Блог пользователя Gassa

Автор Gassa, история, 6 лет назад, По-русски

Всем привет!

Приглашаю вас поучаствовать в Codeforces Marathon Round 2. Это соревнование начнётся во вторник, 24 июля 2018 года в 15:00 MSK, и продлится 7 дней. В соревновании будет одна задача, основанная на механике пары детских настольных игр. Скорее всего, задача не имеет быстрого полного решения. Так что решения будут оцениваться баллами, и победит тот, кто наберёт больше всего баллов.

Соревнование будет нерейтинговым, поскольку задача существенно отличается от задач рейтинговых раундов.

В основное время решения будут тестироваться на примерах и на предварительных тестах. После окончания итоговое решение каждого участника будет перетестировано на итоговом наборе тестов, и баллы в этом тестировании определят итоговую таблицу результатов. Соревнование пройдёт на платформе Codeforces при поддержке кружка обучения мастерству программирования при СПбГУ и 90.01 Group.

На Codeforces пока проведено не так уж много марафонов. Так что, если что-то сломается — не расстраивайтесь, а напишите об этом, мы постараемся всё исправить.

Успехов в соревновании!

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6 лет назад, # |
  Проголосовать: нравится +37 Проголосовать: не нравится

Will it be allowed to participate in teams of 2 or more?

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    6 лет назад, # ^ |
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    As seen in registration option, I think they wont allow.

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      6 лет назад, # ^ |
      Rev. 2   Проголосовать: нравится 0 Проголосовать: не нравится

      But in previous Marathon Round participation in team was allowed. If this can be done in this round as well? Anyways it is unrated.

      Edit — Registration page allows team participation. It is just that it is not mentioned in announcement page.

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    6 лет назад, # ^ |
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    It is now possible to register either individually or in teams of 2 people.

    If you registered individually but now want to register as a team, you will have to find your previous registration and cancel it first.

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6 лет назад, # |
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Will hacking be there?

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6 лет назад, # |
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where I can see previous codeforces marathon contest?

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6 лет назад, # |
  Проголосовать: нравится +46 Проголосовать: не нравится

Gassa, Will there be T-Shirt distribution just like Codeforces Marathon Round-1 ?

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6 лет назад, # |
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So there is only one problem in the whole contest? Sounds challenging.

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6 лет назад, # |
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Can someone please explain in a little more depth how exactly these problems differ from normal rated rounds? I would like to participate, and have not taken a round like this before.

Thanks :)

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    6 лет назад, # ^ |
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    See I'll try to explain hope you understand. :) There will be one question only and there is no fixed answer for it! It may vary, its a problem where you are given some data and you have to write a program which uses this data to give the best possible output lets say this output as your final score! Now different programs/algorithms will produce different final scores and based on this final score produced by your program you will get a points for your algorithm! so the better your program works the more points you will get and thus better rank!

    hope it is clear!

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      6 лет назад, # ^ |
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      So, basically its like the challenge problem of codechef long challenge?

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6 лет назад, # |
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Has the beginning time changed(+30 mins) ?

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    6 лет назад, # ^ |
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    I think so. The start time has changed few minutes ago. Maybe something went wrong.

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    6 лет назад, # ^ |
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    Yeah, some last-minute problem occurred. Everything seems fine now. Sorry for the delay!

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6 лет назад, # |
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Can someone told me that why the match delayed 35 minutes?

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6 лет назад, # |
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Can someone tell me why the match delayed?

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6 лет назад, # |
  Проголосовать: нравится +5 Проголосовать: не нравится

I know it's unlikely, but what will happen if a bottle of color c is thrown and there is no more squares of this color exists in the rest of the stripe?

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    6 лет назад, # ^ |
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    Since the stripe is infinite and periodic, that would mean there is no such color in the pattern.

    Such tests are not explicitly forbidden. Still, it would be a miracle if this happens when we pick a test uniformly at random. If the miracle does indeed happen, we'll think of something.

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6 лет назад, # |
Rev. 2   Проголосовать: нравится 0 Проголосовать: не нравится

Проблемы со статусом. Иногда не показывает последние отправленные решении.

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6 лет назад, # |
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How many people will get T-shirt?

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6 лет назад, # |
Rev. 2   Проголосовать: нравится -168 Проголосовать: не нравится

It looks a bit suspicious

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    6 лет назад, # ^ |
    Rev. 3   Проголосовать: нравится +266 Проголосовать: не нравится

    Please do NOT suspect that.

