Ashishgup's blog

Invitation to CodeChef January Cook-Off 2021
By Ashishgup, 3 years ago, In English

We invite you to participate in CodeChef’s January Cook-Off, this Sunday, 24th January, from 9:30 PM to 12:00 AM IST.

There will be 3 divisions, each division containing 6 problems!

This CookOff, ByteDance is joining CodeChef as the official contest recruiter! The tech giants, who have their presence globally established through a range of content platforms, are looking to hire for multiple positions for their Singapore office, including — Algorithm Engineers, Backend Engineers, Data Engineers, Data Scientist, Machine Learning Engineers, Research Scientists, Frontend Engineers, Quality Assurance Engineer, Research Engineers, Software Engineer, and Site Reliability Engineers.

Joining us on the problem setting panel are:

Problem Submission: If you have original problem ideas, and you’re interested in them being used in CodeChef's contests, you can share them here.

Prizes: The top 10 Indian and top 10 Global participants will receive CodeChef laddus, with which the winners can claim cool CodeChef goodies. Know more here.

The video editorials of the problems will be available on our YouTube Channel as soon as the contest ends. Subscribe to get notifications about our new editorials.

Good luck and have fun!

Edit: Sorry for the server issues — it is mostly resolved now, reloading once or twice should work. The contest is extended by 30 minutes and will remain rated.

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

Comments Comments (84)
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3 years ago, # |
  Vote: I like it +1 Vote: I do not like it

Ah! That's not my Handle

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3 years ago, # |
  Vote: I like it -27 Vote: I do not like it

I am desperate to destroy this contest ᕙ༼=ݓ益ݓ=༽ᕗ

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    3 years ago, # ^ |
      Vote: I like it +7 Vote: I do not like it

    And I destroyed the contest. Man of my word ᕦ(ò_óˇ)

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3 years ago, # |
  Vote: I like it +66 Vote: I do not like it

As a participant, I hope the contest will run smoothly cough servers cough.

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    3 years ago, # ^ |
      Vote: I like it +41 Vote: I do not like it

    CodeChef has increased the number of checkers to handle higher submissions, and we have also reduced the testcases a little to keep the load low.

    Hopefully, things should be fine this time

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      3 years ago, # ^ |
        Vote: I like it +44 Vote: I do not like it

      In contest, that seems for nothing tbh.

      I can't even see the problem statements, let alone submit stuff.

      I don't understand how this happens in each and every contest, especially when you people claim to have increased server capacity.

      Off late, the problem quality on Codechef has gone up quite a lot, but these server issues make competing there a regrettable experience.

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        3 years ago, # ^ |
          Vote: I like it +14 Vote: I do not like it

        Sorry. Servers are not in my control — I've obviously asked CodeChef to look into the issues, and hope they are fixed.

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          3 years ago, # ^ |
            Vote: I like it +2 Vote: I do not like it

          was looking forward to it for a month now.

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3 years ago, # |
  Vote: I like it -69 Vote: I do not like it

Reminder: Contest starts in 12 minutes.

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    3 years ago, # ^ |
      Vote: I like it +54 Vote: I do not like it

    When will servers start? Please add a reminder when it does

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3 years ago, # |
  Vote: I like it +13 Vote: I do not like it

Bruh wtf...same server error like previous contest.

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

Guys, can anybody submit on this contest?

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    3 years ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    cannot

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

    It has just started working now I guess.. one of my submissions got judged

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

      Not working for me yet . It's actually working for a small time but showing error for most of the time (mostly when we are going to submit).

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

    I'm seeing 405 Not allowed.

    Edit : My first contest where I'm literally not allowed to submit.

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

Time to go to bed! Good Night Everyone!

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3 years ago, # |
  Vote: I like it +21 Vote: I do not like it

Rankings still show that I haven't solved a single problem, despite me being in top 80 with first two problems of D2. How come? Will servers really include me when they start working and impact my rank?

Sucks to say it, but CodeChef has been unusable since the beginning of December and it's getting worse every time.

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

    Even my problem statements are not loading :(

    Such issues really degrade the competing experience

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3 years ago, # |
  Vote: I like it +11 Vote: I do not like it

Ah. shit here we go again.

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

Me after seeing server busy after waiting for 1 month for cookoff-

images-2021-01-24-T220338-381

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3 years ago, # |
  Vote: I like it +6 Vote: I do not like it

Will it be rated Now ?

