Arpa's blog

Codeforces Round #383
By Arpa, history, 8 years ago, In English

Hi!

I'm honored to invite you to Codeforces Round #383, it will be held on 6nd December 14:35 UTC. There will be 5 problems for each division as usual. The contest was prepared by AmirReza Arpa PoorAkhavan and Mehrdad Batman Saberi. It's our first official contest at CodeForces.

The contest stories will be about Arpa and Mehrdad and some events happen with them in Arpa's land, in addition you will get some information about Arpa's land and girls living there (Owf (t = 1)).

I'd like to thank myself (:P) and Mehrdad at first, then Nikolay KAN Kalinin for helping me in preparing problems and Mike MikeMirzayanov Mirzayanov for the great Codeforces and Polygon platforms.

The scoring distribution will be announced later.

Answer for one of your common questions : -Yes, It is rated.

UPD. GL & HF. Hope you came up with Dokhtar-kosh solutions for our Dokhtar-kosh problems.

Urgent information from MikeMirzayanov: due to hardware issues, the round is moved to Tuesday 6th December, 14:35 UTC. We are very sorry this happened. More information is available in this post.

UPD. Scoring distribution: Div.1 : 500-1000-1250-2000-2500, Div.2 : 500-1000-1500-2000-2250.

UPD. Contest is over, hope you have been Joon-Joon of the round :P

Congratulations to winners:

Div.1:

1 . jqdai0815

2 . mnbvmar

3 . data_h and nuip (WoW :O)

5 . Phronesis

Sepcial congratulations to anta who solved Div.1 E.

Div.2:

1 . gilcu3

2 . toHisDream

3 . Far

4 . shpsi

5 . orz_liuwei

Editorial is ready.

  • Vote: I like it
  • +459
  • Vote: I do not like it

Comments Comments (366)
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8 years ago, # |
  Vote: I like it +4 Vote: I do not like it

Hope for finally become orange :)

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    8 years ago, # ^ |
      Vote: I like it +20 Vote: I do not like it

    Its Arpa, not ADJA.

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

      Well, there are some cool coincidences, like:

      1. They are both candidate master
      2. They are both are first-time Codeforces round writers
      3. They are both have handle start and end with "A", and four letters

      So, I hope increase of rating will also become coincidence :P

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        8 years ago, # ^ |
          Vote: I like it +133 Vote: I do not like it

        Mother of logic.

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          8 years ago, # ^ |
            Vote: I like it +35 Vote: I do not like it

          We need a bit more positiveness these days :)

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            8 years ago, # ^ |
              Vote: I like it -121 Vote: I do not like it

            I share a secret with you, don't tell to anyone: You can buy problems by just $100, tell me if you want them.

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              8 years ago, # ^ |
                Vote: I like it +24 Vote: I do not like it

              Lol!!! I bet you want to sell them after the contest, right? :'D :P

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                8 years ago, # ^ |
                  Vote: I like it +17 Vote: I do not like it

                DP? Again DP problems? ( Oh, I see it everywhere

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                  8 years ago, # ^ |
                    Vote: I like it +4 Vote: I do not like it

                  @bekar13 :D why he need to wait for the end of the contest? he can sell it when the contest starts ;)

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

                  Mr.Adnan don't you think that he will be busy in that time for judging and giving clarifications? ;)

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    8 years ago, # ^ |
      Vote: I like it +12 Vote: I do not like it

    if you want, you can!

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    8 years ago, # ^ |
      Vote: I like it +61 Vote: I do not like it

    2191 :|

    I'm starting to think maybe my rating is asymptotic to 2200.

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      8 years ago, # ^ |
      ← Rev. 4   Vote: I like it +4 Vote: I do not like it

      You havn't face the real asymptotic,bro. I'm starting to think maybe my rating is asymptotic to 1820

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        8 years ago, # ^ |
          Vote: I like it +28 Vote: I do not like it

        And my graph does not have a limit, because it's a function of type f(n) = ( - 1)n ;)

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8 years ago, # |
  Vote: I like it +44 Vote: I do not like it

what does that (t=1) mean???

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    8 years ago, # ^ |
      Vote: I like it +4 Vote: I do not like it

    Please wait just for 48 hours. You will understand the meaning in Div1.A.

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    8 years ago, # ^ |
      Vote: I like it +38 Vote: I do not like it

    I don't know too :/

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    8 years ago, # ^ |
      Vote: I like it -16 Vote: I do not like it

    Maybe he means owtf(oh what the father) If you mean this arpa, i have to tell you that it is so funny haha :|

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      8 years ago, # ^ |
      ← Rev. 2   Vote: I like it +7 Vote: I do not like it

      if you think you are very funny you can create your own contest.
      dont spam in this blog

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8 years ago, # |
  Vote: I like it -27 Vote: I do not like it

Hope the english translation is better than this blog !

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    8 years ago, # ^ |
      Vote: I like it +10 Vote: I do not like it

    I wouldn't hold out my breath though :D

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8 years ago, # |
  Vote: I like it +11 Vote: I do not like it

Hope this time I won't fall back to div2 immediately :D

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8 years ago, # |
  Vote: I like it -14 Vote: I do not like it

the new question should be: will the problemset contain googable problems??? is it rated became too old :D

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8 years ago, # |
  Vote: I like it +37 Vote: I do not like it

Hope to become green again guys pray for me!!

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8 years ago, # |
  Vote: I like it -210 Vote: I do not like it

Since, no one asked this above and there is no seriously hated down-voted to hell comment above, I would like to ask this: Is it rated?

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    8 years ago, # ^ |
      Vote: I like it +27 Vote: I do not like it

    Read post again carefully.

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    8 years ago, # ^ |
      Vote: I like it +17 Vote: I do not like it

    Here you are :P -76 just in 13 hours. GoodLuck and high contribution :P

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

number 383 is prime && palindrome! ：）

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

I've been waiting for along time to see how Batman can do in problem setting
I'm very exciting , hope you guys won't disappoint us

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

    Thanks a lot...

    We tried our best for the contest... But by the way, I don't guarantee anything at all :)...

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

I like the characters of Arpa and Mehrdad
who did paint them or they have copied from the Internet ?

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    8 years ago, # ^ |
      Vote: I like it +16 Vote: I do not like it

    I painted them...

    And there are other paintings in the problem statements too... Hope you enjoy them :)

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8 years ago, # |
  Vote: I like it +25 Vote: I do not like it

The Codeforces is begging me to "Register Now" and also asks me to pay attention...

Try to control your site admins... It has some devil plans...

