Okrut's blog

Good Bye 2020
By Okrut, 3 years ago, In English

Hello Codeforces!

We have a pleasure to invite you to Good Bye 2020, which will take place on Dec/30/2020 17:35 (Moscow time). You will have 3 hours to solve 9 problems. The round will be rated for participants of both divisions.

The problems for this round were prepared by gawry, Anadi and me.

We would like to thank everyone who made this round possible:

We hope you will enjoy the problem set! Good luck!

UPD: Score distribution: $$$500$$$ $$$-$$$ $$$750$$$ $$$-$$$ $$$1000$$$ $$$-$$$ $$$1000$$$ $$$-$$$ $$$1500$$$ $$$-$$$ $$$1750$$$ $$$-$$$ $$$2500$$$ $$$-$$$ $$$3500$$$ $$$-$$$ $$$4000$$$

UPD: Editorial

UPD: Congratulations to the winners!

  1. tourist
  2. maroonrk
  3. Benq
  4. scott_wu
  5. fivedemands
  6. Um_nik
  7. mnbvmar
  8. heno239
  9. aid
  10. ainta
Announcement of Good Bye 2020
  • Vote: I like it
  • +1604
  • Vote: I do not like it

Comments Comments (362)
| Write comment?
»
3 years ago, # |
  Vote: I like it +206 Vote: I do not like it

New year magic when ?

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +628 Vote: I do not like it

    WHEN

    → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it +310 Vote: I do not like it

      .

      → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it +18 Vote: I do not like it

        Don't be sad, It's now available in your profile, have fun :)

        → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it +43 Vote: I do not like it

      As a tester, I recommend participants to say Good Bye 2020 with full energy so that year like 2020 should never come back. :)

      → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it +2 Vote: I do not like it

        Should this be considered a hint?

        → Reply
        • »
          »
          »
          »
          »
          3 years ago, # ^ |
            Vote: I like it +6 Vote: I do not like it

          B+

          → Reply
        • »
          »
          »
          »
          »
          3 years ago, # ^ |
            Vote: I like it +5 Vote: I do not like it

          I think so. It is a hint that the problems will be impossibly hard

          → Reply
          • »
            »
            »
            »
            »
            »
            3 years ago, # ^ |
            ← Rev. 2   Vote: I like it +5 Vote: I do not like it

            Just put all your efforts today into this contest and you'll really see a beautiful 2021. Because the problems are easy!

            → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it +13 Vote: I do not like it

        In my personal experience goodbye(s) are insanely hard contests and this is goodbye f***ing 2020, which has been really a crappy year, so as a contestant i hope no less than an insanely impossible to solve contest :D.

        → Reply
        • »
          »
          »
          »
          »
          3 years ago, # ^ |
            Vote: I like it +2 Vote: I do not like it

          No, that is not true. I have said it generally and there is nothing to preassume about the difficulty of the contest. Problems are really good and interesting.

          → Reply
          • »
            »
            »
            »
            »
            »
            3 years ago, # ^ |
              Vote: I like it +16 Vote: I do not like it

            You're extremely cute, lol :D I was clearly making a joke, but thanks for the reply. This is my first contest in a while so i may suck anyways :D.

            → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      It's a mockery!!!

      → Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +15 Vote: I do not like it

    In January, after New year

    I wait magic too, i wanna change nickname

    → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it +9 Vote: I do not like it

      me too bro

      → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it +4 Vote: I do not like it

      So can I take yours then !

      → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        I don't mind

        → Reply
        • »
          »
          »
          »
          »
          3 years ago, # ^ |
            Vote: I like it +3 Vote: I do not like it

          So cool bro . It would be great . Really excited !

          → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
        ← Rev. 2   Vote: I like it 0 Vote: I do not like it

        You can't. As far as I know names stay reserved for the same person who once took them. Try searching for Raptor.L in the handle search bar to see what I mean by that.

        → Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +19 Vote: I do not like it

    → Reply
»
3 years ago, # |
  Vote: I like it +24 Vote: I do not like it

more than glad to say good bye 2020 with more than a trifle of passion

→ Reply
»
3 years ago, # |
  Vote: I like it -20 Vote: I do not like it

Will there be a interactive problem like last year?

→ Reply
»
3 years ago, # |
  Vote: I like it +52 Vote: I do not like it

I was literally waiting for this contest since 10 months :)

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +170 Vote: I do not like it

    Says someone registered 9mos ago xD

    → Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it -185 Vote: I do not like it

    I'm already waiting for Good Bye 2021

    → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it +545 Vote: I do not like it

      Mike knows 2020 is THE END. He didnt even scheduled Hello 2021.

      → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it -10 Vote: I do not like it

        Or maybe he was waiting for you to comment this comment.

        → Reply
    • »
      »
      »
      3 years ago, # ^ |
      ← Rev. 2   Vote: I like it -145 Vote: I do not like it

      Who keeps downvoting me instantly? Is that a bot or something?

      → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it +461 Vote: I do not like it

        May be a group of moralizers

        → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it +113 Vote: I do not like it

        You have demoralized a lot of people. Maybe they are taking revenge. xD

        → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it +20 Vote: I do not like it

        Very funny, maybe you should take the opportunity to change the handle

        → Reply
        • »
          »
          »
          »
          »
          3 years ago, # ^ |
            Vote: I like it -77 Vote: I do not like it

          Yes, I'm thinking about that, so that their bot can't target the new handle

          → Reply
          • »
            »
            »
            »
            »
            »
            3 years ago, # ^ |
              Vote: I like it 0 Vote: I do not like it

            LMAO, maybe MikeMirzayanov should check if the bots exist and do something

            → Reply
            • »
              »
              »
              »
              »
              »
              »
              3 years ago, # ^ |
                Vote: I like it -52 Vote: I do not like it

              Bots do exist, I know how they work. It used to be just too easy to make a new CF account, (there were no captchas).

