YouKn0wWho's blog

By YouKn0wWho, 5 weeks ago, In English

আবার চলে এসেছি! (That's Bengali for "I am back! (in Terminator mode)")

I am super excited to invite you to participate in Codeforces Round #752 (Div. 1) and Codeforces Round #752 (Div. 2) which will be held on Oct/30/2021 17:35 (Moscow time). This round is rated for both divisions.

You will be given $$$6$$$ problems in each division and $$$2$$$ hours to solve them. All the problems are authored and prepared by me.

I would like to thank -

The statements are short and directly ask you what to do and I have tried to make the pretests strong. I highly encourage you to read all the problems.

Solve problems and help the poor! Yes, you heard it right, this time you can help the world by just solving problems. I will donate money based on the solve count of each problem by the following measure:

Donation Per AC

The total estimated money is half of what I will get from Codeforces for this contest(but you can make it more by just solving more problems!). I am a student, so pardon me if that's too little.

Also, did you know that you can still upvote my The Ultimate Topic List blog and make it to the top?

Finally, I would like to dedicate this contest to me! I want to thank me for believing in me, for doing all this hard work, for trying to do more right than wrong. I want to thank me for just being me at all times.

Score distribution:
Div.1: $$$750-1000-1750-2500- 3500-3750$$$.
Div.2: $$$500-1000-1750-2000-2750-3500$$$.

Good Luck! Love you blobheart.

UPD: Editorial

UPD: Congratulations to the winners.

Div.1:

  1. tourist
  2. djq_cpp
  3. Petr
  4. DmitryGrigorev
  5. ecnerwala

Div.2:

  1. Rolling_Code
  2. Pecans
  3. fangzhijina2020
  4. whtdsjmr
  5. Graphcities

UPD: Here is how the donation amount looks like:

Donation

FYI I will get 400 USD for this contest. So the donation amount is indeed half of this as I have estimated before the contest, although didn't think that it would be this accurate.

I will update you again when I get the money from Codeforces, more likely after a few months as I haven't received my previous contest's payment yet which happened 3 months ago!

Also, thanks for being a part of this. You have just helped someone who is in need (I mean after I distribute the money).

 
 
 
 
  • Vote: I like it
  • +3156
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5 weeks ago, # |
  Vote: I like it +103 Vote: I do not like it

Donation per AC!! Just loved it. Proud of you vai ♥

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

    Exactly bro ! I just got surprised that how this man comes with such a amazing idea.

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

      He should reveal how and where he's donating the money. It's just as important to know that the money will be utilized in the best possible manner.

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

no funny text this time? :P

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5 weeks ago, # |
  Vote: I like it -40 Vote: I do not like it

"0.005 USD" WOW THANKS MR.GENEROUS

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

    I see your negative comments almost in every recent blog posts. Seems like you have opened this account just to pass rude comments!

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5 weeks ago, # |
  Vote: I like it +37 Vote: I do not like it

If someone can help the poor just by solving problem, that's gonna be more fun!! :D

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

Yet another great round is coming ! :D

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

Great Initiative

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

That's great Shohag. Hope everyone will enjoy this contest.

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

Wow, that's great. Hats off to you.

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

Proud of you, bhai. <3

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

Super excited for a Bangladeshi round again!! :D

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

Very Good idea for helping poor people. Thanks for this contest. I am so happy that I can help poor people.

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

Hope for 2K upvotes and Rank #1 in top contributors.

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5 weeks ago, # |
  Vote: I like it +130 Vote: I do not like it

:(

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

Inviting the fellow programmers to be the part of this initiative....

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5 weeks ago, # |
Rev. 4   Vote: I like it +11 Vote: I do not like it

Let's send YouKn0wWho vai(brother) to the Mars by upvoting.

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

    Sorry but I think we should go to the sun and not Mars

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

এভাবেই বারবার চলে আসবেন ভাই ♥♥

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

Very excited to praticipate of a bangladeshi round.

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

Donation per AC!! Too good to be true.

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

Again , pari na pari khela hobe :3 (it means i will must participate ,dont downvote)

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

Your last round was extremely good. I hope this one is as well.

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

    That was a tough Math round

    how many did you solve or you like the testcases

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

      I solved A,B, I think in contest, and upsolved C and D.

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

For a moment I thought why the blog has only 166 upvotes(previous round announcement has more than 1600) then I realized that you are back with a new round .

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

Really looking forward for this one after the last round. Also props on the idea for donations <3

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

Super excited Vaia. Take Love.