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

Glad to see our Codeforces is back! Thanks to the maintainers' hard efforts.

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    8 years ago, # ^ |
      Vote: I like it +27 Vote: I do not like it

    I got a mini heart attack when it read :

    Temporarily, because of hardware issues Codeforces and Polygon are not available. We hope to fix it before January, 11, 11:00 MSK. We apologize for the inconvenience.

    What would I had done for 1 month :3

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

your graph is really inspiring Arpa ! :)

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

    Thanks, I need to write about my story as some people wanted from me (link), but I haven't enough time, sorry :(

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      8 years ago, # ^ |
        Vote: I like it +6 Vote: I do not like it

      Your submissions are enough to tell your story :)

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        8 years ago, # ^ |
          Vote: I like it +13 Vote: I do not like it

        If you mean "number of submissions" by "submissions", I'd like to post my graph here :

        If you mean "special comments on top of the code" by "submissions", Some of them can tell something to you. But last one : "Someone like you"?! Unbelievable ... refers to my love and it is totally unrelated.

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

          How'd you get that graph?

          Are there any other such graphs?

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          8 years ago, # ^ |
            Vote: I like it 0 Vote: I do not like it

          Tell me... Whose your love Arpa? :D

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

            Why you are asking while you know him as well as I know?! In addition you will know him better in Div.1 E.

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Isn't it weird that you didn't want to thank GlebsHP?

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    8 years ago, # ^ |
      Vote: I like it +23 Vote: I do not like it

    He wasn't involved in preparation, KAN helped me instead.

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      8 years ago, # ^ |
        Vote: I like it +36 Vote: I do not like it

      That's true. Moreover, there were already some rounds recently that were prepared without my help.

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

i wish you will make a good contest brother Arpa .good luck for all.

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

it's my birthday guys.:) i get my rate up .

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8 years ago, # |
  Vote: I like it -27 Vote: I do not like it

As you gave thanks to yourself, you needed to thank us (contestants ) also :/

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    8 years ago, # ^ |
      Vote: I like it +26 Vote: I do not like it

    Users are showing their thank with minuses.

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8 years ago, # |
  Vote: I like it +12 Vote: I do not like it

is it usual ?

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8 years ago, # |
  Vote: I like it -100 Vote: I do not like it

God with us, brother.

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    8 years ago, # ^ |
      Vote: I like it -34 Vote: I do not like it

    fck u stupid extremist.

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      8 years ago, # ^ |
        Vote: I like it +34 Vote: I do not like it

      Please be polite. Everyone has some beliefs. "All we are brothers", is slogan of Islam.

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        8 years ago, # ^ |
          Vote: I like it -9 Vote: I do not like it

        wtf he posts a terrorist's photo

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          8 years ago, # ^ |
          ← Rev. 2   Vote: I like it +10 Vote: I do not like it

          Oh ! Maybe you are right, but it isn't enough reason to misbehave.

          UPD I think he wants to misrepresent Islam.

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        8 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        Only Muslims(not all) are brothers according to your Islam, and others are terrible sinner who are going to be punished by Allah, isn't it what your Islam says?

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          8 years ago, # ^ |
            Vote: I like it +10 Vote: I do not like it

          You can post sources.

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            8 years ago, # ^ |
            ← Rev. 3   Vote: I like it -16 Vote: I do not like it

            Listen, I'm not Muslim, so don't ask me for proof. I've talked with many Muslims and all of them has agreed with that. So they suggested me to take Islam and Allah would forgive me.

            And if you want proof whether Allah has indeed said it or not, ask Mohammad (the Islam prophet). If you can't do that then just die and meet him directly.

            ps: don't mind if you didn't mean to ask for a source, I can't understand whether you asked me or told me to do something.

            UPD: Source added below.

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

              ps: don't mind if you didn't mean to ask for a source, I can't understand whether you asked me or told me to do something.

              I stated something that's good practice when making an argument for or against... well, anything.

              You can research it yourself (Quran and some texts around it); a lot of people have. I'm intentionally being vague in order to not hint at what you'll find (and to have fun).

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                8 years ago, # ^ |
                  Vote: I like it +6 Vote: I do not like it

                "As to those who reject faith, I will punish them with terrible agony in this world and in the Hereafter, nor will they have anyone to help."
                source: https://goo.gl/46zNQB

                "We have special responsibilities towards our brothers and sisters in Islam that we do not have towards the non-Muslim"
                source: https://goo.gl/NXl7xB

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

            And now I remember, my friend once told me that at his last speech Mohammad said that all Muslims are brothers. (though He also told not to enforce other races to take Islam). So I think you can take Mohammad as the "source".

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8 years ago, # |
  Vote: I like it +32 Vote: I do not like it

What is this "In the name of God" thing?

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    8 years ago, # ^ |
      Vote: I like it +48 Vote: I do not like it

    "Anything which doesn't starts with "In the name of God" is incomplete"

    -- Mohammad (the Islam prophet).

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      8 years ago, # ^ |
        Vote: I like it +30 Vote: I do not like it

      Allahu Ekber brother.

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        8 years ago, # ^ |
        ← Rev. 2   Vote: I like it +27 Vote: I do not like it

        This is the most common phrase to utter before a Muslim die or kill "in the name of God". I hope you are still safe, dear!

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      8 years ago, # ^ |
        Vote: I like it +108 Vote: I do not like it

      This comment is incomplete

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8 years ago, # |
  Vote: I like it -12 Vote: I do not like it

I hope I get to feel the colour cyan. Just 6 points away from it.

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    8 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Then you have to solve at least 3 problems probably.

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

      Solving A and B fast should be enough (10 minutes for A and 20 minutes for B).

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8 years ago, # |
  Vote: I like it -16 Vote: I do not like it

Are problems on russian?

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

hope for becoming blue finally

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

After 7 months, I am back. :)

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    8 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    to steal some points .. huh ???

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      8 years ago, # ^ |
        Vote: I like it -13 Vote: I do not like it

      You stole the whole round, right? !! And moved it to 6,December. :D

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

    You're here also!? :D just because of you the contest rescheduled! @RippleOfLove

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      8 years ago, # ^ |
        Vote: I like it -13 Vote: I do not like it

      The CodeForces is not only for you, right? !!

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        8 years ago, # ^ |
          Vote: I like it -16 Vote: I do not like it

        Yeah right! you wasn't there, everything was fine! Just you came and see what's going on ! :/

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          8 years ago, # ^ |
            Vote: I like it -10 Vote: I do not like it

          who is he? why do you think like that?

