Endagorion's blog

Codeforces Beta Round #99
By Endagorion, 13 years ago, translation, In English

Hello.

Today round is prepared by me. My name is Mikhail Tikhomirov, i am fourth grade student at mech.-math. dep. of MSU, also i work as developer-researcher at Yandex.

I want to thank Artem Rakhov (RAD) for valuable help and thoughtful coordination, Maria Belova (Delinur) for great-as-always translating statements into English, and alsoMikeMirzayanov for letting us all get together today. =)

Round will be for both divisions. Every division will have five problems as usual, some of them will be the same, some will be not.

Score distribution:

Div1: 500-1000-2000-2000-2500.

Div2: 500-1000-1500-2000-3000.

Today round is the last round in 2011. I want to thank Codeforces team, everyone who invented, prepared or helped in preparing problems this or past years, and those, who help developing the project. Codeforces now is not just a platform for programming competitions, it is a place where everyone can learn something from another, get a bit of knowledge from more experienced fellows, become more advanced by solving contests and trainings, or just enjoy cool and beautiful problems.

Let's wish the Codeforces project good luck in development next year and long years of existence.

Wish you luck. Have fun during the contest and show your best.
Happy new year! =)

UPD:
Round finished. Thanks everybody! Hope you enjoyed it.
Winners:
Div1:
1. ivan.popelyshev
2. al13n
3. WJMZBMR
4. yeputons
5. romanandreev
6. dolphinigle
7. wata
8. Shef
9. shangjingbo
10. azizkhan

Div2:
1. s-quark
2. wayne-ho
3. emrevarol
4. agh
5. lzqxh

Due to some techinical problems, server was unavailable for few minutes before the end of the contest. Out of two unpleasant options: make the round unrated or stay as it is, we choose the second one as it affects the less number of contestants. We apologize to those participants who are affected by this.

UPD2: Editorial is finally translated.
  • Vote: I like it
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13 years ago, # |
← Rev. 3   Vote: I like it +7 Vote: I do not like it

The score of problem E(Div.2) is 3000! Unusual!

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13 years ago, # |
  Vote: I like it +14 Vote: I do not like it
Merry Christmass for you all.
It's Christmass now in indonesian ^_^
I got a gift from Codeforces : 
Beta Round #99
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13 years ago, # |
← Rev. 2   Vote: I like it +1 Vote: I do not like it


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13 years ago, # |
  Vote: I like it +13 Vote: I do not like it
Merry christmas everyone!
I also wish the whole codeforces team a very successful year 2012 and wish all the participants high ratings and great accomplishments!

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13 years ago, # |
  Vote: I like it +22 Vote: I do not like it
Readforces has come again...
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13 years ago, # |
  Vote: I like it +6 Vote: I do not like it
Problem B was out of my mind...Can someone explain what problem B really is....
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    13 years ago, # ^ |
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    I don't know too!
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    13 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    You have to paper a room using one wallpaper only. However, multiple room can have same wallpaper. So, for each room you go through all the wallpapers and decide which one to buy.
    Now, according to the given conditions, stripes must be vertical, i.e, the length of the wallpaper should go along the height of the walls. So, if length of wallpaper < height of the room. Cost is infinity.
    Also, the wallpapers should only be glued vertically, i.e, when you cut the roll in pieces you have to discard the paper that is less than height of the room. For eg, If length=10, h=3. it will be cut in 3 pieces of 3 height. The 1x3 cut will go to waste.
    You can assume that there is one wall with length=2*l+2*w and height=h, for a single room.
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13 years ago, # |
  Vote: I like it +9 Vote: I do not like it
You should extend the contest. Server wasn't responding during (at least) one last minute.
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    13 years ago, # ^ |
      Vote: I like it +8 Vote: I do not like it
    I was trying to hack, and had a test ready 70 seconds before the end, but it wasn't submitted when I pressed "hack".
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      13 years ago, # ^ |
        Vote: I like it +16 Vote: I do not like it
      Well, now I'm not disappointed: this hack wouldn't affect my awesome 2nd place :).

