Supermagzzz's blog

Codeforces Round #644 (Div. 3)
By Supermagzzz, history, 5 years ago, translation, In English

Hello, Codeforces!

We have planned this round as a Div. 4, but testing showed us, that problems are more suitable for Div. 3. Therefore, instead of the previously announced Div. 4 we will hold Div. 3 round.

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Hello! Codeforces Round #644 (Div. 3) will start at May/24/2020 16:35 (Moscow time). You will be offered 8 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating 1600 or higher, can register for the round unofficially. The round will be hosted by rules of educational rounds (extended ACM-ICPC). Thus, during the round, solutions will be judged on preliminary tests, and after the round it will be a 12-hour phase of open hacks. I tried to make strong tests — just like you will be upset if many solutions fail after the contest is over.

You will be given 8 problems and 2 hours to solve them.

Note that the penalty for the wrong submission in this round (and the following Div. 3 rounds) is 10 minutes.

Remember that only the trusted participants of the third division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as trusted participants of the third division, you must:

  • take part in at least two rated rounds (and solve at least one problem in each of them),
  • do not have a point of 1900 or higher in the rating.

Regardless of whether you are a trusted participant of the third division or not, if your rating is less than 1600, then the round will be rated for you.

The problems for this round were invented by MikeMirzayanov and prepared by me and Stepavly

Thanks to MikeMirzayanov for platforms and coordination of our work. Thanks to antontrygubO_o, iankury, bfs.07, kocko, Ilya-bar, arsijo, pashka, Gassa, neal, vovuh for help in round preparation and testing the round.

Good luck!

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UPD: Editorial is out

  • Vote: I like it
  • +348
  • Vote: I do not like it

Comments Comments (179)
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5 years ago, # |
  Vote: I like it +19 Vote: I do not like it

Look forward to this round. Thanks for offering div 3 and 4!

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

the pawns strike back

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5 years ago, # |
  Vote: I like it +56 Vote: I do not like it

Finally other author than vovuh for div3 contest

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    5 years ago, # ^ |
      Vote: I like it +82 Vote: I do not like it

    Last time vovuh wasn't one of the authors of a Div3 contest was 23 Div3 contests ago!!

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

      As the contest was prepared to be a D4 one, also everyone knows that vovuh doesn't prepare D4 contests(at least until now), so there is no vovuh as an author here.

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

      I hope that you rock this round. All the best chota haath mota pait.

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

    Because of the round previously announced as div. 4 :D

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    4 years ago, # ^ |
      Vote: I like it -47 Vote: I do not like it

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

      This made me LOL, at least provide translation if you don't want downvotes lol

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

        Hiruem chill h bro! Ye apne(indian) he hai jinhe samajh me sab aata h par phir bhi downvote karte h! Par apne ko ghanta pharak nhi padta bas thodi hasi thitholi ho jaye wahi bahut hai. I dont know why they cant take things as a joke.

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

Great!

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

The time link always shows the Moscow time rather than the local time, please fix it

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5 years ago, # |
← Rev. 2   Vote: I like it +53 Vote: I do not like it

Div4 was an experiment. Keep maintaining the standard of Codeforces.

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

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

[deleted]

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

Thanks for the div3 instead of div4 :)

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

This weekend is lit , as CF contest at 7pm IST and at 9.30 Codechef Cookoff . Noice

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

    Yup. And then 2 codeforces round + lunchtime this week!!

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

MikeMirzayanov Do you have any plan to run Division 4 regularly?

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

    That was supposed to be div4. So, i think yes, he do.

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

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5 years ago, # |
← Rev. 2   Vote: I like it -31 Vote: I do not like it

[Исключен]

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

    did you even bother reading the first line of this blog...

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

    You are accepted anyway, isn't that great!

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

Where is vovuh :|

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

First time there will be 8 problems in Div3!!!

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5 years ago, # |
  Vote: I like it -35 Vote: I do not like it

Is it rated since Division was changed from 4 to 3?

