By PikMike, history, 3 months ago, translation, In English,

Hello Codeforces!

On Jul/22/2019 17:35 (Moscow time) Educational Codeforces Round 69 (Rated for Div. 2) will start.

Series of Educational Rounds continue being held as Harbour.Space University initiative! You can read the details about the cooperation between Harbour.Space University and Codeforces in the blog post.

This round will be rated for the participants with rating lower than 2100. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.

You will be given 6 problems and 2 hours to solve them.

The problems were invented and prepared by Roman Roms Glazov, Adilbek adedalic Dalabaev, Vladimir Vovuh Petrov, Ivan BledDest Androsov, Maksim Ne0n25 Mescheryakov and me. Also huge thanks to Mike MikeMirzayanov Mirzayanov for great systems Polygon and Codeforces.

Good luck to all participants!

UPD: Our friends at Harbour.Space also have a message for you:

Hello Codeforces!

We hope your summer is going well!

Last Friday we finished the second edition of the Tech Scouts Summer Camp, with 70 participants, 20 different nationalities and many solved problems. We had 6 participants with a full scholarship thanks to the collaboration between Harbour.Space and Codeforces and we are working on increasing this number next year.

We would also like to remind you that we offer scholarships for our technical programmes, such as Computer Science, Data Science and Cyber Security.

They are set in such a way that doesn’t require additional applications — we believe in merit and potential, and so what you put in your application to the university will be our criteria.

You could be just the diamond we’re looking for, but you’ll never know unless you apply!

APPLY HERE→

UPD2: There will be 6 problems in the contest.

Congratulations to the winners:

Rank Competitor Problems Solved Penalty
1 Um_nik 6 111
2 Golovanov399 6 174
3 PinkRabbit 6 190
4 dreamoon_love_AA 6 198
5 _twilight 6 232
6 HIR180 6 252

Congratulations to the best hackers:

Rank Competitor Hack Count
1 greencis 122:-29
2 Ali_Zaiback 26
3 racsosabe 22:-7
4 plusplus6408 14
5 Flamire 14:-3
6 crvineeth97 13:-2
397 successful hacks and 420 unsuccessful hacks were made in total!

And finally people who were the first to solve each problem:

Problem Competitor Penalty
A dorijanlendvaj 0:01
B Um_nik 0:04
C beefman 0:06
D Um_nik 0:12
E Benq 0:11
F Um_nik 0:31

UPD3: Editorial is out

 
 
 
 
  • Vote: I like it
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3 months ago, # |
Rev. 2   Vote: I like it +19 Vote: I do not like it

Hope that Pretest can be strong this edu round. (I'm so afraid of fst). :D

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3 months ago, # |
  Vote: I like it +30 Vote: I do not like it

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3 months ago, # |
  Vote: I like it -89 Vote: I do not like it

Typically for educational rounds (and for this one in particular), is the intention to have strong pretests to try to prevent failing systests, or to have weak pretests to encourage hacking?

Just trying to get a sense for how much I should trust the pretests tomorrow. :)

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3 months ago, # |
Rev. 3   Vote: I like it -33 Vote: I do not like it

Nice

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

Is it truth, that educational contests are a bit easily than usual div2?

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

    It depends whether a participant knows theory well

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    3 months ago, # ^ |
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    Genarally I find them easier because they don't put a troll case like what they do in some normal div2 rounds

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

A user enters the club of young explorers and says: "I am here for the first time". Music stops, and the main young explorer comes to him and answers: "You can read the details about the cooperation between Harbour.Space University and Codeforces in the blog post."

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3 months ago, # |
  Vote: I like it -32 Vote: I do not like it

Round 69. The name itself a MEME

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

    I feel like this MEME gonna get me turn into pale blue again :>>

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

    Such comments should get 69 downvotes for ruining the decorum of this platform

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

    you are really naughty!!

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    3 months ago, # ^ |
      Vote: I like it +54 Vote: I do not like it

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3 months ago, # |
Rev. 2   Vote: I like it +44 Vote: I do not like it

Roses are red, violets are blue,

Wish you a high rating, and hacking points too! xD

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

Nice

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3 months ago, # |
  Vote: I like it +16 Vote: I do not like it

Hope I can become a candidate master after the contest.I only need +21

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

Hope that the statement of the problems is very short and easy to understand. :D

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    3 months ago, # ^ |
      Vote: I like it -16 Vote: I do not like it

    Me too. My English is poor, and the LaTeX in the problems makes them difficult to be translated in Baidu Translator.