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            8 years ago, # ^ |
              Vote: I like it 0 Vote: I do not like it

            He is a cheater! :D stole money from 100+ programmers to arrange a contest, but he couldn't manage the contest. Now he isn't returning money to all :D Do I need any other reason or am I behaving worst to him? :P +nandrewjh

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8 years ago, # |
  Vote: I like it +1 Vote: I do not like it

Come back Codeforces after nearly 2 years. Wish me good luck!

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8 years ago, # |
  Vote: I like it +16 Vote: I do not like it

And, I'd like to thank myself (:P) for reading Arpa's Blog :D

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

how to make codeforces in English again it became in russian ?

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

hope the contest be cool as the painting. (but i guess mehrdad's eyes(in the painting) are saying it's gonna be hard enough! :D)

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

    Yeah, he looks a little bit scary. On the other hand Arpa looks so innocent :P Maybe the painting has some hidden message about the problem set too(easy problem with so many corner cases) ;)

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

      i think Arpa looks like the main character of "The Little Prince" book in this painting and Mehrdad looks like a malefic person!(sure he isn't in real) :D (or maybe i'm just over judging a painting -_-)

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      8 years ago, # ^ |
        Vote: I like it +18 Vote: I do not like it

      We've found the father of logic too.

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

yayyy, another Persian contest. Hope to see funny problem statements like PrinceOfPersia's problem statements :D

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    8 years ago, # ^ |
      Vote: I like it +9 Vote: I do not like it

    you can not find it everywhere easily :)

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      8 years ago, # ^ |
        Vote: I like it +4 Vote: I do not like it

      I have some here... Come tonight and I'll show you...

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        8 years ago, # ^ |
        ← Rev. 3   Vote: I like it -19 Vote: I do not like it

        :|

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          8 years ago, # ^ |
            Vote: I like it -13 Vote: I do not like it

          First, be polite. In addition, don't challenge Batman, he is so dangerous. Wait and see his great works in problem statements :P

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          8 years ago, # ^ |
            Vote: I like it +6 Vote: I do not like it

          Such a dreamer...

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        8 years ago, # ^ |
          Vote: I like it +1 Vote: I do not like it

        Contest will moved to another date, lets take a virtual contest with our team, "Keyvan KL" tonight, then keyvankhademi will became happy ^_^.

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

          khademi moalem helli 1 e.

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

            It seems that I need to take another virtual contest with amsen with our team, "BK".

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              8 years ago, # ^ |
              ← Rev. 5   Vote: I like it +7 Vote: I do not like it

              It seems that I have to choose my team's name carefully :/

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            8 years ago, # ^ |
              Vote: I like it -7 Vote: I do not like it

            Mage energy hanuz madresas? :/

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              8 years ago, # ^ |
              ← Rev. 2   Vote: I like it -13 Vote: I do not like it

              felan ke sal pish 3 ta tala dad :/ Mahdi_Jfri

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                8 years ago, # ^ |
                  Vote: I like it -20 Vote: I do not like it

                Tabrik migm shoma mitunid bad tarin nasle energy bashid (0 specialist hatta!)

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

                  go and play with your toys

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                  8 years ago, # ^ |
                    Vote: I like it -14 Vote: I do not like it

                  sepanta Now i can see who has to go and play with his toys :)

                  couldn't even solve problem B? :)

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                  8 years ago, # ^ |
                    Vote: I like it 0 Vote: I do not like it

                  guys! please respect to others

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              8 years ago, # ^ |
                Vote: I like it +1 Vote: I do not like it

              they pressed down vote, because they do not understand the iranian language. write in this website Russian or English.

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

    :-)

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

I hope you guys will be the same active in comments after the contest. People usually need you so much right after contest ends...

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

    I will decide for it after the contest by considering the situation :)...

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

      Just make it cool and then accept compliments :)

      P.S. a tip: prepare the editorial before you get annoyed by comments "where is editorial"

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        8 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        But it's not just about the editorial, there should be lots of things I guess... So it's preferred to don't think about all of these, just saying something like good luck and have fun before the contest should be enough :)...

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        8 years ago, # ^ |
          Vote: I like it +7 Vote: I do not like it

        The editorial is already prepared by me, don't worry ; )

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8 years ago, # |
  Vote: I like it -13 Vote: I do not like it

Just curious. In the name of which god do you write?

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    8 years ago, # ^ |
      Vote: I like it -41 Vote: I do not like it

    There is only one God.The most fundamental teaching of Islam is to believe in the Oneness of God, in the sense of His being the only Creator, Preserver, Nourisher, etc. But this belief is not enough. Many of the idolaters knew and believed that only the Supreme God could do all this and yet they associated other gods with Him. Therefore, one must acknowledge the fact that it is God alone who deserves to be worshipped, and thus abstain from worshipping any other thing or being. Likewise, Muslims believe that God has no father or mother, no son or daughter. None is equal to Him. He is God of all humankind, not of a special tribe or race.

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      8 years ago, # ^ |
        Vote: I like it +31 Vote: I do not like it

      Thank you, man. You make me so glad of having been born in the west.

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

        good luck

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          8 years ago, # ^ |
          ← Rev. 2   Vote: I like it +13 Vote: I do not like it

          EDIT: The guy I replied to edited his post...

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            8 years ago, # ^ |
            ← Rev. 3   Vote: I like it -16 Vote: I do not like it

            . concentrate on contest

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              8 years ago, # ^ |
                Vote: I like it +31 Vote: I do not like it

              I assume you're an intelligent human being. You don't need dogmas, you are SMART, you have the possibility to be free, but instead choose to live imprisoned in ancient beliefs.

              If you had been born in India, you would believe in something else. If you had been born in Greece 3 thousands years ago you'd believe something different.

              I deeply believe every human being has the capacity to think for himself, don't waste this!

              Through history, humans have invented multiple religions, and there are tons of them RIGHT NOW. There's absolutely no reason to believe one is more real than the other.

              I'm very sorry you were born in such a harsh environment, with such strict views of the world, but I'm sure light will be shed on you eventually.

              Have a good day!

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                8 years ago, # ^ |
                  Vote: I like it +10 Vote: I do not like it

                sgioia tnx. but what you mean "dogmas"?

                you mean " Religion " ?

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

                  Not at all. Not all religions enforce dogma.

