rng_58's blog

CODE FESTIVAL 2016 Qualification Round A
By rng_58, history, 8 years ago, In English

CODE FESTIVAL 2016 Qualification Round A will be held on Saturday (time). The writer is sugim48.

Contest Link

Contest Announcement

This is one of the three qualification rounds of CODE FESTIVAL. Top 10 foreign students of this round will qualify. If you are eligible for the onsite contest, please don't forget to fill the form at https://krs.bz/rhd-itm/m/code_fes_2016. Please check the detail of the tournament at http://codeforces.me/blog/entry/46647.

The contest duration is 2 hours, and there will be 5 problems. The first 4 problems are mainly used for choosing domestic students and much easier than other tournament competitions. However, we added one more problem and we hope this is interesting enough for choosing top 10 qualifiers. (Anyway, most probably the qualifiers will be determined by the speed of solving all problems). Note that there is no time penalty for incorrect submissions. The time penalty is MAX, not SUM.

The point values are 100 — 200 — 400 — 800 — 1200. If you are unfamiliar with AtCoder System, 2X-point problem in AtCoder is as hard as TopCoder's d1 X-point problem.

Let's discuss problems after the contest.

UPD: Congratulations to tourist, Endagorion, LHiC, Arterm, Kostroma, mmaxio, Um_nik, ainu7, malcolm, FatalEagle! (I don't know who is eligible and this is not the official information, please let me know if some of them won't come.)

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

Comments Comments (30)
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8 years ago, # |
  Vote: I like it +68 Vote: I do not like it

If you are sure that top-scorers will actually be sorted by speed of solving all problems, why don't you add harder problem (or even several problems)? I think that contests where lots of people have a full score usually make people unhappy, especially those who actually solved all problems but did it slower than the others. Of course, fast coding without bugs is also an important thing, but I believe that the good contest tests your skill of solving problems in the first place, and only after that, your skill of coding.

Will the same situation happen on the two remaining qualification rounds?

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    8 years ago, # ^ |
      Vote: I like it +38 Vote: I do not like it

    I agree that ideally the problems should be harder. However, we have budgets for only one extra problem for each round, and in order to avoid the worst situation where qualifiers are determined by the speed of first four problems, the last problem have to be on the safer (easier) side. Also, this is the first international contest for us and we are not sure about the number of strong participants.

    We carefully chose the last problem such that it tests your thinking speed rather than coding speed. Even if you fail in one of the rounds, you still have two more rounds and I'm sure strong people like you will qualify with high probability.

    Yes, the same situation will happen for all rounds, we've already decided all problems and the difficulties are about the same.

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

reminder (3 hours)

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8 years ago, # |
  Vote: I like it +15 Vote: I do not like it

Sorry but can you remind me if we need to get to top 10 or 100 to advance to finals, since in the website it's said that "Place of residence is irrelevant." for top 100 (does it include non-japanese students?)

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    8 years ago, # ^ |
      Vote: I like it +28 Vote: I do not like it

    Top 10. (Where did you find top 100?)

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

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

        Sorry, this is a mistake (it seems this is directly translated from Japanese version). Top 10, 5, 5 for A, B, C is the correct number.

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8 years ago, # |
← Rev. 2   Vote: I like it +28 Vote: I do not like it

rng_58 why is your name not there in the "top rated" list ?

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    8 years ago, # ^ |
      Vote: I like it +34 Vote: I do not like it

    Hmm, it seems I'm inactive. Recently I'm not diligent enough to compete in 1:35-3:35 AM matches, but I'll try some earlier matches.

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

I registered but can't see the tasks.

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

That's my third time when i submitted and got -1 for just reading from file.Can you make a feature that doesn't judge the solution if it doesn't pass the samples please?

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

    There's no penalty for WA in this contest anyway.

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      8 years ago, # ^ |
      ← Rev. 5   Vote: I like it 0 Vote: I do not like it

      I have RE,i mean making the feature in all other contests in future.

      UPD. Now i got it,i thought that there is no penalty only for WA.

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

        "Note that there is no time penalty for incorrect submissions. "

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8 years ago, # |
← Rev. 2   Vote: I like it +34 Vote: I do not like it

Duh.
>woke up at 5AM
>solved all problems with 48 minutes to go
>still far away from qualifying

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8 years ago, # |
  Vote: I like it +47 Vote: I do not like it


:D

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8 years ago, # |
  Vote: I like it +26 Vote: I do not like it
  • Need to solve all the problems very fast
  • No penalty for WA
  • Still testing locally on all the samples. What is wrong with me?
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    8 years ago, # ^ |
      Vote: I like it +13 Vote: I do not like it

    I also did this. If you have some mistake that can be caught by sample, testing locally probably makes you know about it much faster. However judge was pretty fast today, so difference wouldn't be big. However automatically generating own tests locally (unless you are in a desperate need of having countertest) would be pretty unnecessary :p.

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8 years ago, # |
← Rev. 2   Vote: I like it +38 Vote: I do not like it

My solution for problem D works for O(n2). Here is the code:

http://pastebin.com/4MCWYCw1

If all numbers are on the same line, my dfs performs n2 operations and works for 76s locally. However, this solution passed.

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

Those who are getting WA on D, check out this case.

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

    Whoah, I completely didn't think about interactions between different components. Fortunately my code is still ok :P.

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

    I can't understand what you want to explain by this picture. we can change it as follow:

      0 1 1 0
 ┌─┬─┬─┬─┐
1│1│2│ │ │
 ├─┼─┼─┼─┤
0│ │1│ │ │
 ├─┼─┼─┼─┤
0│ │ │1│ │
 ├─┼─┼─┼─┤
1│ │ │2│1│
 └─┴─┴─┴─┘
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      8 years ago, # ^ |
        Vote: I like it +8 Vote: I do not like it

      That is the correct answer. The image explains if you use DFS to determine each row / column's value and judge if every cell's value are non-negative by adding minimal value of rows and that of columns, it fails on this case.

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

        OK. It must be so sad that getting WA due to do such an unnecessary and wrong thing...

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