YouKn0wWho's blog

By YouKn0wWho, 22 months ago, In English

কি অবস্থা মামা? (That's Bengali for "What's up dude?")

I am super excited to invite you to participate in Codeforces Round 735 (Div. 2) which will be held on Jul/29/2021 17:35 (Moscow time). This round is rated for future LGM participants whose current rating is $$$\le 2099$$$.

You will be given $$$5$$$ problems and $$$2$$$ hours to solve them. All the problems are authored and prepared by me.

I would like to thank -

The statements are super short and I have tried to make the pretests strong. I encourage you to read all the problems and solve them all.

I would like to dedicate this contest to the fallen king, my father, who died two months ago. May he and all the departed good souls rest in peace.

Scoring distribution: $$$750 - 1250 - 1750 - 2000 - 3000$$$.

Good Luck!

UPD1: Thanks for participating, I hope that you guys loved the problems, and sorry for B being a bit difficult than usual.

UPD2: Editorial

UPD3: Congratulations to the winners.

Div.1 + Div.2:

  1. turmax
  2. Karry5307_AK_NOI2023
  3. SSRS_
  4. Pyqe
  5. X_qaeq

Div.2:

  1. Karry5307_AK_NOI2023
  2. X_qaeq
  3. the_tool_er
  4. sbren_sbeve
  5. Rednusa

Also, congratulations to the first solvers:

A: LiM_256, at $$$0$$$ mins!
B: RinShima, at $$$4$$$ mins!
C: xiaofan7, at $$$7$$$ mins!
D: 6945930042DucLA, at $$$7$$$ mins!
E: rainboy, at $$$23$$$ mins!

  • Vote: I like it
  • +2167
  • Vote: I do not like it

| Write comment?
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22 months ago, # |
  Vote: I like it +29 Vote: I do not like it

whoa!

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22 months ago, # |
Rev. 2   Vote: I like it +183 Vote: I do not like it

A Bangladeshi round after $$$7$$$ years. As a Bangladeshi , it feels very special. Eagerly waiting for it. <3

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22 months ago, # |
  Vote: I like it -91 Vote: I do not like it

Speed forces it is.

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22 months ago, # |
  Vote: I like it +14 Vote: I do not like it

We are also super excited to participate!!

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22 months ago, # |
  Vote: I like it +400 Vote: I do not like it

The problems are super interesting. As a tester, I encourage everyone to participate (and also upvote this comment :3).

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    22 months ago, # ^ |
      Vote: I like it -30 Vote: I do not like it

    your wife is really beautiful in your dp

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    22 months ago, # ^ |
      Vote: I like it +14 Vote: I do not like it

    A lot of upvotes and testers are highly recommending it... I think everyone should give it. I will also give... :)

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22 months ago, # |
  Vote: I like it +162 Vote: I do not like it

The problems statements are very clear and precise. Hope everyone will enjoy the round. And also, don't forget to READ ALL PROBLEMS.

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22 months ago, # |
  Vote: I like it +6 Vote: I do not like it

Eagerly waiting for this round

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22 months ago, # |
  Vote: I like it +146 Vote: I do not like it
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22 months ago, # |
  Vote: I like it +23 Vote: I do not like it

Eagerly Waiting for this round ! খেলা হবে মামা !

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22 months ago, # |
  Vote: I like it -27 Vote: I do not like it

Pls no fst pls no fst plsssss

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

    I almost fst is related to getting wrong answer but please tell the full form of fst.

    PS: I DON'T SPEND MUCH TIME IN CODEFORCES COMMENT SECTIONS

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22 months ago, # |
Rev. 2   Vote: I like it +35 Vote: I do not like it

Thanks for this delightful invitation, and for sharing with us the kind dedication to your father's soul.

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22 months ago, # |
  Vote: I like it +49 Vote: I do not like it

RIP. He's looking at you from heaven :)

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22 months ago, # |
  Vote: I like it +1 Vote: I do not like it

oh hoo!! The first bengali round I have seen so far. Feeling very proud.

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    22 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    A Bengali round with Bengali problems ... (expected) :)

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22 months ago, # |
  Vote: I like it +10 Vote: I do not like it

Shei

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22 months ago, # |
Rev. 11   Vote: I like it +14 Vote: I do not like it

May Allah rest your father's soul, Ameen.

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    »
    22 months ago, # ^ |
      Vote: I like it -36 Vote: I do not like it

    Is it usual that i just edited my message once and it repeated 10 times ?

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22 months ago, # |
Rev. 2   Vote: I like it +128 Vote: I do not like it

As a tester, I really liked the round. The problems are very nice (Do give a read to all of them). The statements are short and concise.

Also... as a tester, it is my duty to inform you there's an upvote button to this comment... UwU

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22 months ago, # |
  Vote: I like it +93 Vote: I do not like it

as a tester, I recommend this contest to everyone.

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

অস্থির (amazing)

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22 months ago, # |
  Vote: I like it +31 Vote: I do not like it

As a Bengalee,I am very glad to see the starting line of the blog is written in Bengali.Hoping for some exciting problems.

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22 months ago, # |
  Vote: I like it +7 Vote: I do not like it

I am going to participate in this contest(& lose some rating!).

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

May Allah grant your father Jannatul Ferdous.Ameen.