              I know that at least one of my enemies had around 30 accounts. It's easy to make a bot to downvote someone, because there are no captchas for login, so writing a bot is not a big deal for the people here, they're all coders.

              → Reply
              • »
                »
                »
                »
                »
                »
                »
                »
                3 years ago, # ^ |
                  Vote: I like it -70 Vote: I do not like it

                Even we can create a bot to submit and solve the problems fetching submission of others post the contest and also down-vote Monogon. I am thinking of making the same kind of a script against Monogon.

                → Reply
                • »
                  »
                  »
                  »
                  »
                  »
                  »
                  »
                  »
                  3 years ago, # ^ |
                    Vote: I like it +81 Vote: I do not like it

                  You downvoted me, I did nothing.

                  You downvote Monogon, I'll take revenge!

                  → Reply
                • »
                  »
                  »
                  »
                  »
                  »
                  »
                  »
                  »
                  3 years ago, # ^ |
                  ← Rev. 2   Vote: I like it +21 Vote: I do not like it

                  This comment of yours didn't got downvoted , looks like your haters love monogon.

                  → Reply
                • »
                  »
                  »
                  »
                  »
                  »
                  »
                  »
                  »
                  3 years ago, # ^ |
                    Vote: I like it +69 Vote: I do not like it

                  No, actually my haters are indian, and a lot of them are asleep by now.

                  → Reply
                • »
                  »
                  »
                  »
                  »
                  »
                  »
                  »
                  »
                  3 years ago, # ^ |
                    Vote: I like it 0 Vote: I do not like it

                  Ok , My mistake , When I commented you didn't had any downvoted but now you have 6 (P.S.: I upvoted your comment before commenting the first comment)

                  → Reply
                • »
                  »
                  »
                  »
                  »
                  »
                  »
                  »
                  »
                  3 years ago, # ^ |
                    Vote: I like it +9 Vote: I do not like it

                  I am still waking up :) Remembered me.

                  → Reply
                • »
                  »
                  »
                  »
                  »
                  »
                  »
                  »
                  »
                  3 years ago, # ^ |
                    Vote: I like it 0 Vote: I do not like it

                  You are really cute and talented don't know what the hell kind of person can hate you. If anybody is a true coder they won't never hate a talented coder. Might be your haters are jealous of your achievement.

                  Anyways you keep up your inspirational journey. You are hell of a motivation.

                  → Reply
                • »
                  »
                  »
                  »
                  »
                  »
                  »
                  »
                  »
                  3 years ago, # ^ |
                    Vote: I like it 0 Vote: I do not like it

                  You're the only person that ever called me cute since my teenage. Thankss a lot.

                  → Reply
            • »
              »
              »
              »
              »
              »
              »
              3 years ago, # ^ |
              ← Rev. 2   Vote: I like it 0 Vote: I do not like it

              skip

              → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it -8 Vote: I do not like it

        If someone is in mood of down voting then please downvote this too. adhocers

        → Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +2 Vote: I do not like it

    I was literally waiting for 2020 to come because I wished to watch 2020 cricket match at 20:20 pm with my 2020 biscuits but unfortunately it did not happen so now I am waiting for the earth to destroy and start its counting again from 0.

    → Reply
»
3 years ago, # |
  Vote: I like it +12 Vote: I do not like it

Can't be more excited for an year to end. Thanks codeforces and all its team for being a constant part of our daily life even in such a pandemic situation.

→ Reply
»
3 years ago, # |
  Vote: I like it +5 Vote: I do not like it

I can smell the taste of rating loss :v (kidding)

→ Reply
»
3 years ago, # |
  Vote: I like it +166 Vote: I do not like it

As a tester, I would like to honor memory of Chester

If you struggle with depression, don't be afraid of reaching for help!

Have yourself a wonderful CF round!

→ Reply
  • »
    »
    3 years ago, # ^ |
    ← Rev. 2   Vote: I like it +39 Vote: I do not like it

    Just curious how it is related

    → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it -93 Vote: I do not like it

      2020 and depression

      → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
        ← Rev. 2   Vote: I like it +164 Vote: I do not like it

        it seems you have a serious antifanclub XD

        → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it +6 Vote: I do not like it

        why people are downvoating demoralizer??any reason??his streams helped me sometimes.please give respect to him.

        → Reply
        • »
          »
          »
          »
          »
          3 years ago, # ^ |
            Vote: I like it +22 Vote: I do not like it

          Some stupid haters downvote the post as soon as he writes and then as you know that the future of the comment depends on it's starts people go on downvoting it.

          → Reply
          • »
            »
            »
            »
            »
            »
            3 years ago, # ^ |
              Vote: I like it -123 Vote: I do not like it

            I just think that MikeMirzayanov is great.

            (Let's see if they have the balls to downvote this too)

            → Reply
        • »
          »
          »
          »
          »
          3 years ago, # ^ |
            Vote: I like it +169 Vote: I do not like it

          idk, it starts being slightly annoying seeing a comment by him on almost all blog posts (not judging tho)

          → Reply
          • »
            »
            »
            »
            »
            »
            3 years ago, # ^ |
              Vote: I like it -89 Vote: I do not like it

            I get downvoted on CF because I don't have a life outside it? Well ok nice makes sense

            → Reply
        • »
          »
          »
          »
          »
          3 years ago, # ^ |
            Vote: I like it +28 Vote: I do not like it

          His comments are demoralizing.

          → Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +18 Vote: I do not like it

    This is my December...

    → Reply
»
3 years ago, # |
  Vote: I like it -94 Vote: I do not like it

Rename it to FUCK OFF 2020

→ Reply
»
3 years ago, # |
  Vote: I like it +52 Vote: I do not like it

As a tester, I would say that this contest is the only good thing happening in 2020.

→ Reply
»
3 years ago, # |
  Vote: I like it -13 Vote: I do not like it

Happy NewBye 2020 !