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

Unusual contest time has become so usual in CF these days! So,now it's over :")

  • Hope to solve at least one problem in this round :)
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5 weeks ago, # |
  Vote: I like it +61 Vote: I do not like it

Codeforces Round #752, writer: YouKn0wWho

Spoiler
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5 weeks ago, # |
  Vote: I like it +31 Vote: I do not like it

As a tester, these are some of the coolest problems I've encountered in quite some time. So if you're going to participate, you're in for a treat!

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5 weeks ago, # |
  Vote: I like it +55 Vote: I do not like it

as a tester, I would say the problems seemed very cool to me. don't dare to miss the contest and the potential high rating! Good LUCK all!

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5 weeks ago, # |
  Vote: I like it -25 Vote: I do not like it

Woah, awesome initiative! :)

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

just curious.. how much does codeforces pay one for setting up a contest?

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

    look at this
    This contest is Div1+2 then CF will pay 400 USD.

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

      Actually i was trying to estimate the total amount and it came up around 350+ dollars. Damn, i should have seen this comment from the start.

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5 weeks ago, # |
Rev. 3   Vote: I like it +48 Vote: I do not like it
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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

look for another xor contest

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

Hyped for more anime references in the questions lol

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5 weeks ago, # |
  Vote: I like it +34 Vote: I do not like it

So if I participate from Div1 and solve all problems, you donate 6.255 USD, that's nice. But that's too tough, I'll just donate 7 USD myself instead.

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    5 weeks ago, # ^ |
      Vote: I like it +108 Vote: I do not like it

    I thought you stopped being a nerd.

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    5 weeks ago, # ^ |
      Vote: I like it +79 Vote: I do not like it

    Or better.. I'll donate 7 USD, so give me solutions to submit during contests. :catThink:

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      5 weeks ago, # ^ |
        Vote: I like it -40 Vote: I do not like it

      Okay this is bad, now we're plane selling and buying solutions.

      (give me some I'll give you 14 USD)

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    5 weeks ago, # ^ |
    Rev. 2   Vote: I like it -39 Vote: I do not like it

    Deleted

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

    good to see u back

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5 weeks ago, # |
Rev. 2   Vote: I like it +241 Vote: I do not like it

dorijanlendvaj for providing a test case which will potentially prevent few wrong solutions from getting AC.

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    5 weeks ago, # ^ |
      Vote: I like it +34 Vote: I do not like it

    I don't have any say over whether it will be in pretests, YouKn0wWho just asked "Is there a test case that accomplishes [REDACTED]?" and I responded with a test case that does.

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

      Right! i wasn't sure who had a say. I've updated the image now :P

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      5 weeks ago, # ^ |
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      Just out of curiosity, What test case of which problem it was?

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

        It was a test case for long long overflow if modulo is only taken at the very end in div1C.

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

Another BD Contest(উফস মজাই আলাদা). Proud of you bro❤️

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5 weeks ago, # |
  Vote: I like it +102 Vote: I do not like it
lighthearted meme
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5 weeks ago, # |
  Vote: I like it +1 Vote: I do not like it

Eagerly Waiting

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5 weeks ago, # |
  Vote: I like it +14 Vote: I do not like it
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5 weeks ago, # |
  Vote: I like it +1 Vote: I do not like it

Hello everyone. Good luck to everyone on the contest and a good rating!

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

Finally, I would like to dedicate my participation in this contest to myself, for doing all this hard work, for trying to get to Expert. I'm just so grateful to myself for being me at all times.

<3

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

♥ ♥ ♥

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

osthir vai <3

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

Positivity Everywhere!!!

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5 weeks ago, # |
  Vote: I like it +102 Vote: I do not like it

This is the first time cheaters will actually do something good to this community lol

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

for the line with dorijanlendvaj, I think you should say 'potentially prevent a few' since saying it will prevent few solutions from AC essentially means the test case doesn't do much. saying it will prevent a few solutions from AC means the test case will do some stuff. yes, adding one word changes the meaning english is weird

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

but what happens if someone leaks div2F and 1000 people copy it

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

    the good deeds

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

    Their excuse would be "I just want to help and give back to the community, so we did this for a good cause so please forgive us Mr. Mike"

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

Masha Allah

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

Last contest by YouKn0wWho, I gained 125 points. To date, it was my best contest ever.

Update: Candidate Master this time

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5 weeks ago, # |
  Vote: I like it +287 Vote: I do not like it

Should we be concerned that the author has a monetary incentive to make weak pretests?

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    5 weeks ago, # ^ |
      Vote: I like it -66 Vote: I do not like it

    Nah I think we should be more concerned that your rule might be coming to an end.