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    3 years ago, # ^ |
      Vote: I like it +3 Vote: I do not like it

    Probably not, I mean at least 50% participants already gave up on this nonsense. And yes, I believe it's safe to say that CodeChef team doesn't care about its participants. This, alongside massive cheating in Long challenges makes me question the whole purpose of this platform.

    We get 3 contests, one of which is unfair so it already cuts it down to 2 contests for me and most of us who are serious about our improvement.

    Now I wait for 20 days to see a single contest, which can end up with very shitty/trivial problems and on top of everything, the whole experience gets ruined due to the server issues.

    The server issues didn't exist 3 months ago, WTH happened to the platform? Why desperately try to solve problems that do not exist? Nobody thought it was a bad thing that solutions took 1-2 minutes to judge, the same thing happens with long queues on CF and it's not that big of a deal in 90% of the cases.

    The same goes for Div3 — nobody asked for it, yet we got 4th contest specifically designed for Div3 participants. This doesn't help the mediocre coders, only the complete newbies.

    Don't get me wrong, the overall quality of problems has increased very steeply and I admire the whole problemsetting team for that, but how can we enjoy it when we can't even read the problems normally let alone solve them with proper feedback?

    Please take this as a dose of cruel constructive criticism — these issues are really keeping people away from CC. Take a look at AtCoder and learn from what they are doing to improve their experience these days.

    I'm hoping to see an improved version of CC soon and wish the team doesn't let the community down!

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      3 years ago, # ^ |
        Vote: I like it +11 Vote: I do not like it

      The server issues didn't exist 3 months ago, WTH happened to the platform? Why desperately try to solve problems that do not exist? Nobody thought it was a bad thing that solutions took 1-2 minutes to judge, the same thing happens with long queues on CF and it's not that big of a deal in 90% of the cases.

      Maybe things were a bit more stable 3 months ago but Codechef has had various similar server problems at least as long as I have participated there (my first Codechef contest was about 5 years ago). Setters have always had to be ultra-careful when writing tests in order to not overload the system. It's great that there seemed to be no problem from your point of view but that doesn't mean there was no problem.

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

        Yeah, I see I'm slightly inexperienced with CC when you put it like that. I admit it was my mistake to judge like that. But as far as I can see we've gone from important issues to a completely unstable and unusable platform.

        Why wouldn't CodeChef introduce an unrated contest a day or two before the official one to test out the environment and cancel the contest if things don't work out? CodeChef gets an opportunity to see how things are doing 2-3 times a month, right? And the funny thing is — it never works out!

        Another extremely simple solution would be introducing pretests — and voila there we have it — a fully functional environment. CC provides this full feedback system which should make things better — but from your comment I can see nothing improved over the course of last 5 years!

        I'm guessing that it can't be that hard to create the whole described system, but perhaps I'm very wrong.

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          3 years ago, # ^ |
            Vote: I like it +2 Vote: I do not like it

          Another extremely simple solution would be introducing pretests — and voila there we have it — a fully functional environment.

          Have you seen the number of tests in the "successful submission" screen? Most of the time, it is less than 10, sometimes less than 5. Compare this to the number of tests in a Codeforces system test which is often more than a hundred. In fact the number of tests Codechef has is pretty close to the number of pretests in a non-Div2AB Codeforces problem: Codechef is already very frugal in terms of the number of tests problems get.

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

            I guess I'm out then. From what I can tell — there's no way to save CodeChef... Literally everything about it is messed up.

            I know it will sound very rude, but instead of trying to improve CodeChef CP community would benefit from CC contests being pushed over to CF.

            At this point CC is all about Unacademy shit, which they can pursue, people have already been saying goodbye to CC when it comes to contests.

            UPD: And by the way, thanks for letting me know all this info, I never really looked into the whole CC thing.

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              3 years ago, # ^ |
                Vote: I like it +19 Vote: I do not like it

              I think the only way to solve this problem to change their judge server from the current one (SPOJ) to something else completely. The current judge doesn't scale linearly with increasing servers due to database bottlenecks. Changing the judge server is a non trivial software engineering task and it seems that CodeChef has to bite this bullet sooner or later.