→ Reply
»
3 years ago, # |
← Rev. 2   Vote: I like it +42 Vote: I do not like it
meme
→ Reply
»
3 years ago, # |
  Vote: I like it +11 Vote: I do not like it

Will there be in this New year a nickname changing and New year magic?

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    just one thing i want in my life right now, is "NEW YEAR MAGIC" :3 wanna change my handle badly!

    → Reply
»
3 years ago, # |
  Vote: I like it +34 Vote: I do not like it

Good bye 2020 and Happy 2020-II :))

→ Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

can i reach expert before 20201? what do you guys think?

→ Reply
»
3 years ago, # |
  Vote: I like it +12 Vote: I do not like it

one day I will also reach candidate master. AMEN

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +21 Vote: I do not like it

    "Shoot for the moon — If you miss, you'll end up in the stars."

    → Reply
»
3 years ago, # |
  Vote: I like it -8 Vote: I do not like it

SecondThread as you are one of the best coders who have experience with problems, what is your opinion about the contest?

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +36 Vote: I do not like it

    Thanks! I don't like talking about problem sets before they are released (to anyone other than the authors of course), but I would definitely recommend participating if you can!

    → Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

I am looking forward for this with huge interest!

→ Reply
»
3 years ago, # |
← Rev. 2   Vote: I like it +21 Vote: I do not like it

I love coding but I want to gather with my family at the end of the year :((

Good luck to you and have a nice New Year's Eve <3

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

Will be there also Hello 2021 contest?

→ Reply
»
3 years ago, # |
  Vote: I like it +67 Vote: I do not like it

I WISH I WOULD HAVE GIRL FRIEND IN 2021

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +95 Vote: I do not like it

    ???: Can you date with me tomorrow?

    No, I can't. I have a rated codeforces round tomorrow

    → Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +3 Vote: I do not like it

    Try following all the things mentioned in this blog

    → Reply
»
3 years ago, # |
  Vote: I like it +57 Vote: I do not like it

Some coders with the name ---"I LOVE _______" are extremly waiting for 2021...xD

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +16 Vote: I do not like it

    I_love_myself has nothing to worry about

    → Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +6 Vote: I do not like it

    I am too bro.My name is Roman.

    → Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +16 Vote: I do not like it

    I am gonna set my name to tanya_romanova_loves_me xD

    → Reply
  • »
    »
    3 years ago, # ^ |
    ← Rev. 2   Vote: I like it 0 Vote: I do not like it

    how do I change my handle name, please refer me to some blog or steps (I am asking since I think maybe we can change it at the end of a year, if I am wrong then just excuse me for asking)

    → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      I don't think you can do that.. You should have decided what you wanted as your handle beforehand. :)

      → Reply
»
3 years ago, # |
  Vote: I like it +39 Vote: I do not like it

Do KAN and Nebuchadnezzar coordinate together because they have the same name?

→ Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Hope everything will be better in 2021

→ Reply
»
3 years ago, # |
  Vote: I like it +4 Vote: I do not like it

LazyPrime ORZ

→ Reply
»
3 years ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

I think that Goodbye 2020 is the only good thing in 2020

Hope everything will be better!

→ Reply
»
3 years ago, # |
  Vote: I like it +22 Vote: I do not like it

As a tester, I found the problems very interesting and enjoyed solving them. Good luck :)

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

    Or enjoyed not able to solve them? :P

    I must say these 3hrs rounds are usually more difficult :(

    → Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Hoping MikeMirzayanov to change his username as a new year gift :)

→ Reply
»
3 years ago, # |
  Vote: I like it +50 Vote: I do not like it

I hope that the design of Legendary grandmaster will be upgraded to New Year Magic. Look at the rating digits

→ Reply
»
3 years ago, # |
  Vote: I like it -11 Vote: I do not like it

Just curious, What is the strategy to be followed to increase rating in global rounds?

→ Reply
»
3 years ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

How come rating of some coders directly start from 1500?

→ Reply
»
3 years ago, # |
  Vote: I like it +166 Vote: I do not like it

As a tester, Good Morning and Goodbye!

→ Reply
  • »
    »
    3 years ago, # ^ |
    ← Rev. 4   Vote: I like it +18 Vote: I do not like it

    Maybe "Good Bye" would look better than "Goodbye", considering the round name? [Also, hoping that you can recover from sickness very swiftly!]

    → Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

I wish This Good Bye 2020 will not become good bye expert for me.

→ Reply
»
3 years ago, # |
  Vote: I like it +1 Vote: I do not like it

What about the Score-Distribution (or penalties for wrong submission) ?

→ Reply
»
3 years ago, # |
  Vote: I like it +15 Vote: I do not like it

Can't be more excited for an year to end. Thanks codeforces and all its team for being a constant part of our daily life even in such a pandemic situation.

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +3 Vote: I do not like it

    Thank you for all your help and guidance on YouTube! : )

    → Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +5 Vote: I do not like it

    yea and thank you and all other youtubers and streamers to help understand the solution better :)

    → Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

As a tester I think you will enjoy these statements : )

→ Reply
»
3 years ago, # |
  Vote: I like it +95 Vote: I do not like it

→ Reply
»
3 years ago, # |
  Vote: I like it +23 Vote: I do not like it

Request : Dark mode/theme for codeforces in 2021

it feels better on eyes, continuously switching between text editor (which has dark theme) and codeforces Websites causes eye strain.

Just a small request to devlopers.

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    or just modify your text editor until they add it?

    → Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Is it rated?

→ Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Is this contest suitable for someone in Div. 3. I am in grade 9 and have a decent understanding of CP up until this point.

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    You can try the first three problems.

    → Reply
»
3 years ago, # |
  Vote: I like it +69 Vote: I do not like it

3 hours, 9 tasks. it looks like good training for ICPC.

Can you allow team registration?