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    5 weeks ago, # ^ |
      Vote: I like it +36 Vote: I do not like it

    I guess if he had any monetary incentives, he would prefer not to introduce a donation system at all

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

      That's not fair. The donation system is the political move that dethroned 1-gon!

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

    No

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

    Should we be concerned my words have come true?

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

      Yes, we should be celebrating the new ruler.

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

        I honestly can't tell if you are being humble or trying to get upvotes. Let's stick with the former.

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

        Yes, everyone here is great

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

Thanks for the generosity and look forward to this round!

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

Hope I can donate more than 0.02 in this round :D

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

I hope this will be super exciting contest like here

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

So you're gonna be ligend!!

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

Notice the Usual Timing of the contest.

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5 weeks ago, # |
  Vote: I like it +9 Vote: I do not like it
YouKn0wIt
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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

looking forward for an amazing contest!

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

I usually don't comment on blogs but your initiative is heart winning :)

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

Deleted

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    5 weeks ago, # ^ |
    Rev. 2   Vote: I like it +17 Vote: I do not like it

    False, IIT BHU had previous div1 rounds

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

      Ashishgup is not the authors of the round you mentioned

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

        yup sadly he dont but in the upcoming days he will have :) , anyways still false manthan by IIT Bhu was div1 rated in past.

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

this might be the best thing I have ever seen in my life....thanks a lot dude..

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

Okay, after reading the full passage, i am getting more positive vibes about the contest.

Looking forward for a great contest and a motivation to keep me going.

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

Poor-force will help me come to master this time

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5 weeks ago, # |
  Vote: I like it -27 Vote: I do not like it

1-gon are you scared of YouKn0wWho??

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

অপেক্ষায় আছি, ভাই।

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

problem A was easy of round Div2

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

Second time participated in your round! Love it.

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

YouKn0wWho is one of the best setters I know in Bangladesh.

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

Again 1k+ upvote Sohag brother ........ <3 Keep ahead

Hopefully #752 will be interesting

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

Good luck too all :)

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5 weeks ago, # |
Rev. 2   Vote: I like it -16 Vote: I do not like it
ignore if you don't like memes
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    5 weeks ago, # ^ |
      Vote: I like it +3 Vote: I do not like it

    You mean upvote more? coz u shdn't participate with multiple accounts.

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

      Good point

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

      no, I meant Solve one problem multiple times and help the poor. just kidding... I know the rules...

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5 weeks ago, # |
  Vote: I like it -135 Vote: I do not like it

...you can help the world by just solving problems.

That's quite an unique idea! At least for me this is my first time to participate in such contest.

Hope for a great contest!

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

    Why downvotes to his comment?

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

      I also don't see anything wrong in the comment.

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

      Maybe because EasonCF's comments are everywhere and people got fed up with them

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        5 weeks ago, # ^ |
          Vote: I like it +93 Vote: I do not like it

        Exactly

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          5 weeks ago, # ^ |
            Vote: I like it +91 Vote: I do not like it

          But I don't think this can be the reason to downvote a comment.

          I think whether to downvote a comment depends to itself but not depends to the author.

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

            It seems like saying stereotyped words to get contribution but not expressing his/her own words.

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        5 weeks ago, # ^ |
          Vote: I like it +63 Vote: I do not like it

        Appropriate.

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

Why isn't scoring distribution in the same ratio as donation amount ratio?

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5 weeks ago, # |
  Vote: I like it +47 Vote: I do not like it

Where will you be donating the money to?

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

Solve problems and help the poor! <3

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5 weeks ago, # |
Rev. 3   Vote: I like it +41 Vote: I do not like it

As a tester, I recommend the contest to you all. As a contestant upvote the blog, or else ...

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

The statements are short and directly ask you what to do. Thanks for assure it and not to make the statement gazakhori and azaira pechal. :D

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

Thank you YouKn0wWho for keeping the problem direct and short. And your previous blog is helping a lot. ^_^

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

.

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

Apart from the contest it will be more exciting to see YouKn0wWho as the number one contributor ;D

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

number theory — "I am back too" xD btw great initiative ❤️

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

The last round you wrote was very interesting and tough.

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

This is going to be a great round.

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5 weeks ago, # |
Rev. 2   Vote: I like it +27 Vote: I do not like it
Meme
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5 weeks ago, # |
  Vote: I like it +1 Vote: I do not like it

"Donation Per AC". Go ahead with great work vai.

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

Super excited for another Bangladeshi round!! (Started practicing number theory :p)

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5 weeks ago, # |
  Vote: I like it +22 Vote: I do not like it
Meme: It's close
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5 weeks ago, # |
  Vote: I like it +129 Vote: I do not like it

Upd:

Div2B: 0.005 -> 0.006

Div2C: 0.005 -> 0.008

Div1F: 4 -> 2

I hope now the distribution is more consistent with the point values of the problems.

