Ripatti's blog

Codeforces Beta Round #81
By Ripatti, 13 years ago, translation, In English

Hello everyone!

I am the author of problems of today round. RAD, Connector, it4.kp helped me to prepere this contest. Delinur thanslated statements into english.

It will be a thematic contest. And the theme is Disgaea.

Is it possible to survive artef damage that is written by nine-digit number?
Of course, if amount of your health points is ten-digit number.
fans about Disgaea

Disgaea: Hour of Darkness is tactical RPG video game for consoles Playstation 2, PSP и Nintendo DS. So, get acquainted:

Etna, Laharl and Flonne - main characters of the game

The problems involves some aspects of the game mechanics. They are adapted for problems, therefore a bit different from original ones. Please use statements as formal documents.

Some problems have animated pictures. Please ensure that your browser supperts formats APNG or GIF.

Problem points will be standard for contests of Codeforces:
500-1000-1500-2000-2500.

Good luck!

UPD. The contest ended and ratings was recalculated.
:Winners:
1. KADR
2. neal
3. cerealguy
4. ivan.popelyshev
5. tourist

Editorial.
Announcement of Codeforces Beta Round 81
  • Vote: I like it
  • -7
  • Vote: I do not like it

Comments Comments (175)
| Write comment?
13 years ago, # |
  Vote: I like it 0 Vote: I do not like it
Good luck to all!!!
High ratings and rankings
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  • 13 years ago, # ^ |
      Vote: I like it -11 Vote: I do not like it
    I don't undrstand why am i getting negatives.....Some people are not even that generous
    → Reply
13 years ago, # |
  Vote: I like it +12 Vote: I do not like it
Chrome does not support APNG images with default settings. Will viewing those pictures be really essential to understand statements?
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  • 13 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    Codeforces does not support GIF, but APNG works. In the statement will be APNG picture and link to separated GIF-picture.
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  • 13 years ago, # ^ |
      Vote: I like it +6 Vote: I do not like it
    2 VArtem (I dot'n know why I cannot answer in that branch)
    Codeforces does not support GIF, but APNG works. In the statement will be APNG picture and link to separated GIF-picture.
    → Reply
    • 13 years ago, # ^ |
        Vote: I like it +1 Vote: I do not like it
      but, please, answer to VArtem: Will viewing those pictures be really essential to understand statements? 
      → Reply
      • 13 years ago, # ^ |
          Vote: I like it +16 Vote: I do not like it
        Yes.
        → Reply
        • 13 years ago, # ^ |
            Vote: I like it +16 Vote: I do not like it
          In this case, probably using these pictures was not the best decision
          → Reply
        • 13 years ago, # ^ |
            Vote: I like it +3 Vote: I do not like it
          Could you please tell the size of the animations? I have a ~15KB/s connection so I need to know if loading these pictures is fast enough for me.
          → Reply
          • 13 years ago, # ^ |
              Vote: I like it 0 Vote: I do not like it
            Sum of sizes less than 30KB. Don't panic, please)
            → Reply
            • 13 years ago, # ^ |
                Vote: I like it +1 Vote: I do not like it
              oh, this sounds good)
              and what's about the quality?
              → Reply
        • 13 years ago, # ^ |
            Vote: I like it 0 Vote: I do not like it
          it's very bad.
          as for me, I'm now in the Russian South, and using MTS-modem. The speed here is too bad to see animated images ( even text is loading too slow )...
          It seems like I won't be able to participate in this CFBR :(
          → Reply
          • 13 years ago, # ^ |
              Vote: I like it 0 Vote: I do not like it
            the main point is that u have internet connection and desire, but it's not enough right form this moment. it's really not good step from cf
            → Reply
            • 13 years ago, # ^ |
                Vote: I like it 0 Vote: I do not like it
              i don't blame anybody )
              but if the images are small, i'll participate in this round, ok! :)
              → Reply
        • 13 years ago, # ^ |
            Vote: I like it 0 Vote: I do not like it
          I guess flash is a good choice, as it's required by hacking
          → Reply
          • 13 years ago, # ^ |
              Vote: I like it 0 Vote: I do not like it
            Flash implementation for Linux makes my dual-core processor feels like 4040
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  • 13 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    And how can I enable APNG in Chrome?
    → Reply
13 years ago, # |
  Vote: I like it +43 Vote: I do not like it
APNG extension for Google Chrome
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13 years ago, # |
← Rev. 3   Vote: I like it -54 Vote: I do not like it