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

      Are you sure you are from Nanjing Foreign Languages Institute?

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3 months ago, # |
Rev. 2   Vote: I like it -49 Vote: I do not like it

Again

Pretest needs to be strong.

Accepted needs to appear more.

TLE should not appear.

And no Queueforces or Typeforces or Hackforces or Speedforces please.

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

    You should not tell people what to do!! I smell downvotes coming your way

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

Every time I take part in educational rounds I couldn't solve problem D out.

But in normal round I can solve it (but somtimes fst XP).

Ah, wish all would solve D this time!

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    3 months ago, # ^ |
    Rev. 2   Vote: I like it -8 Vote: I do not like it

    congratulations !! how did you solve d?

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

      YES!!! Hope no fst!

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

        what was your approach to solve it?

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

          My English is poor sry.

          An O(nm) solution:

          Let dp[i][j] be the maximum cost when choosing a[i] as the end of a subarray and the length of the subarray is n (n mod m == j).

          So when j = 0 ,dp[i][j] = dp[i — 1][m — 1] + a[i];

          when j = 1 ,dp[i][j] = max(a[i] ,dp[i — 1][j — 1] + a[i]) — k;

          else dp[i][j] = dp[i — 1][j — 1] + a[i]

          The answer is the maximum of the dp array.

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

            why?Could you post a blog? I'm going to study in your blog, thanks.You can just publish it in Chinese.I am also a Chinese competitor.

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

          And it's nearly 1 am in China, I have to go to bed so I can't leave more details. Bye.

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

            Thanks! amazing solution. Good night.

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

        Hi,what is fst?

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

          FST is short for 'fail system tests'. In Codeforces-format contests, tests are split into pretests and system tests. Before the contest ends, submissions are judged with pretests. Then the latest submissions with 'Passed Pretests' verdict will be judged with system tests, which are stronger. FST means that your submission passed the pretests, yet failed during system testing.

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3 months ago, # |
  Vote: I like it -120 Vote: I do not like it

Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

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    3 months ago, # ^ |
      Vote: I like it -124 Vote: I do not like it

    Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

    Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

    Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

    Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

    Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

    Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

    Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

    Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

    Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

    Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

    Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

    Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

    Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

    Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

    Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

    Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

    Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

    Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

    Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

    Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

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

      "I don't know." * 7 * 20.

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      3 months ago, # ^ |
        Vote: I like it -127 Vote: I do not like it

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

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      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

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      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

      Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?

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

        It's so long that I don't want to count how many questions there is.

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          3 months ago, # ^ |
            Vote: I like it +16 Vote: I do not like it

          Maybe INF.

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

          200 copies of each. The guy really did an excellent job.

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

            I don't want to see it again... I'm curious and click... Then my computer...

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

        Are you a repeater or something?

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          3 months ago, # ^ |
            Vote: I like it -83 Vote: I do not like it

          Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am. Yes, I am.

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

        you can compress it as for(i=0;i<200;i++) { cout<<"Is it rated? Is pretest strong? Is system test quick? Is TLE rare? Is statement short? Is Editorial ready right after the contest? Is it Hackforces or Queryforces or neither?"<<endl; cout<<'\n'; }

        looks like someone need to learn about loops .....

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          3 months ago, # ^ |
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          But maybe that comment is easier to send and harder to read than this one.

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3 months ago, # |
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3 months ago, # |
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Waiting for another queryforces

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    3 months ago, # ^ |
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    3 months ago, # ^ |
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    What does queryforces mean?

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      3 months ago, # ^ |
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      It means rounds with a query problem.

      A query problem means a problem that we have to answer all the queries.

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3 months ago, # |
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Auto comment: topic has been updated by PikMike (previous revision, new revision, compare).

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3 months ago, # |
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I think the setter got lost making testcase 1 of problem C :p

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used a linked list for the first time in my life

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How to solve C & D??

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    3 months ago, # ^ |
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    Problem C.

    Sort the array find all differences of $$$a_i - a_{i-1}$$$ and sort them because we need to take away $$$k$$$ biggest ones. And choose first $$$n - k$$$ differences.

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      3 months ago, # ^ |
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      Why does this work?

      taking difference?