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

Good luck

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

Hope you always be in the first place of top contributors

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

I want to become Grand Master!

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

Super excited

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

well div2 seems to be 1 sec ahead of div1.

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

Great initiative, you are doing a very good job. Thank you!

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

According to the rating predictor for last contest (education 116), my rating will go up to 1905. That means this will be my first time to participate div 1. So excited.

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

it's really good stuff that you are doing with this job, respect!

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

My solution for B here, https://codeforces.com/contest/1606/submission/133495767, fails in test 6. It appears to be some rounding errors. Does anyone know what caused it?

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5 weeks ago, # |
  Vote: I like it +27 Vote: I do not like it

Top contributor!!

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

Hello from Bangladesh! Just loved the concept of donation per AC. Will definitely participate tonight In Sha Allah.

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

I want to take part in this contest but tonight, Liverpool — my favourite football cbub have a match wwith Brighton :(((

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

    I gave contest on the day pakistan beat india for first time in cricket world cups in 29 years . so deal with it .

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

      let me think, I think I can watch the first 30 mins and after that, I join in the contest =)))

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

অনেকদিন পর আজকে পার্টিসিপেট করবো ভাই :) ভাবতেই ভাল্লাগছে...

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

Looking forward to my first Div 1 round!!

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

Alhamdulillah.. Great achievement! YouKn0wWho is now top contributor from Bangladesh. Proud of you man!

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

It is good round!!!

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

Excited for this one as it`s gonna be my first contest on this platform!! Looking forward to gaining some nyc ratings .....

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5 weeks ago, # |
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Proud of you as a bengali.

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

As a Bangladeshi Participants, proud of you bro

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5 weeks ago, # |
  Vote: I like it +175 Vote: I do not like it

Congrats on becoming the new top contributor! Remember, great power comes with great responsibility.

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5 weeks ago, # |
Rev. 2   Vote: I like it +69 Vote: I do not like it

If I'll solve E/F and resubmit it 9 more times, will you donate 20 USD?

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    5 weeks ago, # ^ |
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    But they have to pass the main tests and sadly CF skips multiple AC submissions for each problem :((

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5 weeks ago, # |
  Vote: I like it +79 Vote: I do not like it

This alone made the contest worthwhile YouKn0wWho

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

I locked one of my codes for hacking but I cannot view the locked solutions of other users in my room. Kindly fix it YouKn0wWho

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

Very interesting problems! Thanks to creaters of this contest!

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

    but very strange problem C and I dont know how my solution pass pretests

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

Great problemset, but div2-D was quite easy compared to 2000 rated problems i think.

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5 weeks ago, # |
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lol C was so easy I blundered it yet again

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

D was too easy tbh. C made me realize how dumb I am once again. Nice contest tho

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

    Was it? I spent over an hour staring at it and couldn't come up with solution xD

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      5 weeks ago, # ^ |
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      I think he is talking about div.2 C and D:)

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

        I am pretty sure natofp is talking about Div1B (Div2D) based on his submission time lol.

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

    Took me an hour to do it :|

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    5 weeks ago, # ^ |
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    What approach did you used for D?

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

      Did bruteforce and found the pattern.

      if(x==y)cout<<x<<"\n";
      else if(x>=y)cout<<x+y<<"\n";
      else cout<< y-(y%x)/2<<"\n";
      
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        5 weeks ago, # ^ |
        Rev. 2   Vote: I like it +3 Vote: I do not like it

        To add to this, a little bit more explanation on how I personally came up with $$$y-(y\mod x)/2$$$:

        Suppose $$$x\leq y$$$. We want to find a $$$n$$$ such that there exists integers $$$k,l,b$$$ that satisfy $$$n=kx+b$$$ and $$$y=ln+b$$$ (and $$$b<x,b<n$$$).
        We can see that any valid $$$n$$$ has to satisfy $$$x\leq n\leq y$$$ (*), so $$$k,l\geq 1$$$.
        Expanding $$$y=ln+b$$$, we get $$$y=(lk)x+(l+1)b$$$. This means $$$(l+1)b=y\mod x+ax$$$ for some integer $$$a$$$.

        To construct a valid solution from here, note that since $$$x,y$$$ are both even, we can set $$$a=0$$$ and $$$l=1$$$ (since RHS is also even). This gives in a valid $$$b$$$ and $$$n$$$, which is exactly $$$n=y-(y\mod x)/2$$$.