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

    When it was div4 then it was rated for div4. Now it is div3 so it is rated for div3.

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

Every time contest is organised after so many days, I get excited. It's other thing that I'm not able to solve more than 2 or 3 problems in contest.

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

I'm starting to miss vovuh already. :(

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

not div 4 Orz

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

We missing out on a potential DIO meme here xD.

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

Can anyone suggest best apps for writing code like codeblocks ( other than codeblock) for a windows user

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

Isn't it unfair that those who have ratings 1599 can participate in the contest and make their ratings 1800+ but those with rating 1601 can't change their ratings?

You will be offered 8 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600

I'm sorry but I have found candidate masters who find questions from div 3 contests interesting.

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

    So,what should be the boundary? If it is x, will not it be unfair to people with x+1 rating? :v

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

      One solution may be to cap the maximum achievable rating in div3 contests to 1600.

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

        It is a matter of fact that nearly all reds started at aprox 1580-1595 and then instantly jumped over 2000... where they happily lived ever after. Not.

        What is this nonsense about? You where below 1600 for like two years.

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

    Codeforces never let someone stay above his skill level. If someone has skill level for rating 1600 then if he somehow gets 1800 rating then he will come back to 1600 within two contest. If someone gets uneven rating increment in one contest then he will distribute it in next contest. He will not take the rating home and sell it in local market. Codeforces will never let him carry a rating which he doesn't deserve. So one uneven increment doesn't matter too much.

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

    I find a master who thinks div3C is too hard for my level. Yes. He is myself.

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

    This is a platform for practice so,if u are looking for placements wise even if u are expert company will hire you, if you are skilled. Happy coding!!. Take it in positive.

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4 years ago, # |
  Vote: I like it +16 Vote: I do not like it 
_The problems for this round were invented MikeMirzayanov and prepared by me and Stepavly._

Please insert by before Sir MikeMirzayanov

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

Finally a contest after so many days. It will now be rated for me. Excited!

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4 years ago, # |
  Vote: I like it +117 Vote: I do not like it

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4 years ago, # |
← Rev. 3   Vote: I like it +1 Vote: I do not like it

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

8 problems!! This will be fun.

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

And here we go "A non-vovuh Div3 round" after consecutive 23 Div3 rounds. Hats off to vovuh for this 23 round streak. Good luck to new authors.

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

Maybe you could add one or two easier problems and delete the hardest problem, and then the contest could be div3 and div4, just like div1 and div2 in the past.

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

Will the problems include sub-tasks?

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

Can someone elaborate on what this line means:

do not have a point of 1900 or higher in the rating.

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

    If someone has maximum rating 1900 or more then he will not be considered as trusted participant.

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

      Can someone elaborate on what this line means: trusted participan

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

        Sometimes some high ranked coder make fake account and participate in div3 rounds. So they get high rank on that contest. As a results, real participants can't know their real position in div3 contests. So, people who din't participate in at least two rated contests, then he will not be a trusted participant to stay in final standing. So, there will be no fake account on final standing and real participants can know their real position on standing.

        A high rank coder can loose rating on purpose to reach less than 1600 points and get a good rank officially in div3 rounds. So if a contestant has 1900 or more maximum rating then if loose rating towards less than 1600 them he will also be not considered as trusted participant and will remain out of final standing.

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

Good luck to all! Live solving the problems 15 mins after the contest finishes:

https://youtu.be/gFepyRGn1vs

Only on Algopedia!

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4 years ago, # |
← Rev. 3   Vote: I like it +6 Vote: I do not like it

To be honest,vovuh & MikeMirzayanov always makes nice problemset:)

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

Eid Mubarak to all the contestants. Hope it will be a great contest for us before EID.

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

It is div4, lol.

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4 years ago, # |
← Rev. 2   Vote: I like it -35 Vote: I do not like it

[deleted]

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4 years ago, # |
  Vote: I like it -6 Vote: I do not like it

It should not have been a div3.