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                8 years ago, # ^ |
                  Vote: I like it 0 Vote: I do not like it

                this is your opinion .i don't have to consider it . and there is no need to prove that there is a god . just read more and ask some one who has a mind . ^_^

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                  8 years ago, # ^ |
                    Vote: I like it 0 Vote: I do not like it

                  Yeah, no problem. I'm sure you're comfortable getting your beliefs shoved up your butt =)

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            8 years ago, # ^ |
              Vote: I like it -20 Vote: I do not like it

            i wonder if your mother really knows who is your father .

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      8 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      Are you Sunni or Shi'i?

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      8 years ago, # ^ |
        Vote: I like it +72 Vote: I do not like it

      Thank God I live in a country where I'm not forced to believe in Him.

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        8 years ago, # ^ |
          Vote: I like it +15 Vote: I do not like it

        Thank Putin I live in a country where I'm forced to not be forced to believe in God.

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    8 years ago, # ^ |
      Vote: I like it +9 Vote: I do not like it

    Reply to above comments : Here is Codeforces, please move your discussions to another place.

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      8 years ago, # ^ |
        Vote: I like it +51 Vote: I do not like it

      These comments are relevant according to your blog. If you didn't write that irrelevant sentence at the start people would not ask for explanations. This is Codeforces, not an advertising site of spreading what you believe.

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        8 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        But it's fine I think...

        It's cool to read about different believes from different regions :D ...At least for me...

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          8 years ago, # ^ |
            Vote: I like it +7 Vote: I do not like it

          Cool for me too! As it is a community we can expect other's views and beliefs on different subjects, that's why Codeforces get festive mode in religious occasions. But, Author himself can not take these discussions easily, also some people here are crying as their feeling is getting hurt. And some would declare war for hurting their feelings.

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

        believe is a personal matter for everyone i think

        also i don't think that it can not be a annoying issue to all and specially you :P

        any way never mind :)

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          8 years ago, # ^ |
            Vote: I like it +10 Vote: I do not like it

          I believe you are dumb ass. because

          click here

          did you get hurt? see? sometimes it is not that simple. Totally irrelevant but just showed you an example how it can be more than personal.

          And no, It is annoying, read above comments. Some mis-beliefs can lead you to hate others. In worst case I think there will be a war soon.

          finally I didn't mind but sorry if author did.

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

        After a long delay (4 weeks), I'm here to say : It was my mistake, I want Codeforces community to excuse me.

        That sentence (In the name of God) was, and currently is, one of my beliefs, but now I know that I shouldn't write my religious beliefs in Codeforces.

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8 years ago, # |
  Vote: I like it +14 Vote: I do not like it

I have a question... what does the word "dokhtar kosh" mean?!

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    8 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    You will know it's meaning in Div.1 D.

    I'm interested in why you ask questions that are related to problem statements, You've asked three questions and all of them was related to some problem. It's so abnormal ...

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    8 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    It's a spoiler I guess.

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      8 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      No, it has meaning in persian.

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

    "dokhtar-kosh" meaning girl-friendly in persian language :)

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

It will be my first contest. Hope for a good start :)

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

Trust in Codeforces — there are so much lags and troubles with logging in and refreshing pages today.

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

I just want to know the meaning of "t=1", don't care if I lose some rating xD

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8 years ago, # |
← Rev. 2   Vote: I like it +57 Vote: I do not like it

Raise your hand if you think the contest will be delayed, postponed or at least won't run smoothly :/

Even if the problems turn out to be very good, it's not a good day for contest given the state of the servers. I feel bad for the writers :(

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8 years ago, # |
  Vote: I like it -14 Vote: I do not like it

383 is a prime number :)

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8 years ago, # |
  Vote: I like it +33 Vote: I do not like it

Glad to see that my student is becoming the master, good luck Arpa ;)

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

    Thanks PrinceOfPersia. I'm more glad to say you was (and currently are) my teacher. Wish the bests for you too.

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

      I could not participate in any prince_of_persia contests, hope to taste similarly nice problem set from you :)

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    8 years ago, # ^ |
      Vote: I like it +10 Vote: I do not like it

    How to become your student? Is there any way? =)

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

Urgent information from MikeMirzayanov : due to hardware issues, the round will be moved. what it means by "MOVED"?

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    8 years ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    why not tomorrow? what if after 4 days same problem exists? DO IT AFTER ONLY 3-5 HOURS NOT 4 DAYS

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      8 years ago, # ^ |
        Vote: I like it +1 Vote: I do not like it

      Read the post, they are going to NEERC which is held this weekend

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

      Because NEERC is to be held on December 3-4 — tomorrow and the day after tomorrow — so a lot of participants won't be able to write it

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Should we participate in the round ? The site is so buggy .

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Let me register on div2!

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8 years ago, # |
  Vote: I like it +7 Vote: I do not like it

Delayed for 4 days. "Big drama show".

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8 years ago, # |
  Vote: I like it +53 Vote: I do not like it

Before Contest 00: 47: 10

Refresh

Before Contest 4 days

Had to check couple of times whether I was seeing it right.

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8 years ago, # |
  Vote: I like it +1 Vote: I do not like it

Issues issues and more issues. Last time with the copied problems thing, I thought of posting a comment regarding the issues that have taken place with CF in the last 3 months.(8+ issues).

However, I shall not post any disrespectful comments as anybody at Codeforces is not answerable to us, but this rising number of issues is very difficult to deal with to say the least.

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

NOOOOOOOOO , :'(

Urgent information from MikeMirzayanov : due to hardware issues, the round will is moved to Tuesday 6th December, 17:35 UTC. We are very sorry this happened. More information will be available later.

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8 years ago, # |
  Vote: I like it +45 Vote: I do not like it

Better delayed than long queue/unrated. :)

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8 years ago, # |
  Vote: I like it -50 Vote: I do not like it

LETS BOYCOTT CODEFORCES FOREVER FOR "BEING ISSUEFORCES"

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

StayStrongCodeForces

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8 years ago, # |
  Vote: I like it +11 Vote: I do not like it

oh mike, faz isso com nois nao, senao nois te quebra

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

Sad because of delay(

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

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8 years ago, # |
  Vote: I like it -18 Vote: I do not like it

কেনে চলর?

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    8 years ago, # ^ |
      Vote: I like it -15 Vote: I do not like it

    :D ঘুম থেকে উঠে দেখি কন্টেস্ট শিডিউল চেঞ্জড !! এমন রাগ উঠছে :@

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8 years ago, # |
  Vote: I like it +4 Vote: I do not like it

IT SEEMS CODEFORCES SERVER HAS GOT IMPROVED AFTER THE UPDATE OF DELAY

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8 years ago, # |
  Vote: I like it +15 Vote: I do not like it

At least site is working and we are not seeing "...due to some hardware issue, CF will be unavailable until 10 January 2017"

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8 years ago, # |
← Rev. 3   Vote: I like it +7 Vote: I do not like it

Deleted

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8 years ago, # |
  Vote: I like it +66 Vote: I do not like it

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    8 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    This needs an edit for Mike as Wojak. There are already real life memes, after all.