        (*) To elaborate on why $$$x\leq n\leq y$$$: If $$$n<x$$$, $$$n\mod x=n$$$ but $$$y\mod n$$$ can't be $$$n$$$. If $$$n>y$$$, $$$y\mod n=y\geq x$$$ so it can't be $$$n\mod x$$$.

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

      I found the pattern after bruteforcing testcases, dont know why it works.

      basically if x>=y, ans is x+y, else y-(y%x)/2

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

    Maybe I just happened to figure out the pattern

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5 weeks ago, # |
Rev. 3   Vote: I like it +15 Vote: I do not like it

Thanks for great contest! I was late for an hour because of my classes but still participated in order to help charity!

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

    WOWW.. You might not know it, But man you are a hero.

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

Countforces Round #752

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5 weeks ago, # |
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Problem 1604C - Di-visible Confusion is logical problem ...... I didn't solve this.

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

    Did bruteforce and found the pattern.

    if(x==y)cout<<x<<"\n";
    else if(x>=y)cout<<x+y<<"\n";
    else cout<< y-(y%x)/2<<"\n";
    
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5 weeks ago, # |
Rev. 2   Vote: I like it +8 Vote: I do not like it

How to get rid of TLE in pretest 5 in div1C?
I needed to get the possible next numbers can appear after index i and their count also. To do that, I needed to maintain a set.
133677385

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

Why a lot of solves for D div2 -__- ?

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

Why do I think $$$O(n\sqrt n\log n)$$$ can pass 1e5 in 4s?

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

    It can pass. But set runs too slow that I have to replace it with array+sort :(

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

    Actually $$$ \log n $$$ is unnecessary

    We Only need $$$ O( n \sqrt{n}) $$$ (Assume $$$n = \max a_i$$$)

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

      Lol now I feel dumb... I used a seg tree to query on $$$O(\sqrt{n})$$$ different intervals, of course I didn't realize they will all go to the same state in the next step so there are at most $$$O(\sqrt{n})$$$ different states at any step lmao.

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5 weeks ago, # |
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Good Contest , I misread D to be find number of n from 1 to 2e18 which satisfy that condition , in the last 20 mins after looking at number of submissions I read it again , felt horrible and then mind stopped working . Anyways good contest man .

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

How to solve C?

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    5 weeks ago, # ^ |
      Vote: I like it -15 Vote: I do not like it

    Let me know if you find out about approach for C. Managed to solve div2 D but couldn't solve C :(

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

      you can iterate over array and count number of items that mod(i+1)!=0
      moreover at each step you should include items that mod(i+1-1..current_count)!=0
      if at some step you found items that mod(i+1-1..current_count)==0 then answer is NO otherwise YES

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

    the problem is saying check if at least one number from 2 to i+1 isnt a divisor of a[i]. Its enough to check from 2 to min(i+1, 40) cuz lcm of 1...40(or so) is too big for a[i] to fit

    This is so because for the current number, if any number before it cannot be removed, ans is No. Else, you can remove some numbers and check if current number is divisible by i+1-count of previous numbers removed which results in the range 2 to i+1(notice removing numbers after current one does not affect the position so its pointless for current number)

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5 weeks ago, # |
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The problems were very interesting. I felt dumb after getting the idea of every solution I could xD

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5 weeks ago, # |
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Can someone tell me what I did wrong in C: If there exists no element a[i] which is a product of all the numbers (i+1)*(i)*(i-1)...2, then we should output YES. Is this correct?

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

    I think it should be least common multiple, i.e, it shouldn't be 2 * 3 * 4 == 24. It should be the LCM of 2, 3, 4 which is 12.

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    5 weeks ago, # ^ |
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    you should check lcm not product.

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

    almost...

    Your method would check for 24 in the third element when 12, 36, 48, etc. would also get a 'NO'.

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5 weeks ago, # |
  Vote: I like it +76 Vote: I do not like it

$$$q$$$-binomial? Are you serious?

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    5 weeks ago, # ^ |
      Vote: I like it -28 Vote: I do not like it

    Sadly we didn't know about this. But it's true that we were afraid that some chinse guy would use some weird stuff to solve the problem. I hope you liked the other problems.

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

I got the idea of Div2D 10 minutes after the contest. I hate my life

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

How to solve div2 C? Managed to solve div2 D but blundered in C :|

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5 weeks ago, # |
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D is jocker?

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

Nice contest. But lots of maths (:

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5 weeks ago, # |
Rev. 3   Vote: I like it +18 Vote: I do not like it

Didn't really like Div2 D. It's a very simple solution, and either you find it very quickly or you sit around thinking for a long time before you realize it and bang your head

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

    Yea, too me a whole lot of time. At the end it was a simple pattern lol. Did bruteforce and found the pattern.

    if(x==y)cout<<x<<"\n";
    else if(x>=y)cout<<x+y<<"\n";
    else cout<< y-(y%x)/2<<"\n";
    
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5 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

How to solve D ?

