in [1,2e6]

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2 weeks ago, # |
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Can someone please help me out with B?

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    2 weeks ago, # ^ |
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    you just have to find first and last occurrence of "1" and change substring between first and last "1" to either "0" if any "0" is present in it . or substring remains same if there is no "0" in it

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    2 weeks ago, # ^ |
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    (1.......0) : this will always get converted to 0 no matter what is between them.

    So,look for the first occurrence of "1" from beginning,lets say that index is x and first occurrence of "0" from last,that index is y.

    if(x<y) : Print the string except the part from index x to index y and replace that part with "0". else : Print the string as it is.

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