→ Reply
»
3 years ago, # |
  Vote: I like it +1 Vote: I do not like it

31 December: Am i joke to You! (*_*)

→ Reply
»
3 years ago, # |
  Vote: I like it +5 Vote: I do not like it

My First Good Bye Contest in Codeforces!

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

The first contest I gave was Hello 2020. How soon a year passed

The main reason for my progress this year has been Codeforces

→ Reply
»
3 years ago, # |
← Rev. 2   Vote: I like it +13 Vote: I do not like it

.

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +3 Vote: I do not like it

    Anish Giri eliminated already so there is no point in watching anymore :/

    → Reply
»
3 years ago, # |
  Vote: I like it +2 Vote: I do not like it

rated for both divisions? I think we have div1, div2, div3. which two are rated?

→ Reply
»
3 years ago, # |
  Vote: I like it +3 Vote: I do not like it

pog

→ Reply
»
3 years ago, # |
  Vote: I like it +6 Vote: I do not like it

I hope this last contest won't land me back into specialist. Fingers crossed :)

→ Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Seems like this would become the contest with highest number of participants. 17k+ have already registered!

→ Reply
»
3 years ago, # |
  Vote: I like it +17 Vote: I do not like it

My rating is 2021, wondering if I should give this contest to spoil it...

→ Reply
»
3 years ago, # |
  Vote: I like it +1 Vote: I do not like it 
Your code here...
print("Hello 2021")

I think that all code editor should change their welcome style--> "Hello world"-->"Hello 2021"

→ Reply
»
3 years ago, # |
  Vote: I like it +6 Vote: I do not like it

Today's contest will help me to reach pupil. AMEN

→ Reply
»
3 years ago, # |
  Vote: I like it +31 Vote: I do not like it

GoodBye rating!

→ Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

This is the last contest of year I hope this at least goes well for me

→ Reply
»
3 years ago, # |
← Rev. 2   Vote: I like it +44 Vote: I do not like it

I really don't want to bring my orange name to 2021 . This is my last chance to reach red in 2020!

→ Reply
»
3 years ago, # |
← Rev. 3   Vote: I like it -9 Vote: I do not like it

I Love Second :(

→ Reply
»
3 years ago, # |
  Vote: I like it +1 Vote: I do not like it

Nice, I have been waiting for a long time. Thanks Codeforces !!!!

→ Reply
»
3 years ago, # |
  Vote: I like it +1 Vote: I do not like it

Why not be "Hello 2021"???

→ Reply
»
3 years ago, # |
  Vote: I like it +63 Vote: I do not like it

2020 was the worst phase my life. Full of depression and suicidal thoughts. Literally I was striving to overcome. Luckily I survived and now I will be participating here in Good Bye 2020 :)

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +4 Vote: I do not like it

    Hope this contest will make you a good memorize. All the best!

    → Reply
»
3 years ago, # |
  Vote: I like it +25 Vote: I do not like it

When is the contest "Good bye COVID-19"?

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +10 Vote: I do not like it

    When covid will gone, it must be celebrated necessarily!

    → Reply
»
3 years ago, # |
  Vote: I like it +11 Vote: I do not like it

This makes me soooo happy. Finally 2020 is going :')

→ Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

I've never had a positive delta in any Div1 Div2 combined round, let's see if I'm able to get out of this curse today :P

→ Reply
»
3 years ago, # |
  Vote: I like it +4 Vote: I do not like it

Goodbye, 2020! Hope this will be a good round with strong pretest, short and clear statement problem.

→ Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Good Bye 2020 on 30th Dec: MikeMirzayanov be like I can't wait till 31st to say good bye to 2020.

→ Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

I have a feeling I'll have a positive delta in this round :-P

→ Reply
»
3 years ago, # |
  Vote: I like it +15 Vote: I do not like it

Rating Bye-Bye 2020?

→ Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Those who start 2021 year with a rating of 2021 will be lucky :P

→ Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

4 problems with scoring less than 1000, 6 less than 1750! Is it gonna be SpeedForces :\

→ Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Hoping this Good Bye 2020 doesn't turn out to be Good Bye ratings. Fingers crossed.

→ Reply
»
3 years ago, # |
← Rev. 2   Vote: I like it +2 Vote: I do not like it

One Decade on codeforces will be completed by today's conntest for tourist

→ Reply
»
3 years ago, # |
  Vote: I like it +1 Vote: I do not like it

does this distribution mean problems would be easier?

→ Reply
»
3 years ago, # |
← Rev. 2   Vote: I like it +310 Vote: I do not like it

I know the authors and I have an idea. Let's not destroy their New Year's Eve and let's assume that the statements are correct, and not ask 500 questions this round, ok? This is a combined round, we can assume that if something is wrong, then, let's say, somebody orange+ will ask a question about this. OK? If you think that something is wrong with the statement — assume that you misunderstood it.

What do you think about this idea guys? Let's treat this as a gift for them.

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    Yes

    → Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    There are already more than 1200 orange+ registered participants so I suggest that oranges like me should leave that responsibility for reds.

    → Reply
»
3 years ago, # |
  Vote: I like it +13 Vote: I do not like it

this year thaught me many things, gave me many experience, but the best thing i ever experienced was that happiness when my first solution was accepted on codeforces contest. hello every coders out here, i love you all.

→ Reply
»
3 years ago, # |
  Vote: I like it +41 Vote: I do not like it

Really enjoyed the statements! Thank you!

→ Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Something irrelevant, if I submit the correct solution twice do I get -50 as penalty for that?

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +12 Vote: I do not like it

    yes.. count the last correct submission. others as penalty.

    → Reply
»
3 years ago, # |
  Vote: I like it +72 Vote: I do not like it

Should've had one more problem between F and G :(

→ Reply
»
3 years ago, # |
← Rev. 2   Vote: I like it -15 Vote: I do not like it

Bye 2020 !!... Let's find out how will your 2021 be

click one of the options below...if u get Rick Roll ..Believe me your 2021 will be amazing

1.A

2.B

1.C

2.D

→ Reply
  • »
    »
    3 years ago, # ^ |
    ← Rev. 2   Vote: I like it +21 Vote: I do not like it

    Jokes on you, the browser usually shows the url in the bottom left corner when you hover your mouse over a link.

    → Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

How to solve E ??
I wish my knowledge like apollo or pan !

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +11 Vote: I do not like it

    Basically, you fix j and then you realise that the answer for all sums with that j is (sum of i&j) * (sum of j|k). Then you just use bitwise decomposition of the numbers to find those values quickly.

    → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      How exactly do you find the values quickly, if you could elaborate on that? I've realized the first observation and couldn't figure out the other part.

      → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        You decompose each number into its bit representation.

        Then if bit x is on in j, you add 2^x * (number of bit x on across all numbers) to the sum of i&j and n * 2^x to the sum of j|k.

        If bit x is off, you just add 2^x * (number of bit x on across all numbers) to the sum of j|k.

        → Reply
        • »
          »
          »
          »
          »
          3 years ago, # ^ |
            Vote: I like it 0 Vote: I do not like it

          I pretty much did this but got TLE. Can someone tell me why? https://codeforces.com/contest/1466/submission/102858405

          → Reply
          • »
            »
            »
            »
            »
            »
            3 years ago, # ^ |
            ← Rev. 2   Vote: I like it +3 Vote: I do not like it

            Your logic is correct but actually the time limit is strict. Check the constants that are responsible for TLE. And calling functions within functions causes too much overhead.

            I think the function calc is the reason for TLE. It is an extra loop each time which can be computed in testcases function itself without any extra loop.

            → Reply
          • »
            »
            »
            »
            »
            »
            3 years ago, # ^ |
              Vote: I like it +3 Vote: I do not like it

            slow IO. Try using ios::sync_with_stdio(false); cin.tie(0); cout.tie(0); on the begining

            → Reply
    • »
      »
      »
      3 years ago, # ^ |
      ← Rev. 2   Vote: I like it -8 Vote: I do not like it

      can you see my code and tell me where I made mistake?)

      → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      After skimming the editorial, it is clear to me how algebraically we can discover this fact (of separating the components as you did). When you solved in in contest, did you also do algebraic manipulations or is there an intuitive reason for why this is true?

      → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it +5 Vote: I do not like it

        I looked at the double sum after fixing j and realised it could be separated out into the product of two sums. It's somewhat intuitive if you have played around with a lot of summations, I guess, but I still did the algebraic proof for it.

        → Reply
  • »
    »
    3 years ago, # ^ |
    ← Rev. 2   Vote: I like it 0 Vote: I do not like it

    You should split to bits all the numbers and count bits in each position out of 60, let it be kb[i]. Fix each x[j] then you can count the sum of all (x[i]&x[j])*(x[j]|x[k]). In order to compute (x[i]&x[j]), choose all positions p where bit of x[p] in this position is 1, then (x[i]&x[j]) = sum of 2^p * kb[p] for all p. In order to compute (x[i]|x[j]), choose all positions p where bit of x[p] in this position is 1 and all over positions p1, then (x[i]&x[j]) = sum of 2^p * n + sum of 2^p1 * kb[p1]

    → Reply
»
3 years ago, # |
← Rev. 2   Vote: I like it +4 Vote: I do not like it

I'm like 50-50 on whether G is super brain observation or string algorithm, and either one is :(

Good contest though. A bit on the easy side for the first six questions, but nice problems.

→ Reply
»
3 years ago, # |
  Vote: I like it -13 Vote: I do not like it

test 7 on F

→ Reply
»
3 years ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

A good contest for me at the end of the year, solved 5, wish they pass the system testing :) Finally became specialist at the end of the year :)

→ Reply
»
3 years ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

any ideas/hint for D? i did dfs but can't recognized my bugs :/

EDIT: got AC right now, thanks guys for your insights chenreddy Liviu2000 rum3r Guslix

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    DFS not needed. Try to solve the problem by observing the optimal edge distribution for small inputs. Try to make use of indegrees.

    → Reply
  • »
    »
    3 years ago, # ^ |
    ← Rev. 2   Vote: I like it 0 Vote: I do not like it

    try to build an array of pairs {degree,weight} and then sort it.

    → Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    It's can make new subgraph of new color such way that the new subgraph is connected. New subgraph obtains from one of current subgraphes by splitting to 2 parts. Each time when k increasing by 1, the value of coloring is increasing by the value of such vertice where was splitted the old subgraph. So for each k choose maximum vertice of possible. Just count for each vertice the number of edges that adjacent this vertice

    → Reply
»
3 years ago, # |
  Vote: I like it +13 Vote: I do not like it

Cool NY contest, thanks!

→ Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

This round was sexy AF. I really enjoyed the problems (like a lot!). This has been my best performance so far and I'm very happy that I was able to do so in the last contest of the year. It's been a rough year for many, a great time to grind CP for others and a somewhat meh year for me. Whatever it has been, happy new year to everyone! Hope everyone has a great year ahead!

I don't understand how F could possible have 1000+ solves as it seems way too orz than normal. If someone could tell me how to solve, I would be very happy about it. The problems this round were great (to say the least) and the difficulty ordering and level felt perfectly balanced. Thank you authors!

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    If you think about how xor of individual dimensions cancel out on F, we can reduce it to a minimum spanning tree problem. Edges will be connecting the two dimensions that are on in a matrix (or a dimension to 0 if the matrix only has one on dimension), and weights on the edges is simply the edge number. This produces lexicographical order.

    It can be shown that all 2^|S'| possible sums produced are unique.

    → Reply
»
3 years ago, # |
  Vote: I like it +16 Vote: I do not like it

Was score decay adjusted for 3 hour duration?