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

    Did bruteforce and found the pattern.

    if(x==y)cout<<x<<"\n";
    else if(x>=y)cout<<x+y<<"\n";
    else cout<< y-(y%x)/2<<"\n";
    
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    5 weeks ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    i think:

    if(x==y) ans=x if(x>y) ans=x+y if(x<y) ans=y-(y%x)/2

    although i couldn't submit in time..

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

    input x, y

    if x == y => print x

    if (x > y) print x + y

    if (x < y) print (y — (((x+y) div 2) mod x))

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

    if y < x then u can choose any n larger the y so that n % x = y holds

    otherwise if y >= x and suppose y % x = z, then if you find the highest multiple of x which is smaller then y and add z/2 to it, n will become evenly match for both numbers meaning n % x will equal to y % n.

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    5 weeks ago, # ^ |
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    Thank u

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5 weeks ago, # |
  Vote: I like it +15 Vote: I do not like it

I think this time orzdevinwang will become LGM finally!

And is he the youngest LGM in codeforces?

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

Can someone give some hints to div1 E . I only have a naive $$$O(n^6)$$$ solution .

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

    I have the O(n**6) solution but only traversing states which are reachable from the beginning and from which the end is reachable, and apparently it's fast enough. Although I guess it depends on which exact states your solution has.

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

      My solution:

      First assume that the sequence is nondecreasing . Then enumerate the first number and do a dp , which record the prefix sum and the last number .

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

        In my case the difference is that after fixing the first number I put numbers from big to small, and therefore my state is what is the maximum allowed number, how many numbers we still need to put, and what is their maximum allowed sum.

        So I guess having "maximum allowed sum" when going from big to small has fewer reachable states that having "sum" when going from small to big.

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

      My states are choosing $$$i$$$ numbers between $$$[l,r]$$$ and the smallest number is $$$l$$$, the sum of the numbers is $$$s$$$.

      How could I improve?

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

Why is the time limit in D so tight??

I have a solution that runs in around 3.4s locally, and is $$$\mathcal{O}(n \log^3 n)$$$ except for a $$$\mathcal{O}(n \sqrt n)$$$ part that takes just 0.5s. I'm sure I could make this pass if I optimised my segment tree more, but the problem shouldn't require that!

EDIT: optimised the segment tree to this special case, and now it passes (133687383). Here's a submission with my usual segment tree code (133688464).

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5 weeks ago, # |
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Is it possible to do problem C in n^2.

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5 weeks ago, # |
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Dear YouKn0wWho Your contets are very difficult for me T_T

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    5 weeks ago, # ^ |
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    That's what contests are for, practising and competing and having some fun. Solve some difficult problems rather than solving 200 problems of 800 difficulty.

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5 weeks ago, # |
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What approaches were supposed to fit into TL and ML in Div1C by the author, and which were not supposed?

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5 weeks ago, # |
  Vote: I like it +47 Vote: I do not like it
Yes Math is totally 100% Competitive Programming
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    5 weeks ago, # ^ |
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    lol. The final pattern was a simple 3 line code.

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    5 weeks ago, # ^ |
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    Lol, I think my Div 2D code amassed to a couple of lines (really only 3 "important" lines of code). Out of curiosity, did the code work?

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5 weeks ago, # |
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long long n=55; int m=20; if(m>n){ //code } Is it valid to use comparison operator between long long and int data type?

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    5 weeks ago, # ^ |
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    it will first convert int to long long before comparison, so, yes

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5 weeks ago, # |
  Vote: I like it +106 Vote: I do not like it

Here is some feedback on the problems:

  • A. Di-visible Confusion: Easy problem, ok.
  • B. Moderate Modular Mode: In general I don't like problems where there is 0 computer science involved, though I must admit that the statement of this one is nice. Moreover, the solution is very clean. Cool problem.
  • C. Extreme Extension: The statement is clean and interesting, but the "greedy" part is easy and the "only few states n/k" is standard. Nice statement, standard solution.
  • D. Artistic Partition: Here I have mixed feelings. The statement is absolutely "who cares". The fact that one may assume $$$k\le 20$$$ is cute. Computing the number of coprime pairs is very standard but always annoying for me. My solution is a DP with all the $$$n\cdot k$$$ states, which is optimized via the divide and conquer technique (likely different from the official solution). It was nontrivial to implement and I enjoyed thinking about how to optimize stuff so that it could get AC. Finally, submitting one minute before the end, I felt the adrenaline rush, which is priceless.