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        3 months ago, # ^ |
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        Array is sorted

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        3 months ago, # ^ |
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        basically u have to choose k-1 indexes from the array so that k subarray can be formed. now choose those k-1 indexes efficiently as ex. if k=3, so choose 2 indexes ,let it be i & j so cost is a[i]-a[0]+a[j]-a[i+1]+a[n]-a[j+1]. now write these terms efficiently so (a[i]-a[i+1])+(a[j]-a[j+1])+(a[n]-a[0]) now for to minimise this expression ,first two brackets should be min. as last bracket is always constant so sort the array(array of differences of a[i]-a[i+1]) and take 2 values (means if k=3) and then add (a[n]-a[0]).. this is yur minimum answer.

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      3 months ago, # ^ |
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      why first n-k???

      if we need to make k subarrays then the cost of k elements form ai−ai−1 will be needed. No?

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        3 months ago, # ^ |
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        Logically, because array is sorted, it is like we are merging n — k pairs to make k subarrays

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Problem #D was very difficult for me... R.I.P my blue dream..

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How to solve problem D?

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    3 months ago, # ^ |
    Rev. 5   Vote: I like it +70 Vote: I do not like it

    There is a common approach to find a subarray with maximum sum: construct an array of prefix sums $$$p$$$, and find a pair $$$l, r$$$ such that $$$r >= l$$$ and $$$p[r] - p[l]$$$ is maximum possible. To do so, we iterate on $$$r$$$ and maintain best possible $$$l$$$.

    Let's modify it for our problem. Suppose $$$l$$$ has remainer $$$x$$$ modulo $$$m$$$. Let's remove $$$x$$$ first elements from our array, and search for best $$$l$$$ only among those that have remainder $$$0$$$ modulo $$$m$$$. To maintain that we should subtract $$$k$$$ a few times from the result, we may insert some elements equal to $$$-k$$$ so we get an array: [ $$$-k$$$, $$$a_1$$$, $$$a_2$$$, ..., $$$a_m$$$, $$$-k$$$, ..., $$$a_{m + 1}$$$, ..., $$$a_{2m}$$$, $$$-k$$$, $$$a_{2m+1}$$$, ...].

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      3 months ago, # ^ |
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      Thank you, I didn't know about this approach with prefix sum. It is really cool, I will study it!

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        3 months ago, # ^ |
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        Could you please explain it in detail i am not able to understand it

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      3 months ago, # ^ |
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      During contest i thought of solution using binary search. we want to maximize:p[r]-p[l-1]-ceil(k*(r-l+1),m) so we fix l and binary search on fun(r)=p[r]-ceil(k*(r-l+1),m) for maximum value, but the problem here is p[r] is not suitable for binary search,but we could instead replace it with p2[r]=max(p[r],p[r-1]), index having negative values are not useful,as we could already have our have our maximum on lower size(r-l+1). now we can binary search on fun2(r)=p2[r]-ceil(k*(r-l+1),m). so for each l=0 to n-1,we get our maximum value. is the above solution feasible,could it work.I tried implementing it but was getting TLE.

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

        Fixing l and finding correct r value by binary searching is not possible as the values won't be monotonous always... What I mean is
        f(l, x) > f(l, x+1) < f(l, x+2).

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          3 months ago, # ^ |
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          k*(r-l+1)/m is monotonous , and we are making prefix monotonous using pfx2[r]=max(pfx[r],pfx[r-1]), as you may notice considering negative values is not useful,as it will never be considered in max contribution.

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      3 months ago, # ^ |
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      Can someone share code with this solution?

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      3 months ago, # ^ |
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      I'm sorry but i don't really understand, how would we iterate over $$$r$$$ while maintaining the best possible $$$l$$$ ? Is this sort of like kadane's algorithm? I would really appreciate it if you could provide some link regarding this.

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    3 months ago, # ^ |
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    using dp i think

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      3 months ago, # ^ |
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      Why downvotes? It can be solved with DP[i][j] = maximum sum if r = i && (r-l+1)%m = j. 57555709 or is it the same thing BledDest mentioned above?

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

      It can be solved with a very simple DP, where DP[i] = maximum subarray ending at index i. Then for the transition we have two choices — the length of the max subarray ending at i is at most m, or it is more than m. First case can be computed in constant time, and for the second case we have DP[i — m] + A[i — m + 1] + ... + A[i] — k.

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        3 months ago, # ^ |
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        I used a similar approach but my solution got hacked could you help me out find the mistake. Thanks in advancw. Here is my submission 57540812

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        3 months ago, # ^ |
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        Really awesome idea.