    We, Japanese participants, love marathon contests and have a lot of experience. See this. https://community.topcoder.com/longcontest/stats/?module=CountryRank

    There are many marathon and game AI contests in Japan. We are just getting used to them. Also, keep in mind skill-set for marathon is a bit different from one for ICPC. For example, hakomo is a red coder on Topcoder marathon matches.

    We know sportsmanship is the most important. We never share code, knowledge or observation during contests. I guarantee.

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    6 лет назад, # ^ |
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    I'm wondering why there are too many downvotes to this comment. Of course I think there is no cheating, but also I feel that the suspicion itself was natural if you didn't know about marathon matches.

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      6 лет назад, # ^ |
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      I think downvoting is justifiable. Yes having a suspicion of cheating is natural, but casting this suspicion without evidence is simply irritating.

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      6 лет назад, # ^ |
      Rev. 2   Проголосовать: нравится +25 Проголосовать: не нравится

      I agree on kobae964's opinion.

      This is just a problem of the manner. Nobody blames you feel something is suspicious. I also think the leader board is different from usual contests and the combination of the country distribution and no very high SRM ratings makes it unusual. However, when you say something which could be rude if your opinion is wrong, you need to be careful to post it.

      Which point was problematic? — He just pasted a screenshot saying nothing but "it's a bit suspicious". To me, it was just like he gave a seed of gossip a bit lacking respect to the competitors rather than raising an issue. That's because you don't need to use negative sentences if you really want to know the reason for some unusualness. I prefer positive sentences + reasons.

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        6 лет назад, # ^ |
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        I really don't understand which positive sentence would you like to see. Maybe: "Look, what a funny coincidence, all these guys in the top of the scoreboard are from the same country and have a not high rating in the regular contests. Well done! Keep it up!" Any message of this kind would be fucking hypocrisy, do not you think?

        My message was absolutely neutral as it describes the natural feeling, and it really has no a direct charge of cheating, and I did not want to blame anyone. Btw, I suspected more that you had some similar task in the local competition than they are cheating. Maybe you'd rather like the words "strange" or "unusual" (as you wrote in your comment) over "suspicious" in my sentence, but in my vision that doesn`t change the idea of the message at all. Sorry if that was rude for you.

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          6 лет назад, # ^ |
            Проголосовать: нравится +17 Проголосовать: не нравится

          Thanks for replying.

          ... Any message of this kind would be fucking hypocrisy, do not you think?

          Of course, what you wrote is definitely not what I would’ve liked to see. It's like playing with sarcastic words.

          Btw, I suspected more that you had some similar task in the local competition than they are cheating.

          Actually, this is exactly what I would’ve liked to see. I think the reason brings a constructive discussion on the right track you intended. I understand your intent now and I'm sorry for misunderstanding. I've failed to guess your thought and I've supposed you were thinking those competitors were possibly cheaters.

          Now I realized I would've liked you to put the explicit reason why you felt so in order not to make someone like me misunderstand you, and "avoid" negative words if unnecessary. I think something like the following sentence doesn't have so many different interpretations: "I see many competitors from the same country on the leader board. Was there any similar competition before in their country?"

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6 лет назад, # |
Rev. 2   Проголосовать: нравится +26 Проголосовать: не нравится

Gassa Thank you a lot for the round, really nice task.

May someone share ideas of your solution? :)

My final submit: https://gist.github.com/yarrr-ru/97361c5bca72bb3b5f0e549b811a510b

I'll describe my key ideas soon, sorry.

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    6 лет назад, # ^ |
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    Thanks! I've noted my (rather simple) ideas here, and encourage the contestants to do the same with theirs!

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    6 лет назад, # ^ |
    Rev. 6   Проголосовать: нравится +18 Проголосовать: не нравится

    I have in general similar to your solution, but new states are generated in a different way. I take several moves from the current state, that are the best by distance, and to get the score of new states I perform ~30 more greedy moves, and only then calculate score as a weighted sum of positions. That is 38900 if all moves are performed with only the last unit. But in last 10 minutes of the contest I thought: "What if it's not optimal to perform all the moves with the last unit?", so I added some hacks, and got +1000 points. Unfortunately, after that there was no time for adjusting the constants for the new algorithm and for TL. So it's 39900 in scoreboard, about 40900 after some local fixes, and 42000 with increased constants and 4xTL. Code (for 40900): https://www.ideone.com/UXF5B4

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6 лет назад, # |
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Is there a way to change which submission will be judge now? I forgot to resubmit the best one after some teste Q.Q

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    6 лет назад, # ^ |
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    Sorry, this process is automated.

    The alternatives are currently not feasible: the best solution on pretests (as opposed to the last one with positive score) might actually be just lucky with them, and there is no additional functionality for the user to mark which solution to judge.