→ Reply
»
3 years ago, # |
  Vote: I like it -50 Vote: I do not like it

Another shit of 2020 ended today lowering n to 10000 in C allows dp[N]*[26]*[26] solutions but memory limit exceeded due to tight constraints.

→ Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

I wish you a happy new year Hoping for your increasing success and a world without corona virus in 2021!

→ Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Why this code gives TL? https://codeforces.com/contest/1466/submission/102850721

→ Reply
»
3 years ago, # |
  Vote: I like it +1 Vote: I do not like it

How to Solve Problem C ?

→ Reply
  • »
    »
    3 years ago, # ^ |
    ← Rev. 2   Vote: I like it +3 Vote: I do not like it

    Iterate from 1 to n and if s(i,i+1) is a palindrome then replace s[i+1]. Else if s(i-1,i ,i+1) is a palindrome replace s[i+1].

    → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      Why is it always optimal to replace $$$i+1$$$ ?

      → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it +3 Vote: I do not like it

        Changing i+1 will rule out the possibility of i+1,i+2 and i+1,i+2,i+3 being a palindrome as well.

        → Reply
»
3 years ago, # |
  Vote: I like it +1 Vote: I do not like it

How to solve C, anyone?

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    You can always make a palindrome cease to exist if you change its middle character (if even length) or change 2 middle characters (odd length > 3). So we just need to find length 2 and 3 palindromes and change them so that they donot remain palindromic.

    → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      I came up with that idea, but couldn't proceed more than that. tried a way to remove greedily but was failing i.e. getting WA. Can you elaborate how to remove 2/3 len palindromes?

      → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
        ← Rev. 2   Vote: I like it 0 Vote: I do not like it

        Check if the first two characters are same, then change the second one. Now run a loop form the 3rd character to last and check if it is equal to any of the previous two characters. If it is, change it. When I say change, consider to changing it to some arbitrary character which is not a lower case alphabet. This is because, since you have 25 choices to change the character, and a character from the string can only contribute to maximum 4 different palindromes, that is, i-2, i-1, i+1, i+2. There is always an optimal choice that doesn't affect other palindromes.

        → Reply
        • »
          »
          »
          »
          »
          3 years ago, # ^ |
            Vote: I like it 0 Vote: I do not like it

          my second submission had exactly same idea, but smh it got WA and i thought that this idea is incorrect.

          → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it +1 Vote: I do not like it

        Yeah sure,

        For len 2 palindromes, say at indices : (i,i+1) you have to set the second character(i+1) such that it does not equal to i,i+2 and i+3.

        For len 3 palindromes, say at indices : (i,i+1,i+2) you have to set the third character(i+2) such that it does not match (i,i+1,i+3 and i+4).

        Also there is a condition for len-3 here : (s[i]!=s[i-1]) which is explained below :

        So we would first correct all 3 len palindromes and then proceed to filter all 2 len.

        Explanation of condition:

        Say there is some string of form "bbab". Here there is a 3 len "bab" substring. So according to our logic we would make the last b equal to some other valid character, say now it became : "bbax". Now we proceed to 2 len filter and find "bb". And now say we get "byax". So changes are 2, but answer is 1 as you can always change the second b. i.e "bxab" works here.

        Lastly we count the new changes by storing the indices in a set.

        C
        → Reply
        • »
          »
          »
          »
          »
          3 years ago, # ^ |
            Vote: I like it 0 Vote: I do not like it

          thanks for the detailed explanation. got it. i did smthg similiar, will try to figure out what went wrong.

          → Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    approach each adjaent 3 characters must be different. think of greedy/dp now

    → Reply
»
3 years ago, # |
  Vote: I like it +6 Vote: I do not like it

Because of question E, I learnt how to write and submit C++ code today. I have always been writing in Python.

It is a good start for 2021.

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +9 Vote: I do not like it

    Because of question E, I learnt to be careful with mods

    → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      me too

      → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it +2 Vote: I do not like it

        I wish I found the bug quickly.

        → Reply
        • »
          »
          »
          »
          »
          3 years ago, # ^ |
            Vote: I like it +3 Vote: I do not like it

          Can't believe I didn't find the overflow in n*xs[i]%MOD until after the contest. I spent more than 20 minutes double-checking everything except this.

          → Reply
          • »
            »
            »
            »
            »
            »
            3 years ago, # ^ |
              Vote: I like it 0 Vote: I do not like it

            Funny thing is I wrote debugging bruteforce and those random inputs couldn't get the bug. Then I accidentally fixed manually

            → Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +4 Vote: I do not like it

    How to solve Problem E ?

    → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it +3 Vote: I do not like it

      Think in terms of bits. Make a 2D array of n times 60. Here 60 represents the maximum number of bits required to represent any given number in binary

      → Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +3 Vote: I do not like it

    forget about python, my $$$O(N * log(1e18) * log(60))$$$ code in C++ gave TLE and i have to remove $$$log(60)$$$ factor to make it work. Still not sure if it will pass the system-tests or not..

    → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      I changed a%2 == 1 to a&1 to check for parity and it improved my code from TLE for test 3 to passing pretest near time limit.

      I should also have used a = a >> 1 instead a = a/2.

      → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        I should also have used a = a >> 1 instead a = a/2.

        well compiler optimization does that for us in C++ afaik, i am not sure how it improved by using bitwise operators.

        → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        Why not use C++ for submission then. Your solution barely passed. It can get FST

        → Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +5 Vote: I do not like it

    Same. It appears not a single Python / Pypy submission passed the pretests. I wasted 2 penalty attempts on that, and then the time it took me to translate my code from Python into C++. I agree, great skills to have — clearly the majority use C++ for a reason. Frustrating for the in-contest implications, though!

    → Reply
    • »
      »
      »
      3 years ago, # ^ |
      ← Rev. 2   Vote: I like it 0 Vote: I do not like it

      I don't even know how to compile C++ on my computer. I don't even know which version of C++ to use, and what are the differences. I took someone's code from a past contest and emulated its syntax.