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22 months ago, # |
  Vote: I like it +4 Vote: I do not like it

Super Excited!

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22 months ago, # |
  Vote: I like it +3 Vote: I do not like it

Pro A : 250 and Pro A : 750 :V

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Nice to see a Bangladeshi Round

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

Time to upsolve this and this round

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22 months ago, # |
  Vote: I like it +17 Vote: I do not like it

I see what you did to Anton :)

Spoiler
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    22 months ago, # ^ |
      Vote: I like it +31 Vote: I do not like it

    I was wondering why people are talking so much about that line. Now I realize it's in white font and I'm in dark mode, so it appeared normal text to me.

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22 months ago, # |
  Vote: I like it +34 Vote: I do not like it

This round is rated for future LGM participants whose current rating is ≤ 2099

Wow that was very motivating!

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

Proud of you. Best wishes for you. I am Eagerly waiting for this round. Hopefully i will enjoy the problem set. (আসো খেলবো,খেলা হব্বে ২৯ তারিখ)

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22 months ago, # |
  Vote: I like it +7 Vote: I do not like it

The statements are super short

Already feeling like it's gonna be a great round.

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22 months ago, # |
  Vote: I like it +3 Vote: I do not like it

One of the sweetest invitation ✨✨✨

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22 months ago, # |
  Vote: I like it +95 Vote: I do not like it

As a Codeforces Optimal Theme user I see this!

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    22 months ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    We can also drag it to see the rest

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      22 months ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      look It says "antontrygubO_o for accepting all of my problems at gunpoint".

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

Hope that Bangladeshi round will be held more often beginning with this round.

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22 months ago, # |
Rev. 2   Vote: I like it +1 Vote: I do not like it

I am seeing "কি অবস্থা মামা" in a Codeforces blog!! What a pleasure for eyes!! Not going to miss this contest at any cost.

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22 months ago, # |
  Vote: I like it +12 Vote: I do not like it

pari na pari ,khela hobe !

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

5 problems & 2 hours is the best format for a CF round. I don't know why this is so rare nowadays. Hope this will be a great round. Best of luck.

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22 months ago, # |
  Vote: I like it +1 Vote: I do not like it

As a Bangladeshi this is a very mesmerizing news. This will surely encourage Bangladeshi contestant to be more precise on this competitive filed. Proud to be a Bangladeshi. Congratulations to you all and we are very honored. Wising best of luck to everyone. Hopefully this will be an interesting contest. Waiting to be a part of this historical journey..

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22 months ago, # |
  Vote: I like it +3 Vote: I do not like it
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22 months ago, # |
  Vote: I like it +20 Vote: I do not like it

Love from Kolkata(India) <3

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22 months ago, # |
  Vote: I like it +15 Vote: I do not like it

Kya hal h bhai ke (that's in hindi for what's up dude)

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22 months ago, # |
  Vote: I like it +15 Vote: I do not like it

I would like to dedicate this contest to the fallen king, my father, who died two months ago.

Sorry to hear about this. May his Soul Rest In Peace.

Thanx For the Round BTW

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Very excited to participate this round!

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22 months ago, # |
  Vote: I like it +10 Vote: I do not like it

Omg! Bangla Brigade on fire, so many comments within 2hrs!!
As a YouKn0wWho Fan I highly recommend participating in this round, he has authored many lovely problems on CodeChef and toph.co before. Super excited for this round!

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

Let's hope problems are as interesting as this announcement was.

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22 months ago, # |
Rev. 5   Vote: I like it -18 Vote: I do not like it

a great contest for us. thanks

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22 months ago, # |
  Vote: I like it +141 Vote: I do not like it

When author says "I encourage you to read all the problems"

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    22 months ago, # ^ |
      Vote: I like it +60 Vote: I do not like it

    I managed to solve the last problem in Codeforces Round #714 (Div. 2), though I was a Pupils at the time!

    Spoiler

    So everyone should read all the problems and try to the last moment!

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      »
      »
      22 months ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      Did you have a hacky solution or just random thing which passed pretests or was it actually something close to the editorial's solution?

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        »
        22 months ago, # ^ |
          Vote: I like it +25 Vote: I do not like it

        It's a lame solution. It only checks $$$10^8$$$ pairs, and that's enough for random tests but it can be easily hacked.

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    22 months ago, # ^ |
      Vote: I like it +2 Vote: I do not like it

    That applies to specialist like me also.

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      22 months ago, # ^ |
        Vote: I like it +17 Vote: I do not like it

      That applies to a pleb CM like me also lol. Let's be real, if you can solve div 2E consistently, then you are at least master level.

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        »
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        »
        22 months ago, # ^ |
          Vote: I like it +2 Vote: I do not like it

        Agreed (esp. with the "at least" prepended to master). I still can't solve div 2E consistently

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22 months ago, # |
  Vote: I like it +54 Vote: I do not like it
lighthearted meme
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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

It's Bengali! I am so excited!!

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

YouKn0wWho

orz
  • »
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    22 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    How did you change your text color?

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

      like this probably:

      $$$\color{white}{\text{like this}}$$$

      put this : \color{white}{\text{like this}} inside of $$

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Thankyou for the contest YouKn0wWho.Very much excited for it.