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

I didn't receive a reminder email

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4 years ago, # |
  Vote: I like it -33 Vote: I do not like it
The comment removed because of Codeforces rules violation
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    4 years ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    WHAT?! This is the first time I see that codeforces removes comments

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

      From time to time somebody talks about problems while contest.

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

Video Tutorial for today's G

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

Quick editorial in Python. For more editorials visit this discord: http://interview.solutions

Question A
Question A - Tutorial
Question A - Code
Question B
Question B - Tutorial
Question B - Code
Question C
Question C - Tutorial
Question C - Code
Question D
Question D - Tutorial
Question D - Code
Question E
Question E - Tutorial
Question E - Code
Question F
Question F - Tutorial
Question F - Code
Question G
Question G - Tutorial
Question G - Code
Question H
Question H - Tutorial
Question H - Code
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    4 years ago, # ^ |
      Vote: I like it +3 Vote: I do not like it

    Men, thank you so much, you make this editorial faster than the speed of light

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4 years ago, # |
← Rev. 2   Vote: I like it -7 Vote: I do not like it

Problem G better version: https://vjudge.net/problem/LightOJ-1330

Solution available on net.

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

1st time I solved 6 questions in a contest. Yipee!!

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

Can anyone help me with what peculiar case can be in Case#2 of problem F ?
I kept getting WA on Case#2.

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

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

G is same as lightOj 1330.

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

    Not the same because you are not asked to output the lexicographically smallest, but is true that the solution of LightOj works for today's G

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

Why greedy isnt working for G?

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

    The greedy I came up with would give "NO" for 3 3 2 2

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

Can someone tell me why this got TLEd - https://codeforces.net/contest/1360/submission/81243429 and this got accepted - https://codeforces.net/contest/1360/submission/81245539

Both are exactly the same code.

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

Seriously it's div3. Nope. I think it's the actual div4. Where you would have trivial A, B, C, D, E and not so trivial F, G and really hard H. G was super cool though. Felt like a fool after solving this.

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4 years ago, # |
← Rev. 2   Vote: I like it -15 Vote: I do not like it

The input data of Problem H is 6MB at worst. Using cin will get TLE, using scanf will not get data because of strange '\n', using some other library also fail. A problem's difficulty should be how to solve it, not how to input it!!

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

    I didn't believe there was an issue with problem G, since I solved it using cin, with the same expected complexity as given in the editorial.

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

    Check the editorial. Our solution use cin and get AC.

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

MikeMirzayanov Does increasing the number of questions of DIV4 makes the round DIV3? I hope thats not true for DIV2 round.

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

    I (personally) don't think so, since usually some contests that are harder or have more problems have their time extended, instead of increasing their division. Also, I (again, personally) believe problems G and H were more suitable to a div. 3 contest, rather than a div. 4 contest.

    Then again, I did not participate in the problem-setting nor testing of this round, so who knows ¯_(ツ)_/¯

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

I actually spent more time debugging than reading and thinking combined..

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

Can anybody kindly show me a test case where this bruteforce(!) solution fails?

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

    1

    2 3

    bbb

    baa

    the answer could be "bab" , your solution prints -1.

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4 years ago, # |
  Vote: I like it -39 Vote: I do not like it

I hope this is the first and last div3 that you organised.

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

Can I see due to which test case my solution was hacked>?

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

What is the best time complexity one can achieve for problem F ?

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

    Definitely this is not the best, but let's analyze this:

    Take i-th string. Then for each position j, you try each of the N letters in the j-th column of input. There are N*N*M possible strings making this procedure. Then you need to check if that string works, in N*M complexity. Final complexity of this is O(N^3*M^2). I wonder if there's a O(N*M) solution

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

    O(N*M) is possible: https://codeforces.net/blog/entry/77846?#comment-628882

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

For the first time in my life solved 5 problem. Thanks to the authors.

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

In F , I used the brute force concept and my run time complexity was O(n^3*m^2). How to solve it with larger constraints ?

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

    It can be solved in O(26*N*M^2) by trying to change every letter in the first string, to every possible value. Then you check if that string works.

