I_love_Tanya_Romanova's blog

By I_love_Tanya_Romanova, 4 years ago, translation, In English,

Hello everyone!

I want to invite you to participate in June Clash at HackerEarth. Contest is scheduled on June, 20. Contest duration is 24 hours, so there should be some comfortable time for every timezone :)

There will be five tasks in a problemset. Four of them are standard algorithmic problems with partial solutions allowed — you get points for every test that your solution passed. And the last task is an approximate problem — your score for this task depends on how good your solution is comparing to current best solution.

shef_2318 is author of this problemset. He already prepared January Lunchtime 2015 and a few interesting problems for CodeChef Long contests, and also he was both author of April Clash and co-author of May Clash.

I was working on this contest as a tester. As usual, I would like to say that I find this problemset interesting, I hope that some problems will be not too hard for beginners (don't give up and show your best with partial scoring) and some other tasks are challenging enough to attract more experienced contestants. I was glad to work with shef_2318 again :) Also I want to thank to chandan111 for technical help and doing his best on fixing all issues and improving HackerEarth platform.

There will be quite a lot of different contests over the weekend, and besides interesting problems, I have another reason for you to participate in this one:

Top5 of leaderboard will also receive some nice prizes:

  1. $100 Amazon gift card + HackerEarth T-shirt
  2. $80 Amazon gift card + HackerEarth T-shirt
  3. $50 Amazon gift card + HackerEarth T-shirt
  4. HackerEarth T-shirt
  5. HackerEarth T-shirt

I hope everything will run smoothly this time. Good luck to everybody — I hope to see you at the scoreboard :)

Upd. Contest has ended :) Thanks to everyone for participating :) Congratulations to winners:

1) kutengine

2) FatalEagle

3) anta

4) SoMin Mun

5) Kmcode

 
 
 
 
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4 years ago, # |
Rev. 2   Vote: I like it -19 Vote: I do not like it

Could you schedule it on Sunday? As you might know, there is the IPSC on Saturday.

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

What are some ideas that can be applied to the approximation problem? I tried a lot but nothing get high points

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    4 years ago, # ^ |
    Rev. 2   Vote: I like it +11 Vote: I do not like it

    You may check codes of other contestants now. Also I hope that some of them will later write brief explanations for us :)

    I believe that most of relatively easy (and at the same time working not so bad) ideas are related to local optimizations. I haven't read recent codes by top contestants yet :) But at first glance it seems so.

    While testing a problem, I tried a following very simple approach: generate some random approximation and run a hill climbing by doing flips of a single cell (picked randomly). Even with an unoptimized code and without any additional heuristics it scores below 15k points — so it would be probably enough to get #7 in a contest without any additional effort.

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4 years ago, # |
  Vote: I like it +24 Vote: I do not like it

Thanks to everyone fore participating :) It's nice to see a lot of high rated coders in standings. Also thanks for a lot of action at the top of the standings in last few hours (and even last few minutes), it was interesting to watch it.

I hope you managed to understand statement of Good points :)

Short editorials for standard tasks and codes by author and tester have been added now. They will be extended with some more details later; I hope that some sort of editorial for approximate task will be also ready a bit later.

Feel free to ask any questions and discuss problems.

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

    Where are the editorial? I couldn't find it.

    UPD: No need to answer; I've found it now.

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    4 years ago, # ^ |
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    Thank you for such a nice contest . I have a request please make editorials according to your own solution. It helps the understanding process. In editorial of DigIT you used 3-D dp of position remainder flag while in solution it is 4 -D dp. of which i have no clue what state represents

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      4 years ago, # ^ |
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      Thanks for pointing it out. That part comes from an old draft; now I have fixed it.

      Missing parameter is used for storing sum of digits.

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

        There is a typo states represents [position][remainder][sum] [flag] and not [position][sum]premainder][flag]

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4 years ago, # |
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Can anyone explain me , in the Setter's solution , how taking magic constant to be 5000 is giving a good speed up ? If A is 1 , B is 10^13 and K is 5000 so we have to check all numbers from 5000 to 10^13 in gap of 5000 and there are 2 * 10^9 such numbers . Won't this time out ?

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4 years ago, # |
  Vote: I like it +16 Vote: I do not like it

Thank you so much for a quality contest, guys. The participation was great, also the problems were pretty interesting, as well. The moment when I managed to understand the idea behind Good points was amazing. Tricked us all! :D

@I_love_Tanya_Romanova: I've forwarded your comments/feedback regarding to comments to the Dev team, by the way. I'm sure that it will be taken care of in future contests. :)