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22 months ago, # |
  Vote: I like it +3 Vote: I do not like it

Okay does other contest blogs have hidden texts too? I discovered this for the first time;_;

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22 months ago, # |
  Vote: I like it +3 Vote: I do not like it

This is really impressive! Eagerly waiting to participate and get mara :3

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22 months ago, # |
  Vote: I like it +4 Vote: I do not like it

Hopefully , going to be a exciting round . And my deep condolences to you and your family .May your father's departed soul rest in Peace.

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22 months ago, # |
  Vote: I like it -10 Vote: I do not like it

Never seen A problem with 750 points, its gonna be crazy ride.

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

May ALLAH Grant Your Father Jannatul Firdaus, Brother. and I am having a great feeling that the problems will be very interesting.

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22 months ago, # |
  Vote: I like it +23 Vote: I do not like it

Yes your father is a real king, rest in peace.

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22 months ago, # |
  Vote: I like it +1 Vote: I do not like it

Wish to participate in your next round.

Best of Luck for the ICPC YouKn0wWho .

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

hi um new here:)

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Eagerly waiting ... hope to regain my lost position in this round (T~T)

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

mama?

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    22 months ago, # ^ |
      Vote: I like it +10 Vote: I do not like it

    Real meaning of mama is maternal uncle. But people of Bangladesh love to address friends, any unknown person as mama. This is a common thing in Bangladesh.

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22 months ago, # |
  Vote: I like it +14 Vote: I do not like it

This is really a proud moment vai.Waiting for it!

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

More power to you!!

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

Being excited, motivated, happy, and sad at the same blog

I'm sure your father is proud of you

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22 months ago, # |
  Vote: I like it +2 Vote: I do not like it

God bless your father

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

"The statements are super short and I have tried to make the pretests strong."

Orz

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

The score distribution seems to be quite difficult than usual.

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

I like short question descriptions very much

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22 months ago, # |
  Vote: I like it +18 Vote: I do not like it

This round is rated for future LGM participants whose current rating is $$$\le$$$ 2099.

What a wonderful line to read before the contest.

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22 months ago, # |
  Vote: I like it +1 Vote: I do not like it

Excelsior to take part and face new challenge adn learn from them, hope you have not added any question from xor

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22 months ago, # |
  Vote: I like it +17 Vote: I do not like it

My 100th Round in Codeforces is going to be a Bangladeshi round,really!!! As a Bangladeshi i am really excited!

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22 months ago, # |
Rev. 2   Vote: I like it 0 Vote: I do not like it

As a fan of Hero Alom, I can't wait for this round. I love Bangladesh.

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

Really proud of you, man! YouKn0wWho ❤️

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22 months ago, # |
  Vote: I like it +1 Vote: I do not like it

Trying selecting the first line under "I would like to thank -". Hahahaha

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22 months ago, # |
  Vote: I like it +1 Vote: I do not like it

He is legend in codeforce i try to follow him..i solved acroding to his 1st submission!congrats mann!

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22 months ago, # |
  Vote: I like it +1 Vote: I do not like it

Expect! First time to participate Bangladesh round :)

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22 months ago, # |
  Vote: I like it +1 Vote: I do not like it

You are proud son of your parents. RIP to his soul

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22 months ago, # |
  Vote: I like it +2 Vote: I do not like it

Bangladeshi round => Comment section fully immigrated.

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22 months ago, # |
  Vote: I like it +2 Vote: I do not like it

RIP for your father. His thoughts and blessings will be always with you.

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

I love the way you bring this contest to us. Stay strong and good luck everyone!

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22 months ago, # |
  Vote: I like it +6 Vote: I do not like it

As a tester, I recommend you to read all of the problems

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22 months ago, # |
  Vote: I like it +4 Vote: I do not like it

God bless your father

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

I don't think I'll ever manage to reach LGM. Will this contest still be rated for me?

Jokes aside, really excited for what I think is the first contest with the standard 5 problems in 2 hours format in a while!

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22 months ago, # |
  Vote: I like it +7 Vote: I do not like it

It seems that problems will be interesting. Mercy and forgiveness for your father.

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22 months ago, # |
  Vote: I like it +29 Vote: I do not like it

Bengalis, assemble.... খেলা হবে । সবাই খেলবো ।

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

Let's go amigos.

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22 months ago, # |
  Vote: I like it +25 Vote: I do not like it

"The statements are super short and I have tried to make the pretests strong." After this line, there is no doubt that the round will be marvelous.

Also, this round is being felt vary native to me. As a Bangladeshi, I seriously feeling proud.

As my father also died 4 years ago, I can understand your feelings. May Allah give Jannah to your father.

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22 months ago, # |
  Vote: I like it +2 Vote: I do not like it

love Bangladesh from Iran

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22 months ago, # |
  Vote: I like it +10 Vote: I do not like it

Voldemort's contest it's gonna be tough

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22 months ago, # |
  Vote: I like it +2 Vote: I do not like it

Short problem statements! I am expecting maths problems.

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22 months ago, # |
  Vote: I like it +10 Vote: I do not like it

Thanks for keeping the statements short! :D

Eagerly waiting like everyone! :) Hopefully It's gonna be a nice contest!

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22 months ago, # |
  Vote: I like it +1 Vote: I do not like it

Lets make it to 2000+ upvotes

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22 months ago, # |
  Vote: I like it +3 Vote: I do not like it

May he and all the departed good souls rest in peace.