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

    Here's one way to solve it (57526007).

    1. Miss the constraint on $$$m$$$.
    2. Try random shits and fail.
    3. Decide to ignore the ceiling function and then fire up a CHT. To avoid fuck up, take the best among nearby $$$69$$$ lines suggested by CHT.
    4. Arsenal.
    5. Profit.

    Any hack?

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

      I don't think it would work if the problem was proposed on Educational Round 1.

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      3 months ago, # ^ |
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      Hacked it.

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    3 months ago, # ^ |
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    I couldn't solve it during the contest but later on, after fixating on the O(M*N) constraint, I solved it like this —

    If we pick 1 or 2 or .. m-1, in all cases, we have to subtract k while building the solution. So I built the solution by kind of picking bunches of m elements at a time. While iterating from left to right, solution at i represents the best possible subarray ending at i.

    When you pick m elements at a time, you get two options —

    1) Add all m to previous solution at (i-m)

    2) Leave some (k, ranging from 1 to m-1) gaps in the beginning and start a new optimal subarray from here.

    At every step, take the maximum of the two available options and keep updating the final answer at each i.

    My solution

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3 months ago, # |
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Good contest, thanks)

How to solve E?

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    3 months ago, # ^ |
    Rev. 3   Vote: I like it +19 Vote: I do not like it

    if ini<outi<10^5 it is easy to solve with dp(int max_out,int is_something_used) which return pair, first value is minimum extra space, second is our answer. We can go to dp(max_out-1,is_something_used) or use some matryoshka to skip from max_out to new_ma_out. Know you can convert all values <10^9 in values <2*(n)<2*(2*10^5). This is a solution which i send and get AC 57544668

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

      This is the same idea as to build graph(two adjacent unique values(plus 0) of input in sorted array have edge with weight equal to absolute difference of values, and edges with weight equal to 0 from out_i to in_i) and that you must find number of different ways from larges value to 0 it is easily with Dijkstra.

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Any hint for E?

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What is the 3rd testcase for problem D?

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Will the contest be open for virtual participation before the end of the open hacking phase, or will virtual participation only be available after the results are finalized?

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D was a very cool problem to learn about maximum subarray sum

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Got confused in A for a long time. Thought we can make new planks by joining other planks :(

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Can anyone explain the proof of C?

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    3 months ago, # ^ |
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    if you divide the array into k parts, then cost turns out to be : cost = An — A1 — d1-d2-d3....dk-1 where di correspond to difference between consecutive elements in elements at the partition ends: Ex. — 1 2 3 / 5 6 7/ 10 11 12, here d1 = 5-3, d2 = 10-7.

    So to minimize answer, we need to subtract maximum difference for K-1 differences from An — A1, which can be achieved just by sorting differences.

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3 months ago, # |
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C was similar to global round 1 (B) quen.

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3 months ago, # |
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..

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3 months ago, # |
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Solve task D, but long type is not enough for result... Send solution (5 min after) with BigInteger and get AC (may be somebody crack my solution, but im really sad).

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3 months ago, # |
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How to solve D?

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    3 months ago, # ^ |
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    iterate the remainder $$$i$$$ fo $$$m$$$, and calculate the every prefix sum $$$pre[j](i\le j \le n) = \sum_{k=i}^j a[i] - \lceil {j - i + 1 \over m} \rceil$$$, so the cost of subarray[l...r]=pre[r]-pre[l-1]($$$l \bmod m = i$$$), you can find answer by maintaining maxmium pre or minimum pre.

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Oh. In A, I always thought that two planks can put together to be a longer plank and the second maximum plank can be changed...

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    3 months ago, # ^ |
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    Same here. Was lost in that almost till the end. It might have been a good problem to deal with.

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Is there any point in problem B that input has unique numbers?

We cannot hack with repetitive numbers in test case because codeforces says it's invalid.

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    3 months ago, # ^ |
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    where ai is the radius of the disk initially placed on the i-th pillar. All numbers ai are distinct.

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3 months ago, # |
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Nice Contest :)

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After thinking about subarray sum for a long time and not getting anywhere, I decided to use the ol' divide-and-conquer method to solve D. I've used this "trick" previously to solve a G from another educational round, where the solution was segment tree.

Here is the code — https://codeforces.com/contest/1197/submission/57533758

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    3 months ago, # ^ |
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    I think DNC doesn't work because my solution using DNC just got hacked. Did you prove that it satisfies the quadrangle inequality ?

