### Ashishgup's blog

By Ashishgup, 8 months ago,

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.

• +108

 » 8 months ago, # |   0 .
 » 8 months ago, # |   +1 Ah! That's not my Handle
•  » » 8 months ago, # ^ |   0 Fixed
 » 8 months ago, # | ← Rev. 2 →   -36 I wish I solve three problems in this contest.
 » 8 months ago, # |   -27 I am desperate to destroy this contest ᕙ༼=ݓ益ݓ=༽ᕗ
•  » » 8 months ago, # ^ |   +7 And I destroyed the contest. Man of my word ᕦ(ò_óˇ)
 » 8 months ago, # |   +66 As a participant, I hope the contest will run smoothly cough servers cough.
•  » » 8 months ago, # ^ |   +41 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
•  » » » 8 months ago, # ^ |   +44 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.
•  » » » » 8 months ago, # ^ |   +14 Sorry. Servers are not in my control — I've obviously asked CodeChef to look into the issues, and hope they are fixed.
•  » » » » » 8 months ago, # ^ |   +2 was looking forward to it for a month now.
 » 8 months ago, # |   -69 Reminder: Contest starts in 12 minutes.
•  » » 8 months ago, # ^ |   +54 When will servers start? Please add a reminder when it does
 » 8 months ago, # |   +13 Bruh wtf...same server error like previous contest.
•  » » 8 months ago, # ^ |   0 codechef before unacademy vs codechef after unacademy :_)
 » 8 months ago, # |   0 Guys, can anybody submit on this contest?
•  » » 8 months ago, # ^ |   +1 cannot
•  » » 8 months ago, # ^ | ← Rev. 2 →   0 It has just started working now I guess.. one of my submissions got judged
•  » » » 8 months ago, # ^ | ← Rev. 2 →   0 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).
•  » » 8 months ago, # ^ | ← Rev. 2 →   0 I'm seeing 405 Not allowed.Edit : My first contest where I'm literally not allowed to submit.
 » 8 months ago, # | ← Rev. 3 →   0 Couldn't Submit, server is too busy . Update : Judge is fast now
 » 8 months ago, # |   +25 Time to go to bed! Good Night Everyone!
 » 8 months ago, # |   +21 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.
•  » » 8 months ago, # ^ | ← Rev. 2 →   0 Even my problem statements are not loading :(Such issues really degrade the competing experience
 » 8 months ago, # |   +11 Ah. shit here we go again.
 » 8 months ago, # |   +38 Me after seeing server busy after waiting for 1 month for cookoff-
 » 8 months ago, # |   +6 Will it be rated Now ?
•  » » 8 months ago, # ^ |   0 mostly no
•  » » 8 months ago, # ^ |   +3 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!
•  » » » 8 months ago, # ^ |   +11 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.
•  » » » » 8 months ago, # ^ |   0 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.
•  » » » » » 8 months ago, # ^ |   +2 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.
•  » » » » » » 8 months ago, # ^ | ← Rev. 2 →   0 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.
•  » » » » » » » 8 months ago, # ^ |   +19 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.
•  » » » » » » » » 8 months ago, # ^ |   -12 maybe codechef should stop doing business using competitive programming and focus on improving the website .
 » 8 months ago, # |   +3 I hate codechef for this specific incident
 » 8 months ago, # |   0 It seems that there is something wrong on the server's end. I can't view tasks. It was my maiden contest on Codechef. So unlucky of me :(
 » 8 months ago, # |   +6 So many 503 or submission failed...
 » 8 months ago, # |   0 Error 503 server can't process request ;)
 » 8 months ago, # | ← Rev. 2 →   +44 behen ke lodo ko unacademy ki promotion krne se fursat mile tab na.
•  » » 8 months ago, # ^ | ← Rev. 2 →   0 good night!!
•  » » 8 months ago, # ^ | ← Rev. 2 →   -40 .
•  » » » 8 months ago, # ^ |   -21 tu codechef ka admin wagerah hai kya ? hai to site theek krwa bakchodi baad me kr lio
•  » » » » 8 months ago, # ^ | ← Rev. 2 →   +3 .
•  » » » » 8 months ago, # ^ |   0 abbey lodu
•  » » » 8 months ago, # ^ | ← Rev. 5 →   -16 bc bhadve. kyu gaand chat rha ha..ab yeh servers ka problem kitne saalo se ha.theek hona chaiye na.This should be their main priority right now.
 » 8 months ago, # |   +27 Amazing 503 page! I saw it so many times today, so can draw that with closed eyes now!
 » 8 months ago, # |   0 is this still rated?
 » 8 months ago, # |   +1 We dont need your promotion of unacdemy.Use that money to make server better!!!!
 » 8 months ago, # |   0 I don't understand what CodeChef is upto ;-;
 » 8 months ago, # |   0 Again waste of time and work for problem setters.
 » 8 months ago, # |   0 At least make the source code for codechef opensource at least some good coders can contribute.
 » 8 months ago, # |   0 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.
 » 8 months ago, # |   +26 Am I the only one who feels sad about ByteDance?
•  » » 8 months ago, # ^ |   0 codechef was better platform before this unacademy thing..i guess they wasted all their money and effor on unacademy!!
•  » » 8 months ago, # ^ |   0 ByteDance going to dead soon .
•  » » 8 months ago, # ^ |   0 Maybe that's the reason it is still rated .
•  » » 8 months ago, # ^ |   +1
 » 8 months ago, # |   +17
 » 8 months ago, # |   +15 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.
•  » » 8 months ago, # ^ |   -9 XDXDXD
•  » » 8 months ago, # ^ |   -13 Aur abb jo time ka loss hua hai use cover up karne ke liye abb hamko ek bandi maangta hai.
