Unfair Codechef Ratings



So due to some small mistake a while ago when my rating was dropped by around 500 points for plagiarism in a really old contest, I didnt say anything. I gave the June Long Challenge and to my surprise, despite having 500 points and a ranking of 71, I got an increase of just 200 points, while some other people of my college, some having solved only 2 questions got a boost of 175 points. Is there any basis behind this? What’s the point of a lower rated person even solving the questions in long challenges then? Someone please look into this as I am not the only one pissed off by this.


Actually the fault here is that Codechef is treating people whose ratings have fallen because of Plagiarism equivalent to people who actually have that low rating ! It just that there is no seperate raings increasing system for them.
Don’t worry, just give all the rated contests happening , even if you don’t perform good your ratings will increase much. Now that you are wrong and have been involved in Plagiarism, you do deserve this ! (Though I have also been a part of Plagiarism but I did it because of having multiple accounts of mine on CodeChef.)

Inshort, nothing is unfair here, you were the one using unfair means !


Rating change depends on various factors. It depends on the current rating of all users, volatility of all users. Based on these two factors, expected rank is calculated. As you perform better and better as indicated by expected rank, your rating change will be higher and higher. However, the maximum rating change allowed for a user has its restrictions. If if you score 1st rank, your rating will not increase by more than the limit.
This limit depends on your current rating and the number of contests in which you have participated and is calculated as 100 + 75/(noOfContests+1) + 500*100/(|1500-Rating|+500). I have gone through your profile and your maximum rating change was 100 + 75/5 + 50000/591 = 199.60 = 200. Hence your rating change was 200. Since your previous rating was 1409 and upto 1800 are allowed in Div 2, therefore your expected rating for 0 change was too low. And you performed much better than that.
Check out this predictor.


Even My rating doesn’t shoot more than 130 or so. Okay we Did mistake but then we paid for it as a part of plagiarism Hammer. Now our rating should increase as per our performance how much good I perform my rating change is almost a fixed value. I mailed @vijju123 quite a few times but I got reply that @admin is working on this. I don’t know what they are upto but I feel that we have paid enough by rating drop. Now we should get rating increase as per our performance; the increase shouldn’t be restricted to some fixed value.


These people don’t even analyze the plagiarism issues seriously… They reduced some 600+ points for me for the contest FEB18, when some unknown idiot committed plagiarism & copied my code from ideone.com and submitted it 8 days later!

Guys if you can’t resolve those issues completely, don’t even do it period.


I will have to agree to the fact that making code private is mentioned on every contest page. It is kind of your fault if you never care to read the contest rules even. Although, People MUST be given a chance ti explain themselves.


I took place 44 in June Challenge 2018 Division 2 but only increased “by 186” from 1341 to 1527

@gur_chella ya took place 71 and increased dramatically “by 200” from 1409 to 1609

I ain’t think that unfair =))


I think that codechef has a fair rating system. Codechef rating is always calculated on the basis of your current performance and previous performance. If you are good coder and suppose somehow due to plagiarism your rating drops then if you continue to perform as you perform earlier your rating will increase much faster till your previous performance rating. After that you if do perform more better than your rating will increase much.
Means it also test that if in every contest you have 500 points and you again score 500 points then your rating will not increase much, because the level in which you are is according to your level. So, for increasing your rating always try to perform better than your previous performance.


I have notified the issue and was assured that some action would be taken.

But still, my rating increase is bottle-necked to 130.


Link to some example profiles please.


@vijju123 I think he is right.


I cannot post them publically right? That would be public shaming. I can message you in private though. May I knowhow I can do that?


I still need some reference profiles to see and compare :(. Else how will @admin know whats the factor causing an issue, or if its an issue in first place?


Can i message them to you on facebook?


or codeforces?


Even i was using multiple accounts bro. Dont jump to conclusions. My other account was open at the time of submission, so i just copied my soln and re-submitted it. It was the easiest question of the contest so yea.


Both are inaccessible right now for me xD. Can you drop me an email?


ok. email id? :stuck_out_tongue:


Mentioned on his profile. :stuck_out_tongue:


How about not publishing your code for problems of running contests?