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

iakioi

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Anybody noticed this on the first line in Thanks section

antontrygubO_o for his awe-inspiring coordination of the round and rejecting my problems, and thus hurting my feelings.__****

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

    Yeah, everyone did. Stop writing comments about it.

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22 months ago, # |
Rev. 3   Vote: I like it 0 Vote: I do not like it

Most people like: go to comments to watch testers comments and understand if the round will be difficult or not. Wish you will grow your rating (my eng is bad, I know)

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

Good luck, Guys!

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22 months ago, # |
  Vote: I like it +3 Vote: I do not like it

Well, this contest is probably rated for me because I'm a future Legendary Grandma.

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22 months ago, # |
  Vote: I like it +9 Vote: I do not like it

I hope that I will like this contest, and not only me. I wish your father peace in the other world.

Good luck for all.

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22 months ago, # |
  Vote: I like it -7 Vote: I do not like it

finally, div1.5

(according to scoring)

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22 months ago, # |
  Vote: I like it +15 Vote: I do not like it

Will it be a mathforces ?

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

Good luck to everyone!

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22 months ago, # |
  Vote: I like it -9 Vote: I do not like it

Did anyone see the hidden text in the blog. It reads: antontrygubO_o for his awe-inspiring coordination of the round and rejecting my problems, and thus hurting my feelings.

Just select the above line :P

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22 months ago, # |
  Vote: I like it +20 Vote: I do not like it

hope that i will become expert today :)

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

Good luck, Guys!

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22 months ago, # |
Rev. 2   Vote: I like it 0 Vote: I do not like it

Good Luck!

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Hoping A, B and C questions would be easy for a noob.

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22 months ago, # |
  Vote: I like it +25 Vote: I do not like it

Oh I will not become a LGM in the future, so the contest is unrated for me!!!!!!!

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22 months ago, # |
  Vote: I like it +7 Vote: I do not like it

Try to copy al text and you will see an invisible text after "antontrygubO_o for his awe-inspiring coordination of the round" .

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22 months ago, # |
  Vote: I like it +1 Vote: I do not like it

Even though I quit CP 2 years ago. Still going to participate. Proud!

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22 months ago, # |
  Vote: I like it +7 Vote: I do not like it

A<<<B drastic rise from A to B

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22 months ago, # |
Rev. 3   Vote: I like it +32 Vote: I do not like it

Don't leave a single question easy make all of them hard. So I can finally quit! first question take 2 min rest --------- its like an appreciation token for participation. Codeforces is a platform where top 2000 people solve question rest all see the standing page after doing A question. Again div zero contest. There is no coolness in setting a hard contest , it should be a balanced one . increment in my preparation <<<<<<<<<<<<< increment in hardness. A year ago when I knew nothing i was able to solve at least two A B and C if its of graph or standard one. Now after months of practice I'm able to solve only A . A contest is of 2: 00 hr for me its of 5 minutes . Thanks codeforces for demotivating me again! For people less than 1500 its is buzzer round who solve A faster. thanks queueforces for ruining this buzzer round also.

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    22 months ago, # ^ |
      Vote: I like it +2 Vote: I do not like it

    Do not get frustrated buddy. There will be some easy rounds you can increase your rating in those rounds.

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22 months ago, # |
  Vote: I like it +7 Vote: I do not like it

Aforces

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22 months ago, # |
  Vote: I like it +3 Vote: I do not like it

HardForces IT IS!

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22 months ago, # |
  Vote: I like it +13 Vote: I do not like it

suorer baccha contest

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22 months ago, # |
  Vote: I like it +50 Vote: I do not like it

Why the problem B and C are too hard, frick this? Btw I'm saying this just bc I was not able to do problem B and C :(.

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    22 months ago, # ^ |
      Vote: I like it +4 Vote: I do not like it

    Ikr.. even I wasn't able to do them. Probably some trick / method that I've never seen before. Unlucky :(

    Nevertheless, hoping to learn some useful stuff from the editorial

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

    prob C is easy if u just generate xors for yourself, it's some weird series of number, but in some time you should be able to find pattern in it (i started this too late)

    i found out that for numbers 0-15, 16-31, 32-47 etc difference between MAX and MIN is always 16

    just look at it:

    n = 3 m = 47

    3 2 1 0 7 6 5 4 11 10 9 8 15 14 13 12 19 18 17 16 23 22 21 20 27 26 25 24 31 30 29 28 35 34 33 32 39 38 37 36 43 42 41 40 47 46 45 44

    n = 20 m = 47

    20 21 22 23 16 17 18 19 28 29 30 31 24 25 26 27 4 5 6 7 0 1 2 3 12 13 14 15 8 9 10 11 52 53 54 55 48 49 50 51 60 61 62 63 56 57 58 59

    it must have some sort of pattern

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      »
      22 months ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      I tried this for 1.5 hour straight, couldn't find pattern to conclude ans.

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

13k participant only 2k solves for B, Great demotivation.