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3 years ago, # |
  Vote: I like it +3 Vote: I do not like it

I hate codechef for this specific incident

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3 years ago, # |
  Vote: I like it +6 Vote: I do not like it

So many 503 or submission failed...

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3 years ago, # |
← Rev. 2   Vote: I like it +44 Vote: I do not like it

behen ke lodo ko unacademy ki promotion krne se fursat mile tab na.

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3 years ago, # |
  Vote: I like it +27 Vote: I do not like it

Amazing 503 page! I saw it so many times today, so can draw that with closed eyes now!

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

is this still rated?

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3 years ago, # |
  Vote: I like it +1 Vote: I do not like it

We dont need your promotion of unacdemy.Use that money to make server better!!!!

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

Codechef should stop organizing short contests by now. Obviously they can't fix servers. Not even with all the money they get from the courses they sell. How hard is it, given that they hold only 2 short contests a month. Codeforces and AtCoder are sufficient for contests guys.

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3 years ago, # |
  Vote: I like it +26 Vote: I do not like it

Am I the only one who feels sad about ByteDance?

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3 years ago, # |
  Vote: I like it +17 Vote: I do not like it

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

Iss contest ko dene se acha mai hila ke so jaata jyada acha hota..... aadhe ghante se mouse hilla rha hun page hi nhi khul rha hai.

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3 years ago, # |
  Vote: I like it -13 Vote: I do not like it

codechef have to take div1 , div2, div3 not on same day. every time codechef not working properly .

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    3 years ago, # ^ |
      Vote: I like it +21 Vote: I do not like it

    No offense, but having Div1, Div2 and Div3 on seperate days makes even less sense, currently each division has 6 problems, but there are only 10 problems after common problems between divisions.

    If each division was on a separate day, there would need to be twice the number of problems which would be unfeasible, especially for the Medium or higher problems needed for the top problems of Div2.

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3 years ago, # |
  Vote: I like it -29 Vote: I do not like it

Bruh we want another rated contest within 2-3 days ..make this shitty cookoff unrated!!!

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    3 years ago, # ^ |
      Vote: I like it +14 Vote: I do not like it

    I don't think it works like that. Problemsetters take their time to come up with quality problems, and then you have the translators, editorialists, etc. People don't do this full time, it's mostly a hobby, so expecting the same team to come up with quality contest in a 2-3 day time-span is so ridiculous. But yeah, in the perfect universe, I'd like to see that as well.

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      3 years ago, # ^ |
      ← Rev. 2   Vote: I like it +6 Vote: I do not like it

      Why extended by 30 mins ? I have some other work after the contest usual ending time and they should make it unrated because it didn't worked for around 30 mins . It has also created lot of unfair rank gaps . Ashishgup please make it unrated else it would be unfair.

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        3 years ago, # ^ |
          Vote: I like it +3 Vote: I do not like it

        Haha — let me tell you something — it's unrated for me already — apparently based on rankings I didn't solve any problem.

        Come on — the whole thing is a joke. Just stop the contest now, there's literally no point in hosting, CC is just getting people to hate them for the dumbest reason possible.

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          3 years ago, # ^ |
            Vote: I like it -22 Vote: I do not like it

          point out even 1 line from my comment which is dumb .

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

            I was being sarcastic about CodeChef, not about your comment. No offense man, I completely agree! :D

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

              So by "dumbest reason" to what you were referring to ?

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

                I was referring to keeping the contest rated, instead of simply making it unrated after 30 minutes of issues. I hope it's clear now.

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

        do they extended the contest by 30 min? where they mentioned?...sorry found it :_ (

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

          Read the announcements — "Sorry for the server issues — it is mostly resolved now, reloading once or twice should work. The contest is extended by 30 minutes and will remain rated."

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

Still rated? Do you realize that many participants left the contest after trying to continuously submit for more than an hour.

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

    I guess they are thinking they will just post a sorry message and everyone will come back and participate in contest!!

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3 years ago, # |
  Vote: I like it +11 Vote: I do not like it

Finally the ranklist updated, so I guess we're all on the same page now. If it stays rated, I have nothing against it now, maybe the difference in ranking will exist, but I believe it will be only slight.