      P.S. Аааа, я на глагне!111
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        13 years ago, # ^ |
          Vote: I like it +3 Vote: I do not like it
        Even though I got the rating increase I think that this contest should be unrated...
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13 years ago, # |
  Vote: I like it +2 Vote: I do not like it
I can't submit in few last minutes (502 Bad Gateway) :(
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13 years ago, # |
  Vote: I like it +15 Vote: I do not like it
Hard Contest :\
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13 years ago, # |
  Vote: I like it +15 Vote: I do not like it
I don't think this is a good contest.It is hard for me to understand the meaning of the description.
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    13 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    yeah, I think so. I don't know the meaning of the problem B yet.
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    13 years ago, # ^ |
      Vote: I like it +1 Vote: I do not like it
    I got a Accepted at problem C, the decription of the problem is very bad , I think ,not only at this problem. " The total length of the lines does not exceed 104 " don't you think this sentence is strange？
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13 years ago, # |
  Vote: I like it 0 Vote: I do not like it
I also ca not submit during the last minute.......which is very serious for me.....sad
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13 years ago, # |
  Vote: I like it +1 Vote: I do not like it
Hi there
I have submitted a problem in last few seconds but got a 504 error! And now it's not submitted!!! :(
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    13 years ago, # ^ |
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    it also affected me seriously...

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      13 years ago, # ^ |
        Vote: I like it +1 Vote: I do not like it
      Cool story, bro.

      It isn't something strange that server becomes very slow for last few minutes, isn't it?
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        13 years ago, # ^ |
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        oh yeah! I should have done it faster!!! :'(
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        13 years ago, # ^ |
          Vote: I like it +4 Vote: I do not like it
        yes, but there is a difference between "server works very slowly" and "server doesn't work"
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          13 years ago, # ^ |
            Vote: I like it 0 Vote: I do not like it
          by the way my problem hasn't been submitted and I don't know What should I do with my new rating now!!!
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            13 years ago, # ^ |
              Vote: I like it +18 Vote: I do not like it
            You should do nothing.
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    13 years ago, # ^ |
      Vote: I like it +3 Vote: I do not like it
    Same, couldn't submit my solution to D (after fixing a bug) for the last 1 minute and 30 seconds of the contest because of a 504 error.
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      13 years ago, # ^ |
        Vote: I like it +3 Vote: I do not like it
      same here, couldn't submit B :(
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        13 years ago, # ^ |
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        it would have been WA anyway.
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13 years ago, # |
  Vote: I like it +1 Vote: I do not like it
Even I couldn't submit in the last couple of minutes. The site went unresponsive and I got some 502/504 error. It appeared with 30s left on the clock . I selected the file and clicked on submit and that request also timed out.
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13 years ago, # |
  Vote: I like it +3 Vote: I do not like it
I couldn't access the site in the last 5-6 minutes! Kept on giving me 504! Also, problem B? What was that? The question seemed fine, but the explanation of the test cases was just... weird!
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13 years ago, # |
  Vote: I like it +3 Vote: I do not like it
I couldn't submit at the very last moment... after fixing the stupid bug of D... and the problem description was horrible to understand.....
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13 years ago, # |
  Vote: I like it -17 Vote: I do not like it
It is a very bad contest.
Each problem has 40-50 lines
And for me to translate the questions is very hard during the contest.
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13 years ago, # |
  Vote: I like it +3 Vote: I do not like it
I liked the contest, though problem B was exceptionally weird. Also, during last one minute I wasn't able to open solutions for hacking.
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    13 years ago, # ^ |
      Vote: I like it +1 Vote: I do not like it
    Why do you think problem B is weird?
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      13 years ago, # ^ |
        Vote: I like it +1 Vote: I do not like it
      A single sentence had several conditions. The conditions should be broken down in form of points, so that they are readable and understandable.
      Aim of the problem statement should be to explain the problem to the participant not confuse him.

      PS: I got 3 WA's on C, because I missed the following line "If a line has less than k vowels, then such line can't rhyme with any other line". It was written separately from other conditions.
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13 years ago, # |
  Vote: I like it +3 Vote: I do not like it
I was stuck in Problem A due to a little bug that crept in...  I turned it to a problem:

Look at the following C++ function that is supposed to return the position of k-th vowel from the right of nonempty string s if the number of the vowels does not exceed k, or string::npos otherwise.

size_t kth_vowel(const string& s, int k) {
  assert(s.size());
  size_t pos = s.size();
  for (int i = 0; i < k; ++i) {
    --pos;
    pos = s.find_last_of("aeiou", pos);
    if (pos == string::npos) return pos;
  }
  return pos;
}
Is this code correct?  If not, why?