удачі всім. сподіваюся, що ви високий рейтинг
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  • 13 years ago, # ^ |
      Vote: I like it +18 Vote: I do not like it
    А почему Берляндия вне закона, а Hell еще нет ? о_О 
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13 years ago, # |
  Vote: I like it +13 Vote: I do not like it
This theme is awesome. Just saying.
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13 years ago, # |
  Vote: I like it +3 Vote: I do not like it
I hope that all things will not affect on system work.
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13 years ago, # |
  Vote: I like it +12 Vote: I do not like it
Animated pictures!! Is this going to be the 1st contest ever with animated images(which are relevant to problem-set) ?
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13 years ago, # |
  Vote: I like it +7 Vote: I do not like it
"Is it possible to survive artef damage that is written by nine-digit number?
Of course, if amount of your health points is ten-digit number.
fans about Disgaea"

What a crazy game! It makes me want to play.
By the way, I think the HP may overflow with a 32-bit int.

Good Luck All.
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13 years ago, # |
  Vote: I like it +40 Vote: I do not like it
Okay, cool. BUT NO LONG STORIES!
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13 years ago, # |
  Vote: I like it +1 Vote: I do not like it
Following the thematic, I will use the Best Browser No One Used, i.e., Opera, at least it supports APNG.
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13 years ago, # |
  Vote: I like it 0 Vote: I do not like it
Will it work in mozilla firefox
???
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13 years ago, # |
  Vote: I like it +2 Vote: I do not like it
Good luck to all !
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13 years ago, # |
← Rev. 2   Vote: I like it +14 Vote: I do not like it

Animations (If picture is static or not displayed then this format is not supported by your browser):

gif:[hidden]apng:
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  • 13 years ago, # ^ |
      Vote: I like it +4 Vote: I do not like it
    Damn. :(
    → Reply
  • 13 years ago, # ^ |
      Vote: I like it +5 Vote: I do not like it
    Can you tell me which browser is used in your computer.Thx!
    → Reply
    • 13 years ago, # ^ |
        Vote: I like it +1 Vote: I do not like it
      Opera 11 has no problems with displaying apng and gif pictures, as i see.
      → Reply
    • 13 years ago, # ^ |
        Vote: I like it +1 Vote: I do not like it
      Google chrome (last stable):
      apng - static
      GIF - OK
      Opera (last stable):
      both OK

      → Reply
13 years ago, # |
  Vote: I like it -6 Vote: I do not like it
It would be better if this round had div 2. :)

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13 years ago, # |
  Vote: I like it +9 Vote: I do not like it
Hope that the problem statements will be easy to understand :)
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  • 13 years ago, # ^ |
      Vote: I like it +3 Vote: I do not like it
    I don't think that hope was fulfilled...
    → Reply
13 years ago, # |
  Vote: I like it +202 Vote: I do not like it
Readforces...
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  • 13 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    Один коммент и его автор 217 по вкладу.
    → Reply
    • 13 years ago, # ^ |
        Vote: I like it +2 Vote: I do not like it
      Не очень понимаю, почему все так парятся по поводу вклада. А самое главное, что лидеры по вкладу о вкладе не парятся.
      → Reply
  • 13 years ago, # ^ |
      Vote: I like it +3 Vote: I do not like it
    Hackforces...
    → Reply
13 years ago, # |
  Vote: I like it +41 Vote: I do not like it
really lengthy problems ...a lot of inputs  lot of time wasted to understand the problems
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13 years ago, # |
  Vote: I like it +19 Vote: I do not like it
Isn't the animation too fast? I didn't understand much from it.

Extra long problem statements again. Nobody cares.

Excellent, excellent, make them longer next time and insert another animation with 100 pictures in second. That would be great.