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    22 months ago, # ^ |
      Vote: I like it +9 Vote: I do not like it

    Yep, what a round to pick to come back to CF after a 5 year pause lol

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22 months ago, # |
  Vote: I like it +34 Vote: I do not like it

and they said global round B is hard how about this B :P

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22 months ago, # |
  Vote: I like it +4 Vote: I do not like it

idk what happened, D was much easier for me than B and C, couldn't solve them yet... :/

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22 months ago, # |
  Vote: I like it +14 Vote: I do not like it

bitwiseForces

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22 months ago, # |
  Vote: I like it +21 Vote: I do not like it

sadforces

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22 months ago, # |
  Vote: I like it +1 Vote: I do not like it

Problem D is easier than B and C(Unless I FST)

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22 months ago, # |
  Vote: I like it +4 Vote: I do not like it

D > B > C

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22 months ago, # |
  Vote: I like it +33 Vote: I do not like it

How to solve E?

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    22 months ago, # ^ |
      Vote: I like it +18 Vote: I do not like it

    Only divisors of N-1 are important. Find array d[i] = number of arrays where i divides all elements (the answer is easy to find from that array). d[1] = 2^(N-1), all other d[i]'s are either 0 or 1 (proven by the following checking algorithm): start from leaves, it is uniquely determined whether that node is selected before it's 'parent' (k cannot divide both x and x+1). If it divides neither it's 0, if the check finishes it's 1.

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      22 months ago, # ^ |
        Vote: I like it +17 Vote: I do not like it

      Whaaaat? Why $$$d[1]=2^{N-1}$$$?

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        22 months ago, # ^ |
          Vote: I like it +12 Vote: I do not like it

        Ok, I understood. I read the statement incorrectly, I thought that the numbers are written in the operations' order, not in the vertices' order.

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          22 months ago, # ^ |
            Vote: I like it 0 Vote: I do not like it

          Did the same thing :/

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            22 months ago, # ^ |
              Vote: I like it +10 Vote: I do not like it

            Me too :(. I spent an hour trying to mess around with permutations and random $$$dp$$$ states after figuring out the sum of $$$a$$$ was $$$N - 1$$$.

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        22 months ago, # ^ |
          Vote: I like it -10 Vote: I do not like it

        To be honest, that was only an intuition during the contest, basically, for every edge you have options for which ending node you select first. Since it's a tree there will be no cycles, so it's a good ordering. My first idea was $$$N!$$$, but that didn't work with sample. Probably double counting something. Definitely not a proof, let's wait for editorial :)

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          22 months ago, # ^ |
            Vote: I like it +13 Vote: I do not like it

          As _Ash__ wrote below, it's simply the number of ways to orient all edges. In different ways there are different arrays, that simply follows from a mathematical induction like one you mentioned — starting from leaves and rising up.

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    22 months ago, # ^ |
      Vote: I like it +38 Vote: I do not like it

    You can transform the situation a bit like this: You have a tree, and you have to make each edge directed. The value of each node is its indegree. The problem becomes a lot more approachable now.

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22 months ago, # |
  Vote: I like it +3 Vote: I do not like it

Nice round Thanks! Was the pretended solution for B brute force from n — 200 to n ? or will it give TLE in system test?

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

Difficulty in my opinion: E > B > C > D > A, B is my nightmare, the most right thing that I do is to skip B after 40 minutes of struggling.

In problem D you just need to know one trick: A string that contains n number of "a" and n-1 number of "a" separated by others (like 'bc' or 'b') can satisfy the condition.

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22 months ago, # |
Rev. 2   Vote: I like it +1 Vote: I do not like it

Like I have wasted about an hour over B then I have come up with this solution. Link to Solution

Still, I don't know what's logic behind this solution.

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22 months ago, # |
  Vote: I like it +88 Vote: I do not like it

How to judge D...?

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    22 months ago, # ^ |
      Vote: I like it +57 Vote: I do not like it

    Just a plain suffix automata and check if every node occurs an odd number of times in $$$\mathcal{O}(n)$$$.

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22 months ago, # |
  Vote: I like it -23 Vote: I do not like it

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    22 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    I think B was too difficult.

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      22 months ago, # ^ |
        Vote: I like it -7 Vote: I do not like it

      No, easy-peasy bruteforce

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        22 months ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        Can you share your thought process on solution for B?

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          22 months ago, # ^ |
          Rev. 2   Vote: I like it +3 Vote: I do not like it

          $$$k*(a_i|a_j)$$$ is small ($$$<1.5*10^{7}$$$) relatively to $$$i*j$$$, so lets maximize $$$i*j$$$. For that check all pairs $$$(i, j)$$$, where $$$n-1000 \leq i,j \leq n$$$.

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

            1000 is overkill. I believe 200 is enough.

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              22 months ago, # ^ |
                Vote: I like it -6 Vote: I do not like it

              Doesn`t matter.

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                22 months ago, # ^ |
                  Vote: I like it 0 Vote: I do not like it

                But don't do 2000 because you will TLE on test case 51 :(

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            22 months ago, # ^ |
              Vote: I like it 0 Vote: I do not like it

            In the problem k will be k<= 100 but how can you say that (k*(ai|aj)) will be less than 1.5*10^7.

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              22 months ago, # ^ |
              Rev. 4   Vote: I like it +1 Vote: I do not like it

              $$$a_i \leq n \leq 10^{5}$$$

              $$$a_i|a_j < 2^{17} = 131072$$$

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22 months ago, # |
  Vote: I like it +6 Vote: I do not like it

nice problems with short statements!