    Submission : https://codeforces.com/contest/1197/submission/57528146

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      3 months ago, # ^ |
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      Well, I mean the divide-and-conquer paradigm, not the dp technique — my technique is similar to merge-sort.

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    3 months ago, # ^ |
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    can u explain briefly what have u done!!. - your method seems interesting.. `

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      3 months ago, # ^ |
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      Alright.

      This technique in general should work well for places where we want the optimal subarray or so. The function solve(int l, int r) divides the whole array into two parts and checks for an optimal subarray which is a part of either, and in O(n) it checks the subarrays which contains the middle element.

      Time complexity proof is easy — there are logn divisions and you do each of them in O(n), since the length of each interval is 2^x and the number of intervals are n/2^x. Thus, time complexity = O(nlogn).

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    3 months ago, # ^ |
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    Those who were asking about the other problem: see my solution here — https://codeforces.com/contest/1107/submission/49050220

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3 months ago, # |
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I submited my code and wrong answer. After that, I didn't submit any problem. So will my acount unrate in this contest?

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    3 months ago, # ^ |
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    nope, the round will be still rated for you.

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      3 months ago, # ^ |
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      I thought my account would not be rated so i didn'n submit again :((((((((

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    3 months ago, # ^ |
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    I think that if you submit at all, the contest becomes rated for you.

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    3 months ago, # ^ |
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    when u submit code with any verdict at anytime in official time of a contest, this means that you will be a participant and u will be rated after the contest also

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I recently started on codeforces and I can only solve 2 problems atmost and after the contest 3rd seems pretty doable but I cant get it right during the contest. My rating is just getting dropped after each contest and that has got me irritated and sad. Any suggestions on how to improve??

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    3 months ago, # ^ |
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    You should practice more questions Specially topic wise the topics in which you think/know you are weak at..

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    3 months ago, # ^ |
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    I'd say don't worry about your ratings until it stablizes. The initial ratings don't represent much about your skills anyways.
    On how to improve, you can try learning algorithms and make your own library to use in the future.

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Any hints in problem F for one line? I know that should by some matrix multiplication.

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    3 months ago, # ^ |
    Rev. 2   Vote: I like it +60 Vote: I do not like it

    It's impossible to do it in one line, but I'll try to make it short.

    When analyzing a combination of acyclic games, we can almost always apply Sprague-Grundy theory. Let's solve the problem with the following dynamic programming: $$$z[i][j]$$$ is the number of ways to color $$$i$$$ first strips so that the Grundy value of their combination is $$$j$$$.

    To do this, we have to somehow count the number of ways to paint one strip so that its Grundy value is fixed. We can do it with auxiliary dynamic programming: $$$dp[i][last]$$$ is the number of ways to color $$$i$$$ first cells of a strip so that the tuple $$$last$$$ represents the values of Grundy of the last several cells. Since our moves are limited to shifting the chip at most $$$3$$$ cells backwards, we have to store only $$$3$$$ last Grundy values in this tuple. And since we have at most $$$3$$$ different moves, each Grundy value does not exceed $$$3$$$, so there are only $$$64$$$ different values of $$$last$$$ we are interested in.

    To speed this up, we can skip long uncolored segments by converting the transitions of this dynamic programming into a $$$64 \times 64$$$ matrix (let's call it $$$T$$$) and using binary exponentiation of this matrix. The common version of matrix exponentiation may be too slow (this solution will work in $$$O((n + m) K^3 \log A)$$$, where $$$K$$$ is the number of rows in $$$T$$$), so we should speed it up. One common way to do it is to notice that every time we need to skip a long uncolored segment, we have to multiply the transition matrix (which is the same every time we need to do so), raised to some power, by the vector of current dp values. So, instead of naively exponentiating $$$T$$$, we may precalculate $$$T$$$, $$$T^2$$$, $$$T^4$$$, $$$T^8$$$, ..., $$$T^{2^{30}}$$$ and multiply the matrices we need by this vector, and it reduces the time we spend on every uncolored segment to $$$O(K^2 log A)$$$.

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

      Thanks. I mean how to find answer for n = 1 (one line). It is quite detailed explanation.

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What's wrong in this logic for problem C? Code

I used binary search.