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13 years ago, # |
  Vote: I like it +29 Vote: I do not like it
I don't like meaningless hacks on problem A and long statements＆ codes of problem C.
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  • 13 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    i agree with you...it was pathetic..and why div2 rating is not changed??
    → Reply
13 years ago, # |
  Vote: I like it +2 Vote: I do not like it
hack festival on problem A
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13 years ago, # |
  Vote: I like it +4 Vote: I do not like it
Bloody hacks on A!
Is there a way to see the input of successful hacks by someone?
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13 years ago, # |
  Vote: I like it +1 Vote: I do not like it
Anyone care to explain what the hacking fest on A was all about? I got my A hacked and still am clueless...

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

    you may add a eps to get the right ans when you change a real to int.
    → Reply
    • 13 years ago, # ^ |
        Vote: I like it +7 Vote: I do not like it
      Why is that necessary? I don't get it. Is it some internal trick that every coder should master?
      → Reply
      • 13 years ago, # ^ |
        ← Rev. 3   Vote: I like it +7 Vote: I do not like it

        9400*0.99=9306
        but in C:(int)(9400*0.99)=9305
        → Reply
        • 13 years ago, # ^ |
            Vote: I like it +2 Vote: I do not like it
          Using Windows+GCC got the right answer 9306. So maybe it is language-dependent and platform-dependent.
          → Reply
      • 13 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        Because you can get precision issues, then (int) 9.9999999576 becomes 9, not 10.

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

          I see. But the thing is, while I understand that there could exist such issues, I didn't know it would cause such an effect. How could I know it during contest time, or should is this quirk "what every computer science student should know"? I am slightly confused by this.

          Edit: Also, how could I know hoe large the correction should be? Thanks!
          → Reply
          • 13 years ago, # ^ |
              Vote: I like it +3 Vote: I do not like it
            Just a eps and everything will be OK...
            → Reply
          • 13 years ago, # ^ |
              Vote: I like it +2 Vote: I do not like it
            I agree.
            Hacking Problem A for this kind of test cases is meaningless.
            → Reply
          • 13 years ago, # ^ |
              Vote: I like it 0 Vote: I do not like it

            In fact, it's "something you should know." I doubt you will forget it from now on.

            And depends of the problem, in this case I don't think it was needed too much, maybe 0.00001 or something like that. I don't know a rule of thumb.

            → Reply
            • 13 years ago, # ^ |
                Vote: I like it 0 Vote: I do not like it
              The thing is, I do know. I read though most of the paper "What every computer scientist should know about floating-point arithmetic".

              However, when a rule of thumb is lacking, how could I know if I should, say, add or subtract, or how much too add? In my case, to avoid possible error caused by adding too much, consider the fact that this is problem A, I did not add the eps. I believe that with an error analysis, the correct eps could be calculated, but if that is needed, I doubt it will be a good problem A.

              Nevertheless, thank you for your answer. Good luck and have fun in the future! I would not call today's contest "fun", but it is a learning process, and valuable in this way.
              → Reply
              • 13 years ago, # ^ |
                  Vote: I like it 0 Vote: I do not like it

                No problem. In my case, at least, it's some kind of testing, you just think about what to do when you have a little less or a little more than the answer, so you make the comparison right.

                In UVa, for example, this is exploited a lot.

                → Reply
13 years ago, # |
  Vote: I like it +19 Vote: I do not like it
Do you feel the testing speed? Just wow.
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13 years ago, # |
← Rev. 3   Vote: I like it +8 Vote: I do not like it

crazy hack on Problem A...
"int (level * k + 1e-8)" for GNU C++
"8700 * 0.94" :P
"(int)100*0.94 == 93" for GNU C++
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  • 13 years ago, # ^ |
      Vote: I like it +8 Vote: I do not like it
    I guess the case "int(100*0.94) == 93" may be like this process:

             0.939999....
           _______________________
    100 )94
            900
            ____
             400
             300
             _____
             1000
               900
               _____
              1000
                900
                _____
               1000
               ... ...
    → Reply
13 years ago, # |
  Vote: I like it +2 Vote: I do not like it
just a precision problem of 0.00001 in problem a makes it a disaster........
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13 years ago, # |
  Vote: I like it +24 Vote: I do not like it
Overall, I don't like this contest...
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13 years ago, # |
  Vote: I like it +1 Vote: I do not like it
Strange .....the number of successful attempts to problem a reduced to one-fourth after the system testing(including me) terrible...!!Are the successful hacks involved in system testing???
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  • 13 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    yes successful hacks are included as part of system testing. But probably that is not the reason for so many sys test fails they probably had that case already in the test cases.
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    • 13 years ago, # ^ |
        Vote: I like it +4 Vote: I do not like it
      Last time I checked, that is not true.