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

I know editorial will be here soon but I can't wait how do you solve A

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

Problem statements were short and concise,but round was tough.

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

Another Ehab in town ?? Well I liked the problems though, worth brainstorming!

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22 months ago, # |
Rev. 3   Vote: I like it +7 Vote: I do not like it

BIT-forces

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22 months ago, # |
  Vote: I like it +20 Vote: I do not like it

It was very memorable round.

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22 months ago, # |
  Vote: I like it +3 Vote: I do not like it

another div1 Contest.Hahaha

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

How did you solve B ?

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    22 months ago, # ^ |
    Rev. 2   Vote: I like it +3 Vote: I do not like it

    Check all pairs from the right-most one (N, N — 1).
    As K cannot be greater than 100 and Ai || Aj will always be strictly less than 2N, a brute-force solution should work.
    The loop is to be broken when the maximum possible value for the current pair is lower than the current max value (max. possible value would be i * j — k * 0).

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      22 months ago, # ^ |
        Vote: I like it +1 Vote: I do not like it

      Thanks , I was not able to make that observation

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    22 months ago, # ^ |
    Rev. 2   Vote: I like it +3 Vote: I do not like it

    I just searched in last 1000 elements but i don't think it will pass main tests

    Edit:it did pass but barely

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      22 months ago, # ^ |
        Vote: I like it +3 Vote: I do not like it

      it will pass. Check for last 200 would also lead to the same result

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      22 months ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      1e7 operations should pass easily

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        22 months ago, # ^ |
        Rev. 4   Vote: I like it +3 Vote: I do not like it

        Well I'm searching in O(n^2) but the sum of all elements is 3e5 so it's 3e8

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22 months ago, # |
  Vote: I like it +37 Vote: I do not like it

Wow, that was a very beautiful E problem, thank you! All around the round was nice, though for me D and B should've been swapped in difficulty...

Also, codeforces is very weird with rating around 2100, it's much easier to drop to high 2000's and get a bunch of rating in div2, than to get rating in div1 with low 2100's.

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22 months ago, # |
  Vote: I like it +13 Vote: I do not like it

How does titles of tasks related to each other and tasks itself?

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

Best Output Format Ever

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22 months ago, # |
  Vote: I like it +7 Vote: I do not like it

RIP Bitwise-operator.

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22 months ago, # |
  Vote: I like it +4 Vote: I do not like it

would rather suggest to make it unrated

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22 months ago, # |
Rev. 2   Vote: I like it +6 Vote: I do not like it

I don't know why but Codeforces felt like Atcoder today!!

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22 months ago, # |
Rev. 2   Vote: I like it +14 Vote: I do not like it
B
C
D
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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

https://codeforces.com/contest/1554/submission/124184154 sorry for this stupid question, but for question A, I don't understand why it get diff ans in testing, I got the correct ans in local. (g++ 14)

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

    Long is int on Codeforces testing system. Anyway, long isn't enough to keep 1e18. Use long long instead!

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

Tasks were really good, my mind became more powerful, thank you! And accept my condolences about your father.

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22 months ago, # |
  Vote: I like it +4 Vote: I do not like it

A :)

B :|

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

what's wrong with my solution: 124171044

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

Horrible round to me, only thing I could do was blaming myself...

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22 months ago, # |
Rev. 2   Vote: I like it 0 Vote: I do not like it

Sorry for the first version. I don't want to explain what did I think that time.


The round have two problems of Bitwise-operators, and they are hard for people like me to solve. And I think so many great participants lost their ratings in this contest, so maybe we can make this contest unrated for them.

But you ask me... I think it's okay to keep this round rated. But I suggest, don't write those problems in one contest again!

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    22 months ago, # ^ |
      Vote: I like it +14 Vote: I do not like it

    What do you mean by "too many"? Did any other problem involve bitwise operators apart from C?

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

I am hoping an amazing editorial from YouKn0wWho

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Really suggest making this round unrated.

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22 months ago, # |
  Vote: I like it +3 Vote: I do not like it

sadge spent 2 hours not realizing loop variables i * j overflows :(

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22 months ago, # |
Rev. 2   Vote: I like it +24 Vote: I do not like it

This round is rated for future LGM participants whose current rating is ≤2099

But it is advised that you are already LGM before attempting ;)

Serious point: interesting problems, short statements, but this is probably too difficult for a Div 2 round.

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Wow, these were REALLY short statements

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22 months ago, # |
  Vote: I like it +15 Vote: I do not like it

A-D(hoc)Forces

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

How to prove that time complexity of B is not O(n^2) YouKn0wWho ??

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

    Lets take if you take $$$i=n, j=n-1$$$ the worst case gives you as a result $$$n(n-1)-k(a_n|a_{n-1})$$$ with $$$a_n|a_{n-1}$$$ maximized. It's easy to check that $$$a_n|a_{n-1} \leq 2n$$$ so you know that $$$n(n-1)-k(a_n|a_{n-1}) \leq n^2-n-2kn$$$

    Lets take $$$i=(n-a)$$$ and $$$j=(n-b)$$$ and take the best case= $$$a_i=0, a_j=0$$$, you get $$$(n-a)(n-b)=n^2-(a+b)n+ab$$$.