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

GET WELL SOON CF!!!

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8 years ago, # |
  Vote: I like it +10 Vote: I do not like it

Actually, computer scientists from codeforces developed some way to time-travel. But due to hardware issues, they could not go back to now. :)

I prepared a bottle of caffine drink and luckily I just took a little sip of it. I think I can sleep tonight.

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

Make Codeforces great again. ._.

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8 years ago, # |
← Rev. 3   Vote: I like it +10 Vote: I do not like it

Hardware Issues :P

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

:S :S

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

:/ I waited and waited whole day for the contest!! now I change the sentence- I wasted and wasted whole day for the contest :'(

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

    you should try another platform like Hacker rank, Hackerearth, lightoj, uva, code chef etc if you are eagerly interested in contest :)

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      8 years ago, # ^ |
        Vote: I like it +9 Vote: I do not like it

      Codeforces contest is another thing bro :'( I can't feel any other contest like cf :(

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Till now the most frequent comment was "Is it rated ?"

Now it'll be "Will it be delayed?" or "I hope it won't be delayed" or "Is the hardware ok?"

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

since the contest is 4 days delayed, I think there'll be higher number of registrations and thus more participation!

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

    ooohhh...nice :)

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      8 years ago, # ^ |
        Vote: I like it -13 Vote: I do not like it

      just 'ooohhh...nice :)' and you got more upvotes than me? Not I want any upvotes.....but seriously!!

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Where is Chinese?

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    8 years ago, # ^ |
      Vote: I like it +15 Vote: I do not like it

    If you are talking about Chinese people, they are everywhere man. Even you are Chinese! LOL :P

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

http://prntscr.com/derzh8 OWF(t=1) ? What.

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8 years ago, # |
  Vote: I like it -10 Vote: I do not like it

I don't feel good about this contest.

first it was postponed and second JESUS CHRIST did anybody read the comments on this blog ??? someone should delete them this is codeforces for god's sake...unless god is participating in the contest do not bring up religious talks here there are a ton of sites for that.

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

Arpa you are going to make record for highest registration may be participation also

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8 years ago, # |
  Vote: I like it +25 Vote: I do not like it

I hope today it won't be delayed again..

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8 years ago, # |
  Vote: I like it +12 Vote: I do not like it

I was on a trip when the Contest was held but then I got home and it had been moved... so happy ^^!

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8 years ago, # |
  Vote: I like it +12 Vote: I do not like it

Good Luck

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Is this going to be the largest CF Div 2 in terms of registrations? Any Pinch on statistics?

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    8 years ago, # ^ |
      Vote: I like it +17 Vote: I do not like it

    For now the largest Div 2 contest had 8497 registrants, but only 7965 of them were really Div. 2 contestants. So, this was already beaten earlier today.

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    8 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    It better be the largest in terms of participation :)

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

What if there are 8500 participants :O

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8 years ago, # |
  Vote: I like it +17 Vote: I do not like it

Scoring Distribution ?

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8 years ago, # |
  Vote: I like it +26 Vote: I do not like it

What's up with the long queues -_-

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8 years ago, # |
  Vote: I like it +6 Vote: I do not like it

The queue is killing me T_T

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

In Queue :(

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

For > 5 minutes my submission is in the queue...

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

I've locked a problem but it won't allow me to see other people's submissions, why?

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8 years ago, # |
  Vote: I like it +7 Vote: I do not like it

Merhdad's girlfriend's reaction (if he has) to problem D (and the word "Hos" that he calls girls with) must be interesting!!!

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    8 years ago, # ^ |
      Vote: I like it +23 Vote: I do not like it

    Which girlfriend you mean? he has many ...

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      8 years ago, # ^ |
        Vote: I like it +7 Vote: I do not like it

      anyone that he cares about(if he does)!! i hope his GF(s) & crush(es) won't be programmers or CF users :D did you two guys even think about anything else except girls when you were preparing this problems?! :D :/

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        8 years ago, # ^ |
          Vote: I like it +4 Vote: I do not like it

        They are CF coders as well, like bogjse316.

        No, but note that I was writer of all of problems ; )

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          8 years ago, # ^ |
            Vote: I like it +6 Vote: I do not like it

          and one more reason(*) to wish that she hasn't a CF account!!
          * -> he(Merdad) has a handle with such a name! -_-
          is there any easy way to be an Arpa's land citizen?! :D

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            8 years ago, # ^ |
              Vote: I like it 0 Vote: I do not like it

            bogjse316 is his girlfriend.

            It's too hard to become an Arpa's land citizen, your DNA must have same pattern as mine, in fact you must be a ... (more information here : 741E - Arpa’s abnormal DNA and Mehrdad’s deep interest).

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              8 years ago, # ^ |
                Vote: I like it 0 Vote: I do not like it

              so it seems like they are in a relationship since at least one year ago :))) (Hos) huuum, so it means that i must be gay?

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                8 years ago, # ^ |
                  Vote: I like it 0 Vote: I do not like it

                As I said, Mehrdad has many girlfriends, some of them are new (less than one year in a relationship) and some of them are old (more than one year in a relationship). And you are right, that Hos (bogjse316) is his loyal and official girlfriend.

                I can't find the relation between Mehrdad girlfriends and you being gay :/

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

                  Being the "sogoli" of your own "haramsara" is such a fun thing! :))

                  Being gay was not about Mehrdad's girlfriends it was about the citizenship.

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                  8 years ago, # ^ |
                    Vote: I like it 0 Vote: I do not like it

                  Ohom.

                  Excuse me, but why you think I am a homosexual ?!

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                  8 years ago, # ^ |
                    Vote: I like it 0 Vote: I do not like it

                  I just guess :)

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                  8 years ago, # ^ |
                    Vote: I like it 0 Vote: I do not like it

                  Don't publish your guesses publicly. Let's move to private messages, shall we?

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8 years ago, # |
  Vote: I like it +10 Vote: I do not like it

Too many girls in problem statements :D Arpa ?

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8 years ago, # |
  Vote: I like it +22 Vote: I do not like it

I am the god of lock problems...