      In fact, I asked, in the Codeforces Contest Rules page, to include these hacks in the system test.  So far, I have not received an answer from the admins.
      → Reply
13 years ago, # |
  Vote: I like it +18 Vote: I do not like it
This contest was really awful.
Lame problem statements with huge problem description.
It doesn't prove anything.

What are they trying to test? <Contestant's reading ability??? >

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  • 13 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    I agree with you.As a Chinese student,it is really hard for me to read so huge problem description.I don't think the contest purpose including train the contestant's reading ability. 
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13 years ago, # |
  Vote: I like it +42 Vote: I do not like it
I still don't understand problem D.
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  • 13 years ago, # ^ |
      Vote: I like it -8 Vote: I do not like it
    neal, what is the corner case did you use?
    → Reply
    • 13 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it
      37 main test ...
      400*0.29=116, not 115
      → Reply
      • 13 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it
        This one works, thanks. But is this exactly the case neal used?
        → Reply
        • 13 years ago, # ^ |
            Vote: I like it +8 Vote: I do not like it
          Yes, that's what I used. Here's the full case:

          20 3 0.29
          a 100
          b 200
          c 300
          d 400
          e 500
          f 600
          g 700
          h 800
          i 900
          j 1000
          k 1100
          l 1200
          m 1300
          n 1400
          o 1500
          p 1600
          q 1700
          r 1800
          s 1900
          t 2000
          z
          m
          k
          → Reply
          • 13 years ago, # ^ |
              Vote: I like it 0 Vote: I do not like it
            So in essence, it exploited 100 * 0.29 = 28(which is wrong). Thank you. 
            → Reply
          • 13 years ago, # ^ |
              Vote: I like it 0 Vote: I do not like it
            How did you come up with 0.29? 0.58 works as well. I've tried some small numbers by hand but to my disappointment all of them got rounded up. I couldn't figure out how to run a search which would avoid arithemtics and compiler optimizations associated with them.
            → Reply
            • 13 years ago, # ^ |
                Vote: I like it 0 Vote: I do not like it
              I've used exactly the same trick, i.e. 400*0.29 (my test case is #40). To find it I've ran a brute-force over all A and K and tried to round A*K with and without eps. If those two numbers are different, then there was a rounding error. The first such test case is 100 * 0.29, but 100* 0.29 is less than 100, which is not what we want. The next one is 400 * 0.29 and it is fine for us.
              → Reply
  • 13 years ago, # ^ |
    ← Rev. 2   Vote: I like it -6 Vote: I do not like it

    You have a n x m board, where each cell has a color. A cell might contain a pyramid, and each pyramid has a color, too.
    The procedure is something like this:
    You have an empty queue, you add the given pyramid (x, y) to the queue. Now pop a pyramid from the queue, let its color be A. If the cell the pyramid is standing on isn't transparent and its color B is different from A, then let S be the set of all cells with color B. Change the color of each cell in S to A and add all pyramids on these cells to the queue, removing them from the board completely (in spiral order considering current cell as center).
    It took me some time to get this problem, and I have a working solution to it. But I didn't submit it as a protest on the confusing problems :P
    → Reply
    • 13 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it
      Do you need a disjoint set data structure to solve this problem?
      → Reply
      • 13 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it
        I think I've seen someone using Disjoint Set to solve it, but my solution doesn't use it.
        → Reply
13 years ago, # |
  Vote: I like it +5 Vote: I do not like it
Great, I just finished taking my GRE again..
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13 years ago, # |
  Vote: I like it +1 Vote: I do not like it
I wonder in which programming language you don't have to consider the EPS thing but still get accepted on problem A?
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  • 13 years ago, # ^ |
      Vote: I like it +2 Vote: I do not like it
    In Python you can use Decimal type.
    → Reply
  • 13 years ago, # ^ |
    ← Rev. 2   Vote: I like it +3 Vote: I do not like it