Overall, the contest was very well-prepared and it gave me some strong emotions, so thanks to the authors. The difficulty distribution was perfect. I am eager to read the editorial to find out how to solve D properly.

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

    Can you elaborate on the time complexity of your D? Editorial also mentions D&C and states that its actually $$$O(n \log^2 n)$$$, which I'm a bit concerned about (more like $$$O(n \log n \sqrt n)$$$).

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      5 weeks ago, # ^ |
        Vote: I like it +15 Vote: I do not like it

      The cost of an interval $$$[l, r]$$$ is given by ($$$q(x)$$$ is a function we have precomputed, namely the number of coprime pairs $$$1 \le a \le b\le x$$$)

      $$$ c(l, r) := q\big(\frac rr\big) + q\big(\frac r{r-1}\big) + \cdots + q\big(\frac rl\big) .$$$

      I think that your doubt on the complexity comes from the fact that computing $$$c(l, r)$$$ may require $$$O(\sqrt{n})$$$ operations (if this is not the issue, please clarify why you think that the complexity might be $$$O(n\log n\sqrt n)$$$.

      The trick is that, with some precomputation, we can compute $$$c(l, r)$$$ in $$$O(1)$$$. We precompute, for every $$$r$$$, the values $$$c(r/k, r)$$$; this can be done in $$$O(n\sqrt n)$$$. Then, we have

      $$$ c(l, r) = (m-l)q\big(\frac rl\big) + c(m, r) , $$$

      where $$$m$$$ is the smallest number such that $$$\lfloor \frac{r}{m}\rfloor > \lfloor \frac rl \rfloor$$$ (it can be found in $$$O(1)$$$).

      Since the cost function can be computed in $$$O(1)$$$, and we are executing the D&C dp optimization $$$\log(n)$$$ times, the total complexity is $$$O(n\log^2(n))$$$ (plus $$$O(n\sqrt n)$$$ precomputation).

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

        Sorry for confusion, I didn't read the editorial, which apparently has the same solution as yours.

        You understood me correctly, the end of editorial mentions solution that uses $$$O(\sqrt n)$$$ per one query. It's now edited, stating that in practice it fits in TL but no proofs provided on the complexity (I think it's still $$$O(n \sqrt n \log n)$$$).

        Btw, I've used this technique like 2 times in recent days, but wasn't able to apply it here, what a shame...

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

in the problem Div2D, why x < y : cout<< y-(y%x)/2<<"\n" ?

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    5 weeks ago, # ^ |
      Vote: I like it -25 Vote: I do not like it

    If you bruteforce for the values of x and y, it was following a pattern.

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    5 weeks ago, # ^ |
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    Can someone prove it with math?

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      5 weeks ago, # ^ |
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      For x < y, lets take K for which, K*x < y < (K+1)*x.

      The N for this case will be , (K*x + y)/2.

      N = K*x + (y — K*x)/2

      N % x => (y — K*x)/2

      y % N will be y — N (Since 2*N > y)

      y % N => (y — K*x)/2

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

    if x < y, then suppose y % x = z, then if we find the highest multiple of x which is smaller then y and add z/2 to it.. then n % x = z/2 and y % n = z/2, cz they both are even numbers and I can find a midpoint where both numbers multiples distance is same.

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    5 weeks ago, # ^ |
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    I asked the post but objected so much, fucking

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5 weeks ago, # |
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Nothing is better than doing charity while having an interesting competition!

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5 weeks ago, # |
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too much math.go go mathforces

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5 weeks ago, # |
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Unpopular opinion: Div2 was only observation and math, no programming. Boring experience.

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

    Sure, but isn't 'observation' key to 'problem solving' which is pretty much what competitive programming is. A keen observer is usually also a shrewd problem solver.

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      5 weeks ago, # ^ |
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      No, but I expected more data structures, algorithm concepts such as binary search.

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        5 weeks ago, # ^ |
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        I solved c using ordered set. For me it was data structures problem.

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

      Implicitly, in your argument, you assume that observation means math (or that, observational problems are inherently mathematical problems). I don't think that's true. Sometimes just observations can come from realizing that one needs a certain data structure, like recognizing the application of segment within a particular context.

      I agree that observation is key to problem-solving, but I don't think this justifies having such a mathematically heavy contest.

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

Does the writer have fetish with XOR? Why so many XOR problems from the same writers?

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    5 weeks ago, # ^ |
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    Have you tried codechef. He writes a lot of codechef contests and mostly problems is from maths and mostly xor xD.

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Can someone explain why this code gets WA? I literally did the same thing as explained in the editorial Link: Your text to link here...