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I try to hack one solution of problem 'A' using this code.. But it shows "invalid input". Any Reason??

include <bits/stdc++.h>

using namespace std;

int main() {

cout << 1 << "\n";
cout << 100000 << "\n";
for(int i = 0; i < 100000; i++) {
    cout << 100000 << " ";
}
cout << "\n";

return 0; 

}

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3 months ago, # |
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Problem C was very similar to this problem asked in Global round 1.

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3 months ago, # |
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Why is there one person with so many hacks in problem A?

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    3 months ago, # ^ |
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    I noticed that all hacked submissions in problem A are written in Java, so i think the problem is with sort (in some specific cases it can run in o(n^2) instead o(nlogn)).

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      3 months ago, # ^ |
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      nice, my solution also hacked

      My thinks during 1st task: "Do not use sort, just store 3 maximum elements", but lazy won.

      Is there some info about worst cases for java Arrays sort?

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        3 months ago, # ^ |
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        I think that it will run in o(n^2) for arrays that are almost sorted, but i am not certain.

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        3 months ago, # ^ |
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        As far as I remember, int array in java uses QuickSort, a workaround for this is to use an Integer array which uses MergeSort instead.

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          3 months ago, # ^ |
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          Yeah, I found on codeforces forum discussions. Top contest for me (life education), one hacked, other has correct solution but too late because of wrong work with types

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    3 months ago, # ^ |
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    Well I just got hacked by him, and now my rating is projected to drop 30 points. How lovely :)

    Btw I used C.

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      3 months ago, # ^ |
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      You got TLE ? If yes it's coz you used inbilt qsort in c whose worst case time is O(n^2) . Either shift to c++ or use your own custom merge sort implementation

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        3 months ago, # ^ |
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        I don't know how to see if it's TLE or not, but yeah I used qsort

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3 months ago, # |
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From past few contest i keep getting stuck at Problem A , in most cases i was not not able to understand the problem properly , which leads me to huge time loss . Same thing happened to me today . I feel B was pretty easy . Solve it in 10 min using 2 pointer . I tried so hard to become pupil , but i am unable to achieve this simple thing too .

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    3 months ago, # ^ |
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    Goddammit, The exact same thing is happening with me too..... last 3-4 contests either i was being complacent or i don't what I am unable to solve A.... B/C are good go's for me from some time now..... Even I want to get out of this newbie rut, but it looks like i have to work hard and solve more, duh!

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3 months ago, # |
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Can someone please explain how to approach for Problem E..?
Thank you.

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    3 months ago, # ^ |
    Rev. 3   Vote: I like it +11 Vote: I do not like it

    Without loss of generality the dolls are ordered such that out_1 <= out_2 ... <=out_n

    Key observation. Fix j<i and consider all arangements such that the smallest matrushka is i and the largest is j, then the arrangement amongst these that minimizes empty space is already maximal with respect to number of matrushkas.

    Now we describe a quadratic solution. Let m[i] be the minimum possible extra space in a maximal arrangement such that matrushka i is the biggest matrushka (maximal among arrangements containing only matrushka i and smaller matrushkas). Now let q[i] be the number of such arrangements. We provide a method to calculate all m[i] and q[i] increasingly:

    Step 0: initialize m[i] = INF and q[i] = 0;

    Step 1: iterate through 1 to i-1 and for each doll j that fits inside doll i do m[i]=min(m[i],m[j] + in[i] — out[j]).

    Step 2: iterate through 1 to i-1 and for each doll j that fits inside doll i such that m[j] + in[i] — out[j]=m[i] add q[j] to q[i].

    Now, in order to make this nlog(n) instead of quadratic we use a persistent segment tree and an implicit persistent segment tree.

    in order to do step 1 we just need a segment tree that saves in position out_j the value m[j] — out[j], and to find the best one that fitst we just query for range (1,in[i])

    in order to do step 2 we need persistance, let version T_k of the segment tree only contain the updates of j if out[j]<= k. Then the sum of all the q[j] we need is simply the value stored in position m[i] — in[i] of the tree T_(in[i]).

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3 months ago, # |
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My A got TLE: link

Why? Is this all because I used Java?

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    3 months ago, # ^ |
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    Arrays.sort uses quicksort for primitives and mergesort for objects. It's possible to hack you with an adversarial case such that quicksort takes quadratic time. You can avoid this by sorting an array of Integer rather than int.

    greencis got me with this before too — 55176174 :)

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      3 months ago, # ^ |
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      Wow! I didn't know that. I guess it is the best lesson I could have learned from a div2 A problem.