    Any language: just consider k = k * 100, and all skills are multiplyed by 100 either.
    → Reply
    • 13 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it
      Yes, integer arithmetic is the safest.
      While using double precision, let EPS = 1eN, which value of N is enough? -8, -10, -11 or depend on the specific problem?
      → Reply
    • 13 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it
      I don't think this will work.
      Because, for example, floor(0.29 * 100) = 28
      → Reply
      • 13 years ago, # ^ |
          Vote: I like it +1 Vote: I do not like it
        When saying integer arithmetic, I mean the following code(got AC).
        char k[10];
        int K;
        scanf("%d%d%s",&n,&m,&k);
        K = (k[2] - '0') * 10 + (k[3] - '0');
        for (i = 0; i < n; ++i) {
                cin >> name >> level;
                if (level * K >= 10000) skill[name] = level * K / 100;
        }
        → Reply
        • 13 years ago, # ^ |
            Vote: I like it 0 Vote: I do not like it
          Yes, this works, but you are manually constructing integer from string. I don't think LastDay in the comment 51579 (to which I replied) meant this (at least I can't see this in the comment).
          → Reply
        • 13 years ago, # ^ |
            Vote: I like it 0 Vote: I do not like it
          scanf("%d %d 0.%d",...) мне кажется должно работать
          → Reply
      • 13 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it
        you just let k = k * 100 + 0.5;that works~
        → Reply
        • 13 years ago, # ^ |
            Vote: I like it 0 Vote: I do not like it
          The question was without "EPS thing", and 0.5 is kind of EPS here.


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

in java if we have k as float instead of double it would pass the hacks... too bad I had it as double too.
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13 years ago, # |
  Vote: I like it +10 Vote: I do not like it
The statements are too long ...
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13 years ago, # |
  Vote: I like it +12 Vote: I do not like it
how much after the contest new ratings come?
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13 years ago, # |
  Vote: I like it 0 Vote: I do not like it
In problem A I found difference in English & Russian statement.
In Russian statement it explicitly said after multiplying with k , if less than 100 it should be forgotten
but in English statement this was missing <didn't say anything about before or after >.
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  • 13 years ago, # ^ |
      Vote: I like it +4 Vote: I do not like it
    I have problems with this too, i didn't know if it was before or after multiplying by k.

    The test example had megafire 120, and in the result it has megafire 0, so that's why i assumed that it was after, but i agree that this part was somewhat bad specified.
    → Reply
  • 13 years ago, # ^ |
    ← Rev. 2   Vote: I like it 0 Vote: I do not like it

    I agree too, but if you check the sample test you'll notice that the output is only possible if after multiplication the skill is below 100.

    edit: I didn't see that victor.juquila had posted sry
    → Reply
13 years ago, # |
← Rev. 2   Vote: I like it +10 Vote: I do not like it

Solving the problem was depended on coding  experience and not on "algo" knowing or sharp "thinking". Sometimes skills of reading realizing and coding fast is more important. That's what i think  the author wanted to tell. Thanks for the round.
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  • 13 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    Excellent, excellent, make them longer next time and insert another animation with 100 pictures in second. That would be great. --by coder
    → Reply
13 years ago, # |
  Vote: I like it 0 Vote: I do not like it
Even Google translator can translate Russian statements better than today's English statements.
Why do we have to open the same problem in Russian statement to verify if what we are thinking is correct?


→ Reply
  • 13 years ago, # ^ |
      Vote: I like it +18 Vote: I do not like it
    Sorry man, I don't believe you.
    → Reply
    • 13 years ago, # ^ |
        Vote: I like it +1 Vote: I do not like it
      If you don't believe me then read problem A in both Languages.
      You will surely find differences.
      → Reply
      • 13 years ago, # ^ |
          Vote: I like it +4 Vote: I do not like it
        I used Google translate, and I think shakil is correct.  In the Russian version, the problem statement uses the term "degree of knowledge" to specify the skill level after multiplying by k, and then uses this term again when it specifies that the "degree of knowledge" must be >= 100.  In the English version, it only uses the word "skill", so it doesn't differentiate between the two numbers, before and after.
        → Reply
13 years ago, # |
  Vote: I like it 0 Vote: I do not like it
Why the rates didn't get updated yet?
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13 years ago, # |
  Vote: I like it +1 Vote: I do not like it
Massive Disaster...........
One precision problem of 1e-9(.000000001) don't need to highlight with a massive cost .........