 » 8 months ago, # |   -13 codechef have to take div1 , div2, div3 not on same day. every time codechef not working properly .
•  » » 8 months ago, # ^ |   +21 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.
 » 8 months ago, # |   -29 Bruh we want another rated contest within 2-3 days ..make this shitty cookoff unrated!!!
•  » » 8 months ago, # ^ |   +14 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.
•  » » » 8 months ago, # ^ | ← Rev. 2 →   +6 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.
•  » » » » 8 months ago, # ^ |   +3 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.
•  » » » » » 8 months ago, # ^ |   -22 point out even 1 line from my comment which is dumb .
•  » » » » » » 8 months ago, # ^ |   0 I was being sarcastic about CodeChef, not about your comment. No offense man, I completely agree! :D
•  » » » » » » » 8 months ago, # ^ |   0 So by "dumbest reason" to what you were referring to ?
•  » » » » » » » » 8 months ago, # ^ |   0 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.
•  » » » » 8 months ago, # ^ | ← Rev. 2 →   0 do they extended the contest by 30 min? where they mentioned?...sorry found it :_ (
•  » » » » » 8 months ago, # ^ |   0 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."
 » 8 months ago, # |   0 I felt sorry for those problem setters..they work hard to make such good questions..But all their effor goes into water .
 » 8 months ago, # |   +8 Still rated? Do you realize that many participants left the contest after trying to continuously submit for more than an hour.
•  » » 8 months ago, # ^ |   +4 I guess they are thinking they will just post a sorry message and everyone will come back and participate in contest!!
 » 8 months ago, # |   -23 A big NO to CodeChef from today. BYE (-_-)
 » 8 months ago, # | ← Rev. 2 →   0 Good night CodeChef
 » 8 months ago, # | ← Rev. 3 →   0 I got AC on 2 problems, but my score is still shown 1. I tied refreshing several times, but it won't help.Edit:It's fixed now.
 » 8 months ago, # |   +11 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.
 » 8 months ago, # |   -12 1.Unbalanced DIV22.People losing their rating because of server.3.Codechef stubborn to not make it unrated even after 30 mins trouble.RIP
 » 8 months ago, # | ← Rev. 4 →   +10 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
•  » » 8 months ago, # ^ |   +2 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
•  » » » 8 months ago, # ^ |   +44 "Under 2 sec" is not very reassuring if the TL is 1.5 sec :D. Anyway, time to research polynomial libraries.
•  » » » » 8 months ago, # ^ |   0 Oh, sorry, I mixed it up with a different problem then.
•  » » » » 8 months ago, # ^ |   +3 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.
•  » » » » » 8 months ago, # ^ |   +11 That's a tight limit but understandable if there was some slightly slower solution that you wanted to fail.
•  » » » » » » 8 months ago, # ^ |   -10 May be online FFT solutions were not intended to pass.
•  » » » » » » » 8 months ago, # ^ |   +3 Yes, that is true. TL was kept strict to prevent solutions based on online FFT to pass the test cases.
 » 8 months ago, # | ← Rev. 2 →   +2 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.
•  » » 8 months ago, # ^ |   0 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!
•  » » » 8 months ago, # ^ |   -16 My only motivation to participate was Ashishgup was a problem setter. STFU
•  » » » » 8 months ago, # ^ |   0 Hahahhahah who hurt you man?
 » 8 months ago, # |   0 I don't understand why can't they have pretests like codeforces?
•  » » 8 months ago, # ^ |   0 I think the the number of tests is already pretty low. Reducing them even more will probably cause many wrong submissions to pass.
•  » » 8 months ago, # ^ |   +16 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.
•  » » » 8 months ago, # ^ |   +19 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.
 » 8 months ago, # |   +38 Brief explanations of my solutions to Div. 2 (and Div. 3): https://www.youtube.com/watch?v=Q9gvoRXwqLM
•  » » 8 months ago, # ^ |   +19 Congratulations in advance on getting into Div 1 in Codechef :)
•  » » » 8 months ago, # ^ |   +44 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 :)
•  » » » » 8 months ago, # ^ |   +21 Hoping that they will not do this to you again :)
 » 8 months ago, # | ← Rev. 2 →   -84 The server is totally unavailable for atleast an hour and create a lot of problem, so as codechef is a international level platform and its ratings matter alot you should keep this contest unrated. Ashishgup FastestFinger ExplodingFreeze Um_nik Xellos amnesiac_dusk
 » 8 months ago, # |   +2 so no one is going to talk about level change of todays contest div2 than earlier contests...
 » 8 months ago, # |   0 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.
•  » » 8 months ago, # ^ |   -16 Thanks for the fast editorials
 » 8 months ago, # |   +34 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 ?
•  » » 8 months ago, # ^ |   0 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.
•  » » » 8 months ago, # ^ |   0 Why is this the worst case ? can you provide some intuition ?
 » 8 months ago, # |   +64 Congratulations to tourist for reaching 4000+ on CodeChef, leading the global second place by around 1000 rating points. Insane!