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        3 months ago, # ^ |
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        I was lucky to learn this lesson by submitting an unofficial solution after Educational Codeforces Round 66 (Rated for Div. 2) ended (I didn't compete in that round) and somehow still getting hacked, so I got the lesson for the low cost of 0 points. :)

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        3 months ago, # ^ |
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        It seems this lesson is getting more expensive. I did the same thing in C. Go ahead and hack it.

        I literally screwed up. lol

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          3 months ago, # ^ |
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          Good news, because the adversarial array would have all distinct positive integers and is the differences of the input array, the maximum input size where the input values don't exceed $$$10^9$$$ is approximately $$$N \approx \sqrt{2 \cdot 10^9} \approx 44000$$$. And it turns out $$$O(N^2)$$$ is still reasonably fast for this case. As a result, I think you will not get hacked.

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        3 months ago, # ^ |
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        i know that feel, bro) in my case I also have D task AC 10 min after contest

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3 months ago, # |
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I saw many people using segment tree to solve D. Can anyone explain this in more detail? (the whole algorithm) ^^

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3 months ago, # |
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When will the rating change due to this competition. Mine is same.

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    3 months ago, # ^ |
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    When did usually change? I wonder, too.

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      3 months ago, # ^ |
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      It usually changes 2 hours after the contest has ended.

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      3 months ago, # ^ |
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      System Testing is running now. So wait a minute.

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        3 months ago, # ^ |
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        is it over now.

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          3 months ago, # ^ |
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          Yes — It went very slowly.

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            3 months ago, # ^ |
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            Are you able to see your changed ranking. I dont think they have updated the rankings yet.

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              3 months ago, # ^ |
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              It's changed, and I didn't participated in this contest.

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3 months ago, # |
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why does this binary search approach fail in problem C , I am searching for minimum possible difference almong all the different that will result in k partition. https://codeforces.com/contest/1197/submission/57575150

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    3 months ago, # ^ |
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    Binary search will not work for this problem. Try this testcase:

    5 2

    1 4 5 7 8

    Correct ans is 4 by partitioning in the following: [1][4 5 7 8]

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3 months ago, # |
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Good contest ,but...

System test and rating change are SOOOOOOOO SLOW!

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    3 months ago, # ^ |
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    Are rankings change complete, cause I am not able to see my ratings change.

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3 months ago, # |
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How my solution for A was hacked. I did the same as others did.Is there anything to care about in java?

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    3 months ago, # ^ |
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    primitive arrays ure quicksort, object arrays use mergesort, so, for sorting, Integer array is better

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3 months ago, # |
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I have a complicated feeling after the contest.

Happily,I became an expert again as soon as I wrote this.

However,because of my rating,I will be unrated if I participate in the next div3 contest.o(╥﹏╥)o

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3 months ago, # |
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Will Editorial be posted?

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3 months ago, # |
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I use my friends written sublime snippet to generate code and as a result some specific codes of us are same and his submission got skipped. I am also learning programming from him.

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3 months ago, # |
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I come with something for problem D but I can't develop it to a solution if anyone solves it by the help of the following please tell me:

we deal with the array as the blocks, we try each possible one let's call it j from 1 to m, and for every j we try to start from 0 to j — 1 and move by j step to partition the array.

it does nothing but I think it could be developed in some way.

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3 months ago, # |
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MEMETIMEWAIT

..

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3 months ago, # |
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Can anyone help me in question D. I am getting TLE on test 3. please describe your approach towards problem.

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3 months ago, # |
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Not sure if anyone else did this, but my solution for B actually uses Binary Indexed Trees. https://codeforces.com/contest/1197/submission/57523003

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3 months ago, # |
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Auto comment: topic has been updated by PikMike (previous revision, new revision, compare).

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3 months ago, # |
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Probelm B Div2 57582495

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    3 months ago, # ^ |
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    can you explained your approach for solution ... i solved it using concept that , I iterated loop from i=1 to i=n-1 on given array set . and checked that if there exists any a[i] which is smaller than both a[i+1] and a[i-1] , if exists then ans is NO else YES .

    i saw many people solutions, they approached it in a different way like you . can you elaborate ,what you did???

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2 months ago, # |
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Can anyone explain to me what "hacking solutions" means and how to do it please?

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    2 months ago, # ^ |
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    Hacking a solution means passing a custom test for someone's submission. If submission and author's code return different answers or any other failure happens then solution is hacked and the authon loses his points.