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3 years ago, # |
← Rev. 4   Vote: I like it +10 Vote: I do not like it

Can you solve PART without finding the inverse series of a polynomial? If not, why are the limits so tight (my solution was to find $$$D(x) = \frac{1}{1 - P(x)}$$$ where $$$P(x)$$$ is a polynomial of degree $$$n$$$)?. The cp-algorithms library was too slow here T_T

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    3 years ago, # ^ |
      Vote: I like it +2 Vote: I do not like it

    That's the intended solution, my implementation with copy-pasted from some japanese guys polynomial stuff works well within TL/2, setter's hand-written solution is a bit slower, but also under 2 sec

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      3 years ago, # ^ |
        Vote: I like it +44 Vote: I do not like it

      "Under 2 sec" is not very reassuring if the TL is 1.5 sec :D. Anyway, time to research polynomial libraries.

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

        Oh, sorry, I mixed it up with a different problem then.

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        3 years ago, # ^ |
          Vote: I like it +3 Vote: I do not like it

        Finally reached from bed to the laptop, my sol works in 0.5, setter's and tester's are around TL/2. Once again sorry for initial confusion.

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          3 years ago, # ^ |
            Vote: I like it +11 Vote: I do not like it

          That's a tight limit but understandable if there was some slightly slower solution that you wanted to fail.

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            3 years ago, # ^ |
              Vote: I like it -10 Vote: I do not like it

            May be online FFT solutions were not intended to pass.

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              3 years ago, # ^ |
                Vote: I like it +3 Vote: I do not like it

              Yes, that is true. TL was kept strict to prevent solutions based on online FFT to pass the test cases.

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

In my Opinion, It should be unrated, and it's wasting contestants time and problemsetters efforts.

for more than 30 minutes, the site was down, 503 error everywhere, can't submit and I can't even read the statements, and of course after 30 minutes of refreshing and waiting for codechef to work again and it didn't happen so I went to watch Liverpool vs Man United match and I bet others did that as well. How it's going to be rated !!!!!!!

codechef should make testing contests, it's not the first time that something like that happen.

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

    As a Div 3 participant, it was not so bad.

    Yes, I was frustrated at times but that was more than made up by the quality of questions. So it's okay. Shit happens. Things will improve.

    My only motivation to participate was Ashishgup was a problem setter. And he delivered. So thanks for that!

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

I don't understand why can't they have pretests like codeforces?

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

    I think the the number of tests is already pretty low. Reducing them even more will probably cause many wrong submissions to pass.

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

    Because underlying judge is not written to allow such things. Also this contest didn't have big judging queue, it was just server issues, pretests wouldn't help with that.

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      3 years ago, # ^ |
        Vote: I like it +19 Vote: I do not like it

      Actually maybe it is possible to have pretest. Before the contest, in the test sequence field you can fill only the tests that will work as pretests. After the contest update the sequence, and rejudge all submissions that got AC. Similar to how the challenge problem displays the score only on public test files during contest. It requires some manual work, personally I prefer to have full feedback during contest.

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

Brief explanations of my solutions to Div. 2 (and Div. 3): https://www.youtube.com/watch?v=Q9gvoRXwqLM

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    3 years ago, # ^ |
      Vote: I like it +19 Vote: I do not like it

    Congratulations in advance on getting into Div 1 in Codechef :)

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      3 years ago, # ^ |
        Vote: I like it +44 Vote: I do not like it

      I actually made it into Div. 1 on my last contest, but they changed the division cutoffs in between so I had to do it again :)

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        3 years ago, # ^ |
          Vote: I like it +21 Vote: I do not like it

        Hoping that they will not do this to you again :)

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

so no one is going to talk about level change of todays contest div2 than earlier contests...

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

Video editorials for 6 problems have been uploaded here. The remaining videos will be uploaded in a couple of days. And the editorials for 8 problems can be found here. The remaining 2 will be published in a day.

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

EQLGIFTS : Can someone prove why there always exists two different subsets with equal sum for n >= 28 ? For n >= 32 it can be easily proved by using Pigeon Hole principle. I am wondering how to improve this bound to 28 ?

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

    Maybe this way... worst case is with 1,2,4,8,16,.. 2^26... after this 2^27 is out of range and any other no. u add can be formed with above 27 no.s (from 2^0 to 2^26), so with 28 no.s u are gurranteed of a collision.

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3 years ago, # |
  Vote: I like it +64 Vote: I do not like it

Congratulations to tourist for reaching 4000+ on CodeChef, leading the global second place by around 1000 rating points. Insane!

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