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

This div3.5 contest was awesome

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

I think it was better to keep it div4. Div 3 E F problems are generaly much harder than all of these problems.

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

MikeMirzayanov

This two people are copying codes i guess https://codeforces.net/contest/1360/submission/81303569 and https://codeforces.net/contest/1360/submission/81306780 other solutions of them are also similar. Their previous contest submission are also same. Sorry for bad english. Please look into such acts.

Edit: I just saw that all their submissions are similar. They are taking plagiarism to next level.

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

    you forgot to mention that they are from the same university in Indian. And... they have the same rating graph =))

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

Can anyone help me with what peculiar case can be in Case#2 of problem F ? I kept getting WA on Case#2 https://codeforces.net/contest/1360/submission/81313261

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

I used bitmask dp to solve F in O(t*(1<<n)*m*n^2) and It got accepted in 31ms ... Can anyone provide a testcase which can find the upper bound of runtime .....here is the submission — 81323908

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

    I did the same but i forgot to mark my visited array because which my solution is running exponentially and guess what.. it still got accepted

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

    I think this will pass. In the recent educational contest my soln with 3e8 operation got accepted with 900ms.

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

      Actually I know this will get accepted....My problem is that it got accepted in 31ms which I didn't expect and it's 0(10^8). While O(10^9) shows tle in 5 sec....

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

how did you guys approach, your thought process to find out how to arrange all the one's

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4 years ago, # |
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I used a network flow to solve G lol. Anyone else?

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

    Can you please tell how to apply network flow here?

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

      You can build $$$n$$$ nodes on the left and $$$m$$$ nodes on the right, representing the rows and columns. And link an edge from every row to every column, with capacity $$$1$$$. Then link an edge from the source to every row, with capacity $$$a$$$. Also an edge from every column to the sink, with capacity $$$b$$$.

      If the edge from the $$$i$$$-th row to the $$$j$$$-th column is full, put $$$1$$$ on $$$(i,j)$$$.

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

        Thanks for reply. But i have a doubt. Can you please tell — since the graph will not be unit-graph so complexity will be $$$O(V^2E)$$$ instead of $$$O(EV^{1/2})$$$ for unit-graph. Also edges will be of order $$$V^2$$$ So for $$$1000$$$ test-case time will be $$$O(1000*(50)^4)$$$ but still it's not giving TLE. why? Am i wrong in computing complexity? Please Help.

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

          Oh it seems I got the complexity wrong. I didn't realise $$$E=n^2$$$ and thought it is $$$50^3$$$ per testcase. I don't know why it isn't giving TLE, maybe on such special graph the complexity is actually lower?

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

Can some cool guy explain the fact that when anyone ask "Is it rated",he must get many downvotes

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

    Generally, it is written in the announcement if the contest is rated or not.

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

Why do ppl still do that? :) Was that supposed to hide from hack?

=> 81289430

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

    maybe to not get caught by a plagiarism checker

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

Pretests for Problem D were quite weak..... Lot of problem D solutions were hacked.... Felt demotivated after hacked question, as it affects rankings a lot.....

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    4 years ago, # ^ |
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    I'm so sorry I was upvoting your comment but it got downvoted. What did I do I'm so sorry!

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4 years ago, # |
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Has the system testing finished? If so when will the ratings change?

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4 years ago, # |
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Why am i still unrated even after participating in the contest and given solution 3 problems?

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    4 years ago, # ^ |
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    Cuz they haven't given out the rating updates yet. Look system testing started. It'll happen soon enough I guess.

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      4 years ago, # ^ |
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      Ok I am new to this site . Thanks for helping out

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4 years ago, # |
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If you had felt that the problems are bit difficult for DIV4 you should have put some easy problems in place of those hard problems and make the contest as DIV4. I think the problems are easy for DIV3.