      I initially used ideone to run the reference code, but the code seems to be always published on default. I moved to the Codeforces custom invocation and it finally printed something sensible after 1 hour.

      → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        Well done for managing. I was a little bit ahead of you. I have done some questions in C++ before and have a compiler on my PC. I just prefer to use Python as I'm much more confident in the data structures. These problems happen more often that I'd like, though, so perhaps it is time to make the switch. A New Year's Resolution, maybe.

        → Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Problem E is Python's nightmare. Also mine.

    → Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

I tried to solve problem F in following way : First sort the input . Now we traverse from smallest to largest in lexicographic order, if i am at some string of form say 010001 , then i will check if there exist two strings previously 010000,000001 or 010x00,000x01 i.e two strings whose xor can give the that string .If there exist such strings then we can skip the current string. I didn't knew fast way of doing that . Is my approach correct and if yes how to do above fast ?

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    We essentially have to implement some improvised Gaussian elimination row by row but should not store the entire contents. I couldn't come up with a proper algorithm for this in the time given.

    → Reply
»
3 years ago, # |
← Rev. 2   Vote: I like it +20 Vote: I do not like it

I feel so sorry for you Radewoosh

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +55 Vote: I do not like it

    Don't worry, it wasn't even close to being correct, but who knows, maybe more time would be useful here.

    → Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

https://codeforces.com/contest/1466/submission/102854853 test 2 anyone?

→ Reply
»
3 years ago, # |
  Vote: I like it +3 Vote: I do not like it

can anyone share how to solve F?

→ Reply
»
3 years ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

C (with more lenient constraint): https://csacademy.com/contest/round-86/task/palindrome-free-strings/

→ Reply
»
3 years ago, # |
  Vote: I like it +11 Vote: I do not like it

Very interesting problems!Thanks to everyone who contributed!

→ Reply
»
3 years ago, # |
  Vote: I like it -78 Vote: I do not like it

I do not get why would I not get E. The math was correct I got test case 1 and then I would not pass test case 2. Please tell me what I could be possibly doing wrong.

#include<bits/stdc++.h>
#define ll long long
#define ld long double
//#define M_PI (2*acos(0))
#define MAX_N 10001
#define MOD 1000000007
#define apo(a,b) sqrtl( powl(a.x-b.x,2) + powl(a.y-b.y,2) )
#define ldeq(a,b) ( fabsl(a - b) < 0.00000000007 )
#define rep(a,b) for(int i=a; i<=b; i++)
#define repv(a,b,i) for(int i=a; i<=b; i++)
#define mmod(a,b) ( (a >= 0) ? ((a%b)%b) : ( ( ( a + ( ((abs(a)+b)/b) * b ) ) % b ) % b ) )
#define int ll
using namespace std;

int p[60];
int mp[600000+1];
int all[60];

void doit(){

	int n;
	cin>>n;

	vector < int > x;
	x.push_back(0);

	int f;
	rep(1,n){
		cin>>f;
		x.push_back(f);
	}

	n = x.size()-1;

	int ans = (int)( 0 );
	rep(0,59){
		all[i] = (int)( 0 );
	}

	rep(1,n){
		int s = 0;
		while( s < 60 ){
			if( (int)( x[i] & p[s] ) != (int)(0) ){
				all[s]++;
			}
			s++;
		}
	}

	rep(1,n){
		int tmp = 0;
		int s2 = (int)(0);
		while( s2 < 60 ){
			if( (int)( x[i] & p[s2] ) != (int)(0) ){
				tmp += ( ( n * ( p[s2] % MOD % MOD ) ) % MOD % MOD );
				tmp = (tmp % MOD % MOD);
			}
			else{
				tmp += ( ( all[s2] * ( p[s2] % MOD % MOD ) ) % MOD % MOD );
				tmp = (tmp % MOD % MOD);
			}
			s2++;
		}
		mp[i] = tmp;
	}

	rep(1,n){

		int s = (int)(0);
		while( s < 60 ){

			if( (int)( x[i] & p[s] ) != (int)(0) ){
				int ep = ( ( all[s] * p[s] ) % MOD % MOD );
				ans += ( ( ep * mp[i] ) % MOD % MOD );
				ans = ( ans % MOD % MOD ); 
			}

			s++;

		}

	}

	ans = ans % MOD % MOD;
	cout<<ans<<endl;

}

#undef int
int main(){

	ios::sync_with_stdio(false);
  	cin.tie(0);

	ll t=1;
	cin>>t;

	ll k = 1;
	for(int i=0;i<60;i++){
		p[i] = k;
		k = k * (ll)(2);
	}

	while(t--){
		doit();
	}
  	
}
→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +6 Vote: I do not like it

    You can use spoiler to hide the code . It will look better .

    → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      what spoiler man the contest was over by the time I asked the question?

      → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it +1 Vote: I do not like it

        he isn't saying that you give a spoiler, in your comment you can add a spoiler section like that one:

        Spoiler
        → Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    all[s]*p[s] is too large for long long. I got 6 penalty from that before splitting it into p[s-20] and p[20]

    → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      But I was getting test case 1 with no problem and in the last case the numbers are greater than 10^18. I don't get why I lost it I w8 until they open the test cases.

      → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
        ← Rev. 2   Vote: I like it 0 Vote: I do not like it

        Mine also passed test case 1 and failed on 2 probably because all[s](number of elements) is small in test case1. (not sure so lets wait)

        → Reply
»
3 years ago, # |
  Vote: I like it +83 Vote: I do not like it

Duh, H was so incredibly unnatural it took me 15 minutes to parse the statement and 45 more to understand it on an intuitive level so that I could even start thinking about it >_>

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +10 Vote: I do not like it

    It looks much more natural if you know about stable matchings. The condition for a matching to be stable is that there are no bad cycles of length 2. Here it's premutation instead of matching and we check cycles of all lengths. And the greedy solution is also similar to stable matching.

    → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      Maybe I don't see something, but the setting that "i-th person has i-th item and some other hypothetical assignment that has absolutely nothing to do with current assignment is optimal if blah blah" sounds absurdly to me. It would make sense for me if "A is not optimal if I can change it locally and get better assignment", but "A is not optimal if I can take some other assignment and change it locally and get better assignment than A" is very artificial

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

    the third agent got an item that is worse for him, but this does not prevent the set $$${1,2}$$$ from being dissatisfied

    Well, agent 3 has good heart and might not be angry, but I was so unhappy with that; So unfair and unintuitive.

    → Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

How to solve F?

→ Reply
»
3 years ago, # |
  Vote: I like it +18 Vote: I do not like it

Solutions to problems like F make you feel so freaking stupid. My dumbass brain kept thinking variations of xor gauss for two whole hours before getting the idea of dsu ╥﹏╥

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +13 Vote: I do not like it

    Yeah lol, I was trying to do xor basis from here for like 1.5 hours before giving up and finding the dsu solution T_T

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

      Well that algorithm is what lead me to idea for solving.

      → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
        ← Rev. 2   Vote: I like it 0 Vote: I do not like it

        you solved problem E very fast after D , have you solved similar problems before ? How you deduced the solution so fast ?

        → Reply
        • »
          »
          »
          »
          »
          3 years ago, # ^ |
            Vote: I like it +1 Vote: I do not like it

          Almost all bitwise operator problems will involve doing something bit by bit, especially math calculation ones. It was then easy to see since xj is in both terms, so you should get sum of xi & xj and xj | xk independently. Then it was just a matter of seeing cases of when to add power of two for each bit.

          I've solved many problems using bitwise operator properties and this one just used more straight forward properties.

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

    Yes, I did the same. I then changed my mind to think about edges and the solution just came to mind. I was THROBBING. But then I arrived at G...

    → Reply
»
3 years ago, # |
  Vote: I like it +25 Vote: I do not like it

Some people were giving solutions of A in youtube while contest was running :/ Youtube Link

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it -7 Vote: I do not like it

    video description says — "please try yourself first" LOL

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

      This guy did the same in Educational Codeforces 101, I hope he will be punished.

      → Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +4 Vote: I do not like it

    This guy is bold enough to put his exact youtube name on a stopstalk profile. The handle is DOUBLE-Agent, and the submission 102793799 almost exactly matches the video. MikeMirzayanov or a CF admin should deal with this; this is much worse than simply copying a solution.

    → Reply
»
3 years ago, # |
← Rev. 2   Vote: I like it +26 Vote: I do not like it

Lot of plagiarism in this contest, many newbies have solve more than 4 problems which is kinda sus.

→ Reply
  • »
    »
    3 years ago, # ^ |
      Vote: I like it +19 Vote: I do not like it

    Solutions were leaked in a telegram group

    → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it +27 Vote: I do not like it

      How do u know?

      → Reply
      • »
        »
        »
        »
        3 years ago, # ^ |
          Vote: I like it -37 Vote: I do not like it

        Your one of the solution is skipped , are you afraid that other people might have copied the same ?

        Do Mike uses MOSS or any other good plagiarism checker ? Because many similar solutions are not caught .

        → Reply
        • »
          »
          »
          »
          »
          3 years ago, # ^ |
            Vote: I like it +35 Vote: I do not like it

          Bruh I submitted E twice since the first one was close to Time Limit

          → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it -13 Vote: I do not like it

      whatever man, hope everyone enjoyed the contest. idc about rating anyway.

      → Reply
»
3 years ago, # |
  Vote: I like it -109 Vote: I do not like it

can anyone tell me why my code has a runtime error on pretest 2 for 1st problem it works on the test given https://codeforces.com/contest/1466/submission/102858058

include

include<stdlib.h>

include

using namespace std; int numberofarea(int arr[], int n) { int area[100]={51}; int diff,areas=0; for(int i=0;i<n;i++){ for(int j=i+1;j<n;j++){ diff=arr[j]-arr[i]; area[areas]=diff; areas++; } } sort(area, area + 100);

// Traverse the sorted array
int res = 0;
for (int i = 0; i < 100; i++) {

    // Move the index ahead while
    // there are duplicates
    while (i < 99 && area[i] == area[i + 1])
        i++;

    res++;
}

return (res-1);

}

main(){ int t,n,x; cin>>t;

for(int i=0;i<t;i++){
    cin>>n;

    if(n==1){
        cin>>x;
        cout<<"0"<<endl;
    }
    else{
            int arr[50];

        for(int j=0;j<n;j++){
            cin>>x;
            arr[j]=x;
        }
        cout<<numberofarea(arr,n)<<endl;
        free(arr);
    }
}

return 0; }

→ Reply
  • »
    »
    3 years ago, # ^ |
    ← Rev. 2   Vote: I like it +3 Vote: I do not like it

    just copying codes from online doesn’t mean that you solved a problem!

    → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it +15 Vote: I do not like it

      It does if you get AC.

      → Reply
    • »
      »
      »
      3 years ago, # ^ |
        Vote: I like it +3 Vote: I do not like it

      i have written this code by myself ,it took me one hour and you are just bluntly calling it copied ,if don't want to help then please don't comment for just getting upvotes.

      → Reply
»
3 years ago, # |
  Vote: I like it 0 Vote: I do not like it

can anybody please tell what's wrong with my submission for D https://codeforces.com/contest/1466/submission/102825313

→ Reply
»
3 years ago, # |
  Vote: I like it +16 Vote: I do not like it

I hate Python.

Problem E is Python's nightmare.

→ Reply
»
3 years ago, # |
  Vote: I like it +26 Vote: I do not like it

System testing seems to be stuck at 40% for a long time now. I wanted to submit for C and E.

→ Reply