Answer: when s has k - 1 vowels and (k - 1)-th vowel is at the beginning of s, this function does not return string::npos though it should.
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13 years ago, # |
  Vote: I like it 0 Vote: I do not like it
Hello,

would it be possible to upload somewhere test no 37 (problem C div 2)?

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

    this is test kind of this:

    2 1
    a
    bi
    bi
    a
    a
    a
    a
    a

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      13 years ago, # ^ |
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      Ah, of course, thanks.
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      13 years ago, # ^ |
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      Thanks.
      I have a wrong answer on test 39, too
      Thank you very much.
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13 years ago, # |
  Vote: I like it 0 Vote: I do not like it
What was the intended solution for E? It seems like everyone timed out on case 27.
I had O(NK log K) where the K log K came from just a single sort--seemed like it should be efficient enough.
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    13 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    It can be solved in O(NK).
    I already wrote the editorial in Russian, and soon wiil translate it in English (if someone doesn't do that earlier).
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13 years ago, # |
  Vote: I like it +1 Vote: I do not like it
Although the statement for problem B was understandable and I solved it correctly, It was not easy to comprehend all the conditions at once (may be my mind is slow).
[The joins must be vertical and you cannot rotate. ]
A figure could have made the statements better.

And Is the match rated ?( as lots of people cannot submit in the last moment.)

Don't make it as "vote if you want it to be rated" .
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    13 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    Ratings have been updated already.
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    13 years ago, # ^ |
      Vote: I like it +5 Vote: I do not like it
    actually I can't understand problem B very well,the statement is quite complex.
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      13 years ago, # ^ |
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      Yes, It gives advantage to people knowing Russian.
      May be we sud start learning it.
      (It is the only contest being held in multiple languages)
      (May be some day, it follows ICPC style or Topcoder style and make a single language contest, that way , nobody will get unfair language advantage.)
      (Maybe its only my concern)
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13 years ago, # |
  Vote: I like it -7 Vote: I do not like it
First Contest to use google translate more than eclipse :)
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13 years ago, # |
  Vote: I like it +15 Vote: I do not like it
Very nice contest. Thank you, Endagorion . I am blue for first time :)
Merry Christmas everyone :)
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13 years ago, # |
  Vote: I like it +4 Vote: I do not like it
Merry Christmas!!!
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13 years ago, # |
  Vote: I like it +5 Vote: I do not like it
The problem statement for problem B Div. 2 was very weird. I had the right solution but didn't submit it thinking there might be some extra conditions. Finally submitted and got WA ! Checked the test cases after contest and submitted my original one ! Accepted ! 
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    13 years ago, # ^ |
    ← Rev. 2   Vote: I like it +6 Vote: I do not like it

    Yes, I agree that this problem's difficulty is a bit too high for B div 2 (because of the statement). But anyway, I don't understand, why many people couldn't solve it. The comments to the example help very much. My first attempt got RE4 (because of division by zero), but it's pretty easy to see the source of it.

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    13 years ago, # ^ |
      Vote: I like it +1 Vote: I do not like it
    I have no idea what are you talking about, you submitted 3 times always with different source code:
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13 years ago, # |
  Vote: I like it +4 Vote: I do not like it
how to get the complete testcase ?
i failed in 37th testcase for problem 3 in div2..

on checking my submissions i am only able to see the small part of the testcase...
how to get the complete testcase ?
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    13 years ago, # ^ |
      Vote: I like it +5 Vote: I do not like it
    try that:
    2 1
    a
    bi
    bi
    a
    a
    a
    a
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      13 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it
      yeps you are correct...
      i forgot to include this scenerio... thnks a lot...

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        13 years ago, # ^ |
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        I forgot that during the contest, too.
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13 years ago, # |
  Vote: I like it +12 Vote: I do not like it
Although I have already accepted problem B div2 ... I still don't fully understand it :D
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13 years ago, # |
  Vote: I like it +5 Vote: I do not like it
In practice, what does the strange time 596523:14 mean?
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13 years ago, # |
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Thanks codeforces for everything!

But please have some graph problems in future contests!

Thanks, Happy new year!
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