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13 years ago, # |
← Rev. 2   Vote: I like it -12 Vote: I do not like it

I think the contest should be unrated (or at least for division 2). Hardening the problems with huge problem description is meaningless.
After a lot of try i couldn't understand problem B.
sorry for my bad english
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  • 13 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    I also spent much time to understand it.
    → Reply
  • 13 years ago, # ^ |
    ← Rev. 4   Vote: I like it 0 Vote: I do not like it

    Hope the calculation detail would be helpful.
    //case 2
    (1 - ((0.2 * 0.1 * 0.3 * 0.3) + (0.2 * 0.1 * 0.7 * 0.7) + (0.1 * 0.3 * 0.7 * 0.8) + (0.2 * 0.3 * 0.7 * 0.9) + (0.2 * 0.1 * 0.3 * 0.7))) /* at least two other senators vote for the player except the fifth senator, under these situations, thus strictly more than half senators vote for the player, fighting is unnecessary */
     + (0.2 * 0.1 * 0.3 * 0.3 * (100 / 148)) + (0.2 * 0.1 * 0.7 * 0.7 * (100 / 205)) + (0.1 * 0.3 * 0.7 * 0.8 * (100 / 217)) + (0.2 * 0.3 * 0.7 * 0.9 * (100 / 214)) + (0.2 * 0.1 * 0.3 * 0.7 * (100 / 228)) = 0.9628442962 /* only one or even no one vote for the player except  the fifth senator, under each situation, you could compute the success probability of fighting using A/(A+B) formula */
    //case 3
    0.5+0.5*(20/40) = 0.75
    → Reply
13 years ago, # |
← Rev. 2   Vote: I like it -6 Vote: I do not like it

EDIT: no, they aren't rejudging solutions
→ Reply
13 years ago, # |
  Vote: I like it -9 Vote: I do not like it
Authors ... Next time use a CODER to translet  Russian To English....or just don't translet...
We will make our way in our own step ..........Just don't make a awful Translation..... 
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  • 13 years ago, # ^ |
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    They spent their time and energy to make the problem the translate them.  Yes , the job is not perfect . But we should not criticize them like you did. 
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  • 13 years ago, # ^ |
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    I think the translation was smooth and good most of the time. 
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13 years ago, # |
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When will the ratings be updated?
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  • 13 years ago, # ^ |
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    Some of the ratings are updated while some are not. Why?
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13 years ago, # |
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Places in profiles does not match with real places.
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  • 13 years ago, # ^ |
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    may be it's places in division?
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  • 13 years ago, # ^ |
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    It's seems like for Div2 contest was unrated, and they were skiped at rerating
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    • 13 years ago, # ^ |
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      it's just not fair.. it was not said before the contest that only Div1 would be rated :/
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13 years ago, # |
  Vote: I like it +75 Vote: I do not like it
Disgaea: Hour of Darkness

Actually, two hours of Darkness.
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13 years ago, # |
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Read Problem A 3-4 times to get the actual meaning... But all that became useless I failed on A and B as well.
Hoping direct problems in nxt Beta round. :'-(


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  • 13 years ago, # ^ |
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    In fact,I think the translation of description is not good for a lot of Beta Rounds.
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13 years ago, # |
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Can anyone explain Problem B?
I am having hard time understanding sample input /output. 
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  • 13 years ago, # ^ |
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    Point us the specific part of test case where you are facing problem. It will be very hard to re-write the problem statement again in our own words.Between I think problem statement for B is very clear.
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13 years ago, # |
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Are ratings updated only for Div1?
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13 years ago, # |
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no offense to the organizers, but today was painful.
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13 years ago, # |
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@Ripatti, thank you for the contest. Although people have something to say :-)
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13 years ago, # |
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why div2's ratings updated so slowly...  >.<
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  • 13 years ago, # ^ |
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    Do you know at least one div2 participant whose rating is updated? I know a div1 participant whose rating is not updated, namely Commandos.
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13 years ago, # |
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the rating update only for div1? why, it's unfair.