    Now the key observation is to notice that:

    $$$n^2-n-2kn>n^2-(a+b)n+ab$$$

    iff

    $$$(a+b)n-n-2kn>ab$$$

    iff

    $$$(a+b-1-2k)n>ab$$$

    which is true if $max(a,b) > 201$ so you only have to check the last $$$200$$$ elements of the array

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

Woah!!This was an amazing round,lived up to the hype.

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

Instead of solving E, I think it's quite more interesting to think about how to write the checker of D.

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    22 months ago, # ^ |
      Vote: I like it +13 Vote: I do not like it

    Suffix automaton? We just need endpos set size of each node.

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      22 months ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      Probably. I think SAM is the best way to finish the checker.

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22 months ago, # |
Rev. 2   Vote: I like it 0 Vote: I do not like it

I misread problem $$$D$$$ and before solving it, I've solved a different problem which was quite interesting, so I'll share it:

The problem is the same, but instead of $$$N$$$ beeing the size of the string, let $$$N$$$ be the sum over all occurrences of strings only consting of one character. And $$$N \leq 10^{12}$$$ seems to fit

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22 months ago, # |
  Vote: I like it +15 Vote: I do not like it

I'm curious how the system tested in D. Maybe using suffix automaton?

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22 months ago, # |
Rev. 2   Vote: I like it 0 Vote: I do not like it

In problem B, since 0 <= a[i] <= n, we have a[i] | a[j] <= 2n and k*a[i]|a[j] <= 200n. Then for big enough n, let try all pairs among last m indices (we will choose m later). We can prove that the result will be in there. The worst case for last two indices is: n(n-1)-200n (and notice that the answer is at least that number). The best case for the uncheck indices is: (n-m)(n-m-1). We need to have: n(n-1)-200n >= (n-m)(n-m-1) or n(2m-200) >= m^2+m. In the contest, I choose m=400 with n >= 800.

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22 months ago, # |
Rev. 3   Vote: I like it +20 Vote: I do not like it

Very nice problems, although I feel like the position of B and D should be swapped. I especially liked C. The statements were so short it felt like I was solving AtCoder problems. Thanks for the contest!

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22 months ago, # |
  Vote: I like it +29 Vote: I do not like it

MikeMirzayanov I submitted A at codeforces.com and I got a server error, so I went to m2.codeforces.com and I submitted it there the same exact code then codeforces.com started to pick up and my code for A actually went through despite the server error I got. now, what happened is I have the same code uploaded twice and the system skipped the first submission and judged the second one which leads to less points. my submissions:

https://codeforces.com/contest/1554/submission/124135925

https://codeforces.com/contest/1554/submission/124135472

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Anyone noticed that ,there's no Successful hacks in this round!!!

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22 months ago, # |
  Vote: I like it +39 Vote: I do not like it

Finally a great contest with very strong pretests!

May your Dad rest in peace my friend YouKn0wWho, he should be proud of you

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22 months ago, # |
Rev. 3   Vote: I like it +7 Vote: I do not like it

Problems were really good.Thanks.I personally want more contests from you YouKn0wWho

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Is anybody able to help me understand what is wrong with this hack generator? It says "Validator 'Validator.exe' returns exit code 3 [FAIL Expected EOLN (test case 1, stdin, line 3)] close" It is for problem B

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Fast Editorial! SpeedForces!

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22 months ago, # |
  Vote: I like it +2 Vote: I do not like it

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22 months ago, # |
  Vote: I like it +32 Vote: I do not like it

To not keep you waiting, the ratings are updated preliminarily. In a few hours/days, I will remove cheaters and update the ratings again!

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    22 months ago, # ^ |
      Vote: I like it +4 Vote: I do not like it

    hello Mike.. Why cheaters are not removed from the last 2 rounds??? I saw plagarised solution but still that person is rated

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

What's the point of setting problems in this manner. There should be a certain level of uniformity in the increase of the standard of problems. Can't just set a problem having a rating around 1000 and then just move to 1800-2000 rated type problems. Looks like the problem setter was just trying to show off his skills.Totally demotivating for newcomers. There should always be a balance among the distribution of problems. I urge MikeMirzayanov to not allow these kinds of people to set problems for such a highly rated platform who just want to show off their skills and nothing else. I believe that even the high-rated coders will agree with me on this point.

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    22 months ago, # ^ |
      Vote: I like it +3 Vote: I do not like it

    You know, it's hard to aproximate the difficulty of a problem with only a few testers. Nobody is trying to show off anything, other than the abillity to create problems with short statements and good pretests.

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22 months ago, # |
  Vote: I like it +6 Vote: I do not like it

Nice problemset but days like these i wish to kill myself

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Time limit are too strict for python which cost me C problem for this round.

I got tle for my python solution https://codeforces.com/contest/1554/submission/124177594

where as when submitted same logic in cpp it passes. https://codeforces.com/contest/1554/submission/124191191

Please give some extra time to python coders and please try to keep time constraint flexible for every language.

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22 months ago, # |
Rev. 3   Vote: I like it 0 Vote: I do not like it

Great Round! Problems were good and required thinking! I found problem B to be the best! (out of A B and C)

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22 months ago, # |
  Vote: I like it +10 Vote: I do not like it

SOS solution for B without taking into account the small k 124191286

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

    Very cool.

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    22 months ago, # ^ |
      Vote: I like it +3 Vote: I do not like it

    May I ask your idea?