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

    You don't read the complete input before printing the output for a test case. Then when you'd try to read the next test, you'd first receive the input left from the previous one.

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

      Yeah I realized that in the meantime. Stupid of me, what can I say. Thanks for explaining anyway!

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    5 weeks ago, # ^ |
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    You don't need to check for all the n elements, just for the first 21 elements.

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5 weeks ago, # |
Rev. 2   Vote: I like it -33 Vote: I do not like it

.

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    5 weeks ago, # ^ |
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    I just went ahead and downvoted you for saying that. Thank you

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5 weeks ago, # |
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what an amazing round it was. I solved C for the first time in div 2

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5 weeks ago, # |
Rev. 3   Vote: I like it -11 Vote: I do not like it

The problem D was hilarious

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5 weeks ago, # |
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Just solved Div2 D just 8 sec before the Contest Ends, Love my Life and codeforces

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5 weeks ago, # |
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It was a math contest, didn't even need computer.

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5 weeks ago, # |
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There were so many $$$69$$$'s. YouKn0wWho surely loves $$$69$$$.

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5 weeks ago, # |
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I want to know the name of the man who ranked 2 during the contest and suddently dissappear after system test .-.

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5 weeks ago, # |
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Great problems! I think Div2D was much easier than usual Div2D.

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

anyone calculated the final donation amount?

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

My personal feeling — E is much, much easier than D. For me E is a pretty standard task like "you have an obvious DP with huge complexity, optimize it with some observations and harmonic series principle". D's idea is obvious to me too, but implementation and some specific details make it harder for me.

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5 weeks ago, # |
  Vote: I like it +202 Vote: I do not like it

Despite my feelings of losing rating and my contribution throne, the problems div1ABC are pretty nice. If I have a suggestion for improvement, it's to have more topic balance. I thought there is too much number theory. (As much as integer division and remainder can be called number theory)

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

Great contest I enjoyed solving the questions and also happy for donating.

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

Silly thing happened to me today, I forgot to save file after removing cerr line and submitted the unsaved file. It passed pretests but TLEd on actual tests. Is there any way to use fast output with cerr?

meme

P.S. use clog instead of cerr

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

The contest was good, though i think it was a bit mathematically. thanks the writers

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

I got messages that my code matches solutions submitted by other people. I want to ensure that my solution were completely mine and not copied anywhere else.

I was using a public platform ideone.com to write and run my code. May be people got access to my code from there, as now i see there is a link for recent code on their platform. I will keep this in mind, not use their public version for coding my solutions.

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5 weeks ago, # |
  Vote: I like it +46 Vote: I do not like it

Does anyone know why Itst_boyfriend was removed from the contest?

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

When will ratings update?

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

Can any one make me clear how the O(N²) solution is getting ac in div 2 question C???

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

    Brute force works here because it is not really O(n^2), because actually most numbers can be removed in most positions. So a linear search for such a position does not take n steps but at most aprox 20, and on average about two or three. submission

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

This guy never disappoints. ❤

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

I mistake

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

There are a lot of math problems in this game. I like it very much

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

you know it's a bad contest when problem D has O(1) solution

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

Dear programmers, can you help me? Recently, for fun, I created a team of friends at Codeforces. After the contest, Codeforces sent me an email saying that my solutions are very similar to the solutions of alex_2008, which is in our team. The fact is that I am also alex_2008. And there in the letter it was said that for repeated violations of the rules, they would block my account. Can you tell me what to do?

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5 weeks ago, # |
Rev. 2   Vote: I like it +10 Vote: I do not like it

I participated in the round yesterday. I received a mail after the contest that my solution for DiV2 Problem B coincided significantly with two more solutions(My solution -world_classic/133631831 133631831 others solution-keetzo/133671951 133671951 , kaypee284/133672077 133672077) . As the question had a straightforward solution and the other users coincidently may have the same templates as mine so it may have coincided by chance. I request MikeMirzayanov and the team to look into the matter...

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

Congratulations for being the top contributor

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

I am amazed at how accurate your estimation is!!

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

I regret for not noticing the contest time. But nice problemset, enjoyed upsolving div2 {a-d}!

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

can somebody check my code for problem c https://codeforces.com/contest/1604/submission/133665091 it is giving wa in pretest 2 in 9422th token i think this is right can somebody plz tell where its wrong i used factorial instead of lcm

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

It have been a great round. thank you to the organizers. I look forward to such rounds from you!

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

As a tester, hope you got nice rating

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

Great Initiative ❤❤❤

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

This is amazing that we can help poor and needy by just solving problems. You are kind hearted person really. Nice!! : )