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8 years ago, # |
  Vote: I like it +24 Vote: I do not like it

Awesome problems, guys!

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    8 years ago, # ^ |
      Vote: I like it +23 Vote: I do not like it

    Thanks. Wait for unique editorial as well :P

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

I wish I had hacked myself. T__T

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    8 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    I wish the same. Was hacking someone then realized that I myself missed a case.

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8 years ago, # |
  Vote: I like it +14 Vote: I do not like it

To be honest the contest isn't interesting, speed contest, first 2 are easy the rest hard ((.

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8 years ago, # |
  Vote: I like it +11 Vote: I do not like it

Hack case for Div 1A :
Make simple cycles of odd lengths, i.e each node belongs to exactly one cycle of an odd length.
Using 99 nodes, you can make simple cycles of lengths 3, 5, 7, 9....17.
The answer for such a case would 14549535.

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

I hacked 6 and got hacked...maybe next time I should try to solve E...

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Is O(nk2) dp the intended solution for Div1-B?

And how to solve C?

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8 years ago, # |
  Vote: I like it +6 Vote: I do not like it

Is div1 C 2-SAT?

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    8 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    I don't think so, at least not my solution...

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    8 years ago, # ^ |
      Vote: I like it +29 Vote: I do not like it

    Solution : Draw an edge between each pair of couples and also draw an edge from vertex 2i + 1 to 2i + 2 for all i. This graph is bipartite since it has no odd cycles. Thus, we can 2-color it and it is easy to see that this satisfies all problem conditions. GG

    Note : I didn't solve it during contest T_T

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      8 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      "This graph is bipartite" ?

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        8 years ago, # ^ |
          Vote: I like it +21 Vote: I do not like it

        The graph is sum of two maychings so it is biparitie!

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      8 years ago, # ^ |
        Vote: I like it +11 Vote: I do not like it

      So we add edges between 1-2, 3-4 and so on. But isn't this forcing the condition that the type of foods by the people at 1st and 2nd position should necessarily be different? Can't there be a solution when both eat the same type of food (unless every case of that type can be converted to one in which they eat different foods)? I am unable to understand this.

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8 years ago, # |
  Vote: I like it +32 Vote: I do not like it

Worst feeling known to humanity: the realization that your solution is wrong after locking the problem

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    8 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Oh, same here! For some reason, I forgot that I couldn't submit anymore and thought I had found some pretty cool cheat. My idea was to open the source of the one who hacked me, then rewrite it myself and submit it. It sounded brilliant to me until I tried to submit it :D :D :D My biggest facepalm ever, something strange happens with me these days :D

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8 years ago, # |
  Vote: I like it -14 Vote: I do not like it

Hello sorry but for further contests i believe you need to be more specific about what you want in the problems for example in problem B div2 when you say pairs, you don't say distinct pairs or plain pairs, example input does not help to clarify this and this could lead to unnecessary wrong answers. (not in my case since i had it all wrong but you get the idea)

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

    in the statement 1 <= i < j <= n

    this is the same as saying that they are distinct pairs

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    8 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    I think there were some mathematical thing that says what it want after the word pair. It's quite clear to me tho.

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

Any hack for problem C.

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

I'm new here. Pardon me if I say something irrelevant. Will the explanations of the problems be given after the contest? :/

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

    Yes, the editorial will be posted within few days :)

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      8 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      Thank you very much mister ^_^ can you help me with another thing? What is "hack" that everyone keeps talking about?

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        8 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        There are a set of tests called pretests which your submission is tested on during the contest. These tests aren't entirely comprehensive so your solution could still be wrong even if it passes the pretests. After passing pretests, you can "lock" your problem (meaning you can no longer resubmit it) and then you're allowed to look at the code of other people in your room (everyone is assigned a room in the beginning of the contest). If you think someone's code is wrong, you can give it a counter test case and if it is wrong, then you get an extra 100 points but if your test case is wrong, you lose 50 points.

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

I saw someone in my room successfully hacked 10 times.(div 2)....

And now I'm thinking about my life.

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Does Div2C/Div1A has anything to do with floydWarshall ?

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    8 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    No, just find all the cycle lengths and calculate the LCM. Beware cycles with even length.

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      8 years ago, # ^ |
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      I'm confused about how you came up with that. Did you just notice a pattern or is there some kind of reasoning for why that's the solution?

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

        First, notice that all nodes must be within cycles (a node outside a cycle can't be reached by any of the nodes he reaches, by cycle definition, so we'll never satisfy the property of the problem).

        Then, considering a and b in the same cycle, the only way to satisfy a --(t steps)--> b and b --(t steps)--> a is if a == b (and then t = size of cycle) or if b is halfway from a on the cycle and a is halfway from b on the cycle (and then t = half the size of cycle) — which is only possible if cycle length is even.

        So cycles of even length will satisfy the mentioned property when t is multiple of length/2, cycles of odd length will satisfy the property when t is multiple of its length. And then the LCM of these will give the minimum t where the property is satisfied for them all :)

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

I can't even code knapsack!

Wrote i++ instead of j++ . Literally 1 character mistake. ;_;

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Can not believe C was solved by a lot of people. Maybe I understood in a wrong way.

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8 years ago, # |
  Vote: I like it +1 Vote: I do not like it

Problem A and B sooo hackable! For A problem! in
0 out 1 For B problem! in 2 0 1 1 out 1 But someones' answer 2

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

I'm not too sure, but I suspect that the girls in Arpa's land are attractive to look at.

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8 years ago, # |
  Vote: I like it +86 Vote: I do not like it

While B was too easy and boring (I even spent some time re-reading the statement two times to see what I missed), problem C was very nice. And it may be argued but I would write "note the unusual constraint for the alphabet size" in problem D because it was extremely easy to miss (and it's indeed very unusual constraint). Thanks for a nice contest!

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    8 years ago, # ^ |
    ← Rev. 2   Vote: I like it +34 Vote: I do not like it

    So what's your complexity about problem D?

    UPD: Oops, I didn't see this constraint during the contest, and implemented a hash table.

    BTW, the time complexity of my solution is . If this solution is expected, I think the it's better to set small N.

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    8 years ago, # ^ |
    ← Rev. 2   Vote: I like it +35 Vote: I do not like it

    I don't see why author didn't remove that constraint and put memory limit of 512MB (or smaller N so that hashmap can be used). It would look much better.

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      8 years ago, # ^ |
        Vote: I like it -31 Vote: I do not like it

      Actually that is a very good question. Originally that was a problem C and I had the same comment in the system during presolving as you have. But when the problem became D we all agreed that having this technical difficulties should be great for D.