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4 years ago, # |
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Will i be awarded points for successful hacks in this contest... If Yes then how will it be adjusted to the final rankings

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    4 years ago, # ^ |
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    No, you won't be awarded any extra points for a solution hack. It's just that it will affect others' solutions after the system test, and your rank might move up the table (because of others moving down).

    Hacking doesn't yield extra points in Educational and Div 3 rounds (both follow extended ICPC rules for scoring).

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4 years ago, # |
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A very fast system test today after quite some time. Even after the number of participants.

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4 years ago, # |
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My first screencast. Would take suggestions to improve.

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4 years ago, # |
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I would like to appreciate MikeMirzayanov and his whole team for an amazing round. There was no queue during the contest and it ran very smoothly. So it was great work by codeforces team. I hope future rounds are going to be the same one as this.

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4 years ago, # |
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Dang its been almost 3 hours since the system testing finished, how come no rating update yet?

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4 years ago, # |
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why is my rating not changing even after the final standings of the contest are out

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4 years ago, # |
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for F question. I haven't copied the code and it is entirely different anyways...please resolve the issue asap. I think this may be caused due to the input reader method. Not the logic of the question. manish_98 solution: https://codeforces.net/contest/1360/submission/81281906 my solution: https://codeforces.net/contest/1360/submission/81299107

update : issue resolved by Mike :)

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4 years ago, # |
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Funny that my first time I solved 5 problems, I decreased in rate :P

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4 years ago, # |
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Can someone explain how this user went to CM without solving even a single problem?

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    4 years ago, # ^ |
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    I think it's because of changes made for the new rating distribution, and I think they messed up somewhere.

    According to the post, that user should get -100, but since the first contest displays a rating of 500 + (rating that the user should differ by in the contest), the user was able to get +400 rating.

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4 years ago, # |
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Wow, is this even real?

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    4 years ago, # ^ |
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    bug?

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      4 years ago, # ^ |
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      Probably. The latest contest's rating changes are rolled back right now. I hope mine will change to make me an expert :P

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4 years ago, # |
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What the hell! New Ids becoming Master/International Masters with +800 Rating.

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4 years ago, # |
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I see many success stories on the way titled "How I became an International master in 2 hours "

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4 years ago, # |
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I have observed that problems in CF Round #644 (Div 3) were quite easy. Except the last, all problems had 2000+ successful submissions during the contest. Due to this, the rating of participant in 1400-1600 exploded. Adding more to this, new accounts became masters just by solving 2 problems last night. LOLzz.

This might be due to new rating system. However, this completely destroys the motive of the new rating mechanism, that was to reduce creation of new accounts.

I propose two points after seeing what happened:

  1. Withdraw the new rating system.

  2. Make prev. round unrated for participants who were in 1400-1600 before the contest. As the problems were indeed suitable for Div 4 contests only.

Comment if you agree/disagree with my proposal.

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    4 years ago, # ^ |
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    First one is more appropriate

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    4 years ago, # ^ |
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    Disagree. When the problem setters already claimed that this set of problems was more suitable for Div 3, then why debate on it? They have much more experience (along with better coding skills) than us. And, don't forget that among those 2000+ successful submissions, there are also submissions made by unofficial contestants.

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4 years ago, # |
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rating changes are rolled back already

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4 years ago, # |
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I become expert today for the first time..That's a great feeling .

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4 years ago, # |
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From my profile page, Rank displayed is 6204.

Whereas from the contest's standing page, it's 8146. Is this a bug or is there some reason behind it?

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    4 years ago, # ^ |
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    The rank which you are seeing on the contest standing page also includes the particants with rating above 1600(i.e the ones not eligible for Div3)

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4 years ago, # |
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Can u explain me Spy Strings

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4 years ago, # |
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There is a problem in test case 2 (20) in problem 2.

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    4 years ago, # ^ |
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    Let me guess: You solved it, but the grader says "wrong answer".

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      4 years ago, # ^ |
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      Yes. What is the problem here? I solved it manually also, it shouldn't be answer it shows.

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        4 years ago, # ^ |
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        If you link your submission propably somebody can tell you.

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