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      22 months ago, # ^ |
      Rev. 5   Vote: I like it +2 Vote: I do not like it
      Let x = (ai | aj)
      the max x you can get is 2n because ai<=n
      So for each x(0--->2n) you should know the best i and j to maximize the answer i*j - k*x 
      So greedily you have to know the two biggest indices i and j so that ai is a submask of x and aj is a submask of x
      
      You can solve it by SOS 
      
      

      SOS's Blog

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    22 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    982ms that was close enough lucky you...

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22 months ago, # |
  Vote: I like it -81 Vote: I do not like it

It is a perfect guide how not to make contests. All problems except D are complete trash, you just look at them and instantly realize they are trash.

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    22 months ago, # ^ |
      Vote: I like it +39 Vote: I do not like it

    Why are they trash?

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      22 months ago, # ^ |
        Vote: I like it -34 Vote: I do not like it

      Because they match the typical patterns of bad problems:

      1. You are given an object, you need to find another object when some complicated condition is true.
      2. You are given an object, you need to calculate the number of ways to construct some complicated object when some condition is true.

      You, being a coordinator, must know it.

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        22 months ago, # ^ |
          Vote: I like it +61 Vote: I do not like it

        It's a pattern of good problems

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          22 months ago, # ^ |
            Vote: I like it -17 Vote: I do not like it

          No. Reread and pay attention to the word "complicated".

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        22 months ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        Most problems match those patterns, just usually implicitly. In this case, the statements were simplified so that you don't have to go through trashy stories to get to the problems. I think a majority of people prefer it that way. Problems C and E especially can be rewritten in a way that are less explicit, the author just chose to present them like this (and I prefer it that way).

        It's the solutions that matter, not the problems.

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22 months ago, # |
  Vote: I like it 0 Vote: I do not like it

How is "yaaaazaaa" a valid answer for n = 9 in problem D. Isn't substring "aaa" occurring twice in the string??

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22 months ago, # |
  Vote: I like it +24 Vote: I do not like it

Alhamdulillah!!This is the contest I have been waiting for so long!!! finally I am blue and that's also in a contest organized by a programmer from my own country. I will never forget this day!!

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22 months ago, # |
  Vote: I like it +11 Vote: I do not like it

Thank God I skipped this one.

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22 months ago, # |
Rev. 2   Vote: I like it +158 Vote: I do not like it

I got a high rank in this Round,but I still think this Round a not really good one.That is,Problem E is too easy as the final problem of a Div 2 only Round.

Besides,Problem D is too easy.I think it will not be harder than *1200.

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    22 months ago, # ^ |
      Vote: I like it +96 Vote: I do not like it

    orz,you All Kill

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    22 months ago, # ^ |
      Vote: I like it +103 Vote: I do not like it

    I totally agree.The problems D&E are much easier than the past contests.It made this contest another speedforces.

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      22 months ago, # ^ |
        Vote: I like it +28 Vote: I do not like it

      I agree

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        22 months ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        you are masters :|

        maybe, if div2 round was too easy, participate in div1?

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

          He said this Div2 is easier than the past Div2.And I think so.

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22 months ago, # |
Rev. 3   Vote: I like it +142 Vote: I do not like it

How can Karry5307_AK_NOI2023 solve C at 00:16:27 and solve D at 00:16:13?

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    22 months ago, # ^ |
      Vote: I like it +226 Vote: I do not like it

    Just because he is Karry5307

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      22 months ago, # ^ |
        Vote: I like it +214 Vote: I do not like it

      Just because he is Karry5307

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        22 months ago, # ^ |
          Vote: I like it +225 Vote: I do not like it

        Just because he is Karry5307

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          22 months ago, # ^ |
            Vote: I like it +233 Vote: I do not like it

          Just because he is Karry5307

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            22 months ago, # ^ |
              Vote: I like it +201 Vote: I do not like it

            Just because he is Karry5307

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              22 months ago, # ^ |
                Vote: I like it +182 Vote: I do not like it

              Just because he is Karry5307

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                22 months ago, # ^ |
                  Vote: I like it -153 Vote: I do not like it

                Just because he is AKSSH5307

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                  22 months ago, # ^ |
                    Vote: I like it +219 Vote: I do not like it

                  Just because he is Karry5307

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                  22 months ago, # ^ |
                    Vote: I like it +151 Vote: I do not like it

                  Just because he is Karry5307.

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                  22 months ago, # ^ |
                    Vote: I like it +170 Vote: I do not like it

                  Just because he is Karry5307.

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                  22 months ago, # ^ |
                    Vote: I like it +215 Vote: I do not like it

                  Just because he is Karry5307.

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                  22 months ago, # ^ |
                    Vote: I like it +199 Vote: I do not like it

                  Just because he is Karry5307.

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                  22 months ago, # ^ |
                    Vote: I like it +186 Vote: I do not like it

                  Just because he is Karry5307.

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                  22 months ago, # ^ |
                    Vote: I like it +139 Vote: I do not like it

                  Just because he is Karry5307.

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                  22 months ago, # ^ |
                    Vote: I like it +72 Vote: I do not like it

                  Just because he is Karry5307

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                  22 months ago, # ^ |
                    Vote: I like it +73 Vote: I do not like it

                  Just because he is Karry5307.

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