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8 years ago, # |
  Vote: I like it +22 Vote: I do not like it

Arpa, why did you hide your article "DSU on trees"? Still available with google cache :) I guess Div1D can be solved with it (though I didn't manage yet).

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    8 years ago, # ^ |
      Vote: I like it +21 Vote: I do not like it

    Yes I've hided that. And the solution uses this technique.

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8 years ago, # |
  Vote: I like it +25 Vote: I do not like it

enot110 has a very interesting solution for Div 1C...

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    8 years ago, # ^ |
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    It is just random solution. Most of the solutions have been like this.

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8 years ago, # |
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the hacking round....

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8 years ago, # |
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Can anyone tell me why my solution to problem B is wrong? (it got wrong answer on pretest 11):

long long int count_anwser() { long long int ans = 0; for(int i = 0; i < numer_of_elements; ++i) { int needed_number = tab[i]^x;

ans += count_of_this_numer[needed_number];
    count_of_this_numer[tab[i]]++;
}
return ans;

}

where count_of_this_numer is number of elements which are equal to index

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

    Value of needed_number can be greater than 1e5.

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      8 years ago, # ^ |
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      Ohhh, I lost 30 min to figure out what was wrong, now Accepted :(

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8 years ago, # |
  Vote: I like it +14 Vote: I do not like it

Interesting problems accompanied by a super fast system testing. Thanks for the nice contest guys :)

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8 years ago, # |
← Rev. 5   Vote: I like it -27 Vote: I do not like it

I solved problem div2 D using this technique [ DSU + 0-1 knapsack + dp ]:

  1. make groups with DSU

  2. With the 0-1 knapsack, take the max of:

    i) try to invite each group whole

    ii) try to invite a single person of this group(try with each member)

    iii) don't invite anyone at all

  3. store the max in dp and return it

What's wrong in my algorithm or in code ?

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Can problems of the type of Div1C in general have flow solutions? I know here n ≤ 105, but I'm interested to know if these problems where every k consecutive people satisfy some property can be solved with flow.

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8 years ago, # |
← Rev. 2   Vote: I like it +64 Vote: I do not like it

In problem D, the constraint that all letters are between 'a' and 'v' is very well hidden in the input section and not emphasized at all. I'm pretty sure it cost Swistakk an Accepted on it, and it cost me a submit and half an hour more to implement it.

I think such unusual constraints should be highlighted because it's very difficult to spot them otherwise.

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    8 years ago, # ^ |
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    I don't know why you mentioned me, but my code was just a bit too slow (and memory consuming, but that can be fixed with one line). I really dislike that problem, it is rather obvious what is the solution and whole "fun" is winning with strict TL what is dependent on details of implementation :|.

    However, indeed I had an idea to create a static array of size 2|Σ|, but 226 was too much. Either way, I needed to create such arrays, so I needed |Σ| ≤ 21, 22 was still too much :D.

    And yes, I definitely agree with your point, that constraint was extremely easy to miss, it should have been emphasized.

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      8 years ago, # ^ |
        Vote: I like it +10 Vote: I do not like it

      I saw you got MLE, so I glanced through your code and saw you had 26 and 27 in your code so I thought you didn't see the constraint like me xD.

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8 years ago, # |
← Rev. 5   Vote: I like it +49 Vote: I do not like it

Two non-similar codes 22748780 and 22758461 from the same country.

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    8 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    I'm feeling sad about that. I belive they will be banned and will learn the lesson in a hard and expensive way.

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8 years ago, # |
  Vote: I like it -15 Vote: I do not like it

i think there is a mistake in problem D on DIV2 int the statement you say " Along with that, from each friendship group he can either invite all Hoses, or no more than one" you didn't say that i can take no one from this group

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    8 years ago, # ^ |
      Vote: I like it +18 Vote: I do not like it

    "no more than one" implies that you can take <=1 people.

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

What is the intended time complexity of D and E? O(Nσlog N) in D and O(Nsqrt(Nlog N)) in E?

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8 years ago, # |
  Vote: I like it +19 Vote: I do not like it

me when i see a girl from Arpa's land :3 :3 :v

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8 years ago, # |
  Vote: I like it +125 Vote: I do not like it

What is the reasoning behind problem E?

I understand the first part. The quite obvious idea of sorting implicit strings with hashes is not brand new and (usually) not very pleasant to implement, but nevertheless, it is OK for Div1E.

I understand the second part. The quite obvious idea of splitting K-s into small and large and answering queries in is not brand new and (usually) not very pleasant to implement, but nevertheless, it is OK for Div1E.

And now, if you think that it is really interesting to combine two completely unrelated to each other nasty idealess implementations into one Div1E problem, be the first to throw a stone at me.

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    8 years ago, # ^ |
      Vote: I like it +13 Vote: I do not like it

    Firstly, I agree that the problem isn't very imaginative. However, I think as far as difficulty goes, it deserved to be where it was, seeing as only anta solved it in contest — I found it very hard to code it in 2 hours and only solved it afterwards. I do understand your point though.

    Secondly, the complexity you mentioned for queries isn't fast enough. Instead we need to use both range trees (for K<=50) and sparse table (for K>50 so that N/K <= 2000). However, this does actually prove your point about how it was nasty to implement.

    So I agree that it wasn't beautiful as you would expect for a Div1E, but I would argue it isn't too trivial to 'see' the solution either.

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      8 years ago, # ^ |
      ← Rev. 2   Vote: I like it +28 Vote: I do not like it

      I use overall complexity for queries and get AC.

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        8 years ago, # ^ |
          Vote: I like it +10 Vote: I do not like it

        Ah, I didn't think of your algorithm (which has lower constant factor than what I was thinking) — it's quite beautiful. :D

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        8 years ago, # ^ |
          Vote: I like it -20 Vote: I do not like it

        It was allowed, I had a as well. What is the problem ?

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    8 years ago, # ^ |
      Vote: I like it -10 Vote: I do not like it

    Sorry, I skipped your comment suddenly because I was busy that time.

    Note that hashes are not allowed. I had banned solution with hashes, if you use mod = 2x, you'll get wrong answer, otherwise, you'll get TLE because modulo operations.

    Why you want to mock my problem? Let's talk more in privet messages, shall we?

    (Thanks to Errichto, I was writing a mocking comment because I was angry, he told me not to do)

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8 years ago, # |
  Vote: I like it +1 Vote: I do not like it

I want to go to Arpa Island. ♥

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8 years ago, # |
  Vote: I like it +6 Vote: I do not like it

Hello,

Could someone help me with a little explanation?