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13 years ago, # |
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:(
my submited code contian
int val=ni[indx]*k;  //failed system test
after the contest
int val=ni[indx]*k  +(1e-10); //passed system test.
just for accuracy
but thanks to allah :) 
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  • 13 years ago, # ^ |
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    yeah, indeed 1e-8 is enough~
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  • 13 years ago, # ^ |
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    You are not the only one with this problem.
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  • 13 years ago, # ^ |
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    Specifically in problem A, the number k will always be given in the form 0.xx, where 'xx' has exact 2 digits. So one can read 'xx' as an integer and test (ni[indx]*xx)/100 as an integer division. This also solves problems of accuracy.
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13 years ago, # |
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why nothing mentioned while registering about rank updating? were previous beta rounds (not only ones) the same?
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13 years ago, # |
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In problem C, my after-contest submission#609640 gets a WA on test#8. The log says: "wrong answer too many empty slots in equipment items". Could someone provide me with that test case please?

Also, may any of the admins let us know why did the rating updates pause suddenly?
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  • 13 years ago, # ^ |
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    It means that the three items in the output of your program must contain more residents.
    Or, equivalently, that there are too many remaining residents for the items that were not chosen.
    The problem statement says "We cannot remove a resident from the items and leave outside".
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13 years ago, # |
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Thanks for your reply, but why would my output of the same submission be correct for case#1 (you will notice that 'bobby' is totally ignored in the output).
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  • 13 years ago, # ^ |
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    In case #1, indeed 'bobby' may or may not be in the output, because there is room both in the third item 'iceorb' or in the fourth item 'longbow' that was not taken.

    But if you there are, say, three useless residents and only two slots available in the not chosen items, then you must put some of them in the output.
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    • 13 years ago, # ^ |
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      Oh I see now :) thanks again for the clarification.
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13 years ago, # |
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Due to technical reasons rating for participants of the Division 2 was not updated. Soon we will fix that and update ratings for all participants.
===
Из-за технических накладок рейтинг для участников второго дивизиона пересчитан не был. Скоро мы все поправим и сделаем пересчет для всех.
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  • 13 years ago, # ^ |
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    Ratings are updated. Sorry for delay.
    ===
    Рейтинг пересчитан. Приносим извинения за задержку.
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13 years ago, # |
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This English is too long for me....
The theme is good,but too complicated theme makes a contest bad.
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13 years ago, # |
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My rating is yet to be recalculated. The blog entry says that the ratings are recalculated. Am I missing something?
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13 years ago, # |
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I sucked at this contest.  Problem A was some kind of tricky. I don't want my rating to be recalculated :(
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13 years ago, # |
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Overall,I don't complain the problem.I just want to say,I still have a lot of things to learn.....
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13 years ago, # |
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神馬時候更新蕋甼！
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13 years ago, # |
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Can any one help me to understand why very simple brute force solution for B is getting AC. I expected the complexity to be around 9^8 * 256 which is nearly 10^10 for very simple case (n=8, k=8, A=1000, rest n lines are 0 0). I was amazed to see that solution runs on my system and codeforces machine within 2sec. For reference anyone can view my solution which implements brute force strategy. There are no. of other solution too using the same method.
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  • 13 years ago, # ^ |
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    forget it please. I found the answer :) . Thanks
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  • 13 years ago, # ^ |
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    9^8 is too large. It is around 8H8 = 15C7 = 6435 because the player can give at most 8 sweets in all (not for each).
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13 years ago, # |
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forget it please. I found the answer :) . Thanks
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13 years ago, # |
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For problem A, is K in format ".01" or ".99" a valid input?
i think many solutions using somthing like (str[2] - '0') * 10 + (str[3]-'0') will be down...
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  • 13 years ago, # ^ |
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    No, I have asked about it. The data ensures that the format string "%d %d 0.%d" reads data correctly.
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    • 13 years ago, # ^ |
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      just in case ... scanf("%d%d%*[^.].%d",&a,&b,&c);
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13 years ago, # |
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Good job, writers!  I enjoyed long problem statements and the very educational trap in the problem A.  I'll never ever forget about floating-point precision matters!
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13 years ago, # |
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No editorial yeT..!! :(
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  • 13 years ago, # ^ |
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    There's something in the authors' blog.
    http://www.codeforces.com/blog/entry/2462
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