I tried to hack this code for problem B during the contest:

http://pastebin.com/TJHFm3s8

I was expecting it to give runtime error since there is an array out of bounds access on the test that I've provided (you can see there is truly such an access if you comment out the cout... it will try to access the array at position 131071 but the array is only 100005 long). However, even though there's an out of bounds access it doesn't give runtime error. Can someone explain why?

Thanks in advance.

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    8 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    I guess it depends on the compiler.
    You can test cf compiler here: http://codeforces.net/problemset/customtest
    Here is my conclusion after testing:
    If the array is declared in global, then out of bounds will print 0. However , If the array is declared in the function, out of bounds will give run-time error.

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      8 years ago, # ^ |
        Vote: I like it +4 Vote: I do not like it

      That's not true either. I have seen codes which declared the array globally and got RE (my own code does that if I comment out the line which checks this).

      It really doesn't seem fair to me that some sources got accepted with this problem while others got RE for the same issue. Applied to hacks as well (especially to hacks). Haven't seen this happening on any other online judge.

      Oh well.

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

    There is also a variable 'b' with size 100.000. Variable 'a' is a pointer and when you access a[ 131.071 ], you basically access a + 131.071. 'b' is allocated after 'a' so you will access b[ 31.071 ]. Not sure if this works only on global variables but i think this is something that depends on the compiler and language. If you would access a[ 250.000 ] ( this will be equal to b[ 150.000 ] i guess ), that will go out of every variable and that should give runtime error.

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

      Thing is you access b[131K].. not a[131K]. And b is declared after a.

      At any rate... we can speculate on this all we want but the truth is array out of bounds is classified in C (and C++) as undefined behavior. Which means we can speculate all we want but the details of this are compiler-specific.

      Therefore, the CF crew is not at fault here. It's just sad that some people got accepted with a bug in their code while other people got RE on the same bug. But oh well, what can you do ¯\_(ツ)_/¯

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

Same code but why RE for using Array and AC for using map (STL). [problem:][problem:742B] RE: 22763251 AC: 22763425

All data set <= 100000. i am used 100005 in array size. but got RE. why?????????????????? Explain please.

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Can anyone help me in Div2 B?

I first sorted the given array, then if a^b=x then b=x^a. Since it is sorted I can find out the number of occurrences of b in the array by upperbound-lowerbound. (I checked for non occurrence seperately).

Thank You.

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

    You overkilled it. Just count xxorai. Array is enough. Keep in mind that size of array must be greater than 105 since xor can be greater.

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      8 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      Thank You! I got an AC with this method. But still, although I know my solution is an overkill, it should give correct answer right?

      Here is the link of my solution : http://codeforces.net/contest/742/submission/22764097

      Thank You once again :)

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

        Overflow.

        In ans = ans + ub - lb;, address of ub will be added to ans which might cause overflow.

        So change it to ans = ans + (ub-a.begin()) - (lb-a.begin()); or ans = ans + (ub-lb);

        Accepted

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          8 years ago, # ^ |
            Vote: I like it 0 Vote: I do not like it

          Thank You so much!

          Never once thought of overflow. Will have to take care not to repeat it again. Thanks :)

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

In div1A and div2C pretest 4 is as follows

5

2 4 3 1 2

In this wouldn't the ans be 3 as 1 calls 2. Then 2 calls 4. 4 calls 1 giving t=3

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

    5 calls 2, 2 calls 4, 4 calls 1, 1 calls 2, 2 calls, 4,...
    The cycle keeps on going, but will never return to 5. So ans is -1

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      8 years ago, # ^ |
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      Ahh got it. I missed that 'each' x. This means that every node has to be in a cycle. Thanks.

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

    No, the answer will be -1 because 5 will never be called. 5 calls 2 and 2 is a part of a loop 2->4->1->2. The number t should be satisfied for all x and it isn't satisfied for x=5.

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8 years ago, # |
  Vote: I like it +64 Vote: I do not like it

Finally I'm green :)

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8 years ago, # |
  Vote: I like it +12 Vote: I do not like it

Where's tutorial?

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8 years ago, # |
  Vote: I like it +29 Vote: I do not like it

I think today's problemset(Div.2) was awesome. One of the best contests in Codeforces in recent times by far.Though my own performance wasn't the coolest, but really got inner peace just by thinking and formulating the solutions. :P :P. Thanks to the authors and co-ordinators. Great job guys. :D :D

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

Two code are same . In the problem B constraint for 1 ≤ ai ≤ 100000 . IN one code I used frq array for frequency got WA on 11 . But when i USed MAP for frequency , then got AC . That means constraint for ai is not correct . My two submissions are 1) With MAP frq 2) With frq array .

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    8 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    As stated above by OMG_wc
    "arr[i]^x >100000 99999^25655=123560"

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    8 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    XOR of two numbers a,b <= 10^5 can be greater than 10^5 . That's why using an array fails . Map just stores 0 for a key which is not present .

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

LARGEST NO OF COMMENTS ON ANY CONTEST ANOUNCE'' PAGE jqdai0815 >Petr

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Whats special with even cycle in Div2 C? why we need to half them ?

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

    In an odd cycle, the only way that if the round of X ends in Y then the round of Y ends in X with a certain t, is if X=Y. Nevertheless, if the cycle length is even, it can Y can be the "midpoint" of the X cycle. Think of the following case: 2 2 1 (Sorry, I don't know how to format the test case properly)

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

how to do div2 E

first you must know -1 is impossible.

then you can do such thing

while(1){
check if 3 same
if same,then random 1-3 ,and swap him with his wife.
if you do 2n times and find everything fine,then break
}

here is code 22763097

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8 years ago, # |
  Vote: I like it +39 Vote: I do not like it

Really outstanding contest!

Short problem statements, elegant pictures for every problem, interesting legend and such a extraordinary editorial. After this contest I feel a very pleasant aftertaste, because I see that every effort was made to make this contest brilliant. And it is.

I feel satisfied. Thank you a lot.

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8 years ago, # |
  Vote: I like it +1 Vote: I do not like it

had a nice starting for the problems "arpa land has very nice girls" :D

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

Could someone help me debug my solution? http://codeforces.net/contest/742/submission/22769800
thank you!

EDIT: I found the mistake, if anyone was wondering it's accessing the array with i%2, those arent the iterations of the dynamic but the index of the group.

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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

i wanna make deeeeeeeeeeeeeeeeeeeep replays

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