Hello Codeforces!
SlavicG, flamestorm, MikeMirzayanov, Errichto, and I want to invite you to the long-awaited second Div. 4 round!
It starts on Apr/21/2022 17:35 (Moscow time).
The format of the event will be identical to Div. 3 rounds:
- 5-8 tasks;
- ICPC rules with a penalty of 10 minutes for an incorrect submission;
- 12-hour phase of open hacks after the end of the round (hacks do not give additional points)
- after the end of the open hacking phase, all solutions will be tested on the updated set of tests, and the ratings recalculated
- by default, only "trusted" participants are shown in the results table (but the rating will be recalculated for all with initial ratings less than 1400 or you are an unrated participant/newcomer).
We urge participants whose rating is 1400+ not to register new accounts for the purpose of narcissism but to take part unofficially. Please do not spoil the contest for the official participants.
Only trusted participants of the fourth division will be included in the official standings table. This is a forced measure for combating unsporting behavior. To qualify as a trusted participant of the fourth division, you must:
- take part in at least five rated rounds (and solve at least one problem in each of them),
- do not have a point of 1400 or higher in the rating.
Regardless of whether you are a trusted participant of the fourth division or not, if your rating is less than 1400 (or you are a newcomer/unrated), then the round will be rated for you.
Many thanks to the testers: senjougaharin, magnus.hegdahl, Vladosiya, MeGustaElArroz23, Sho, bakekaga, geranazavr555, doreshnikov, jampm, Neophiliatic, qwexd and VIP-tester _Vanilla_.
We suggest reading all of the problems and hope you will find them interesting!
Good Luck!
Update: Editorial
As a tester, https://discord.gg/mPACFtYvwF
Thanks to MikeMirzayanov for polygon platform.
Can we please get back to programming?
I truly don't mean for this to come off as insincere, insensitive, or trying to diminish the importance of these events to people's personal lives.
But that being said...
Codeforces isn't the place for such debates. I'm not saying these discussions don't need to happen. They do. But them happening on this surface is essentially well-intentioned spam.
This stuff belongs on social media, or places like Reddit and Discord.
Alright, I've spoken my peace, bring on the flood of downvotes...
I agree with you, but I downvoted you.
As a participant (hopefully), thank you for the round!
I was not expect this combination of authors. Will definitely be doing the contest.
Hope I turn Pupil this round
I hope too 555...
you did it!
哈哈谢谢啦
你也加油呀
You just reached rating 1200 :)
that's right.I still have a long way to go
I hope too... qwq
Don't think that you will turn pupil. Just hope that you'll learn something and get better. Former may make you depressed but latter will always make you happy
absolutley right!!
good luck
As a VIP-tester, I tested
Oh, that must be nice...
It's a Very Important Person — Tester. You can thank me later.
<3
as a potential participant, 接受我 公众 我需要现金
i can‘t understand
As a Chinese and not understanding.
maybe 接受 means accepted.
jampm the best tester Upd: the second best tester
Sorry but I do not see his VIP status, opinion rejected.
UPD: They realised I am the best tester.
u don't know anything
i cannot believe how CF got jampm for tester, he is known as a God. Very humble participating as tester.
From now, can we expect div-4 frequently ?
+1
Déjà vu...
I can't wait to see problem ratings lol
problem D will be very interesting i swear
As a participant, I hope to be unofficial to div4s after this contest.
same :c
done! I become a specialist.
What about score distribution ?
Div 3/4 and Educational rounds doesn't have score distribution.
Its just number of problems solved + penalty
"We urge participants whose rating is 1400+ not to register new accounts for the purpose of narcissism but to take part unofficially. Please do not spoil the contest for the official participants."
I respect that a lot.
...
finally my… nvm
As a participant, since when do div 4 contests exist lol.
As a self-proclaimed old guy, since about two years ago.
looking forward to 1900 rated F,G. (Totally not an analogy to 2000-2200 rated F,G problems in Div. 3 rounds, but they are sure very interesting for Div. 3 users when none of them can solve the problems xd)
My first Div.4 round. This is going to be interesting Thanks for the round!
looks like I got back to pupil from specialist just to participate in this contest officially xD
After a long time finally there is a (Div.4). (REALLY EXCITED) ٩ (◕‿◕｡) ۶
Specialists be like : Yo maann! Outta competition.(⌐■_■)
Just realized out of 10 Level of Colors
cyan (specialist) is the only unique official color in Div 3 Contests
Errichto it is a pleasure to see u after a long time .
What a great time to be rated 1399
This contest is just a joke, low rating participants should go to leetcode first.
i could say the same for u lmao
Anyone have link for the codeforces extension for the graph and all of this.
HAHA, I looked forward to my first unrated round, and it was supposed to be after a long time. But the Div.4 round comes. Thanks!!!
This will be my first unrated round. Good luck everyone!
https://mirror.codeforces.com/predownloaded/12/fd/12fd7093934406812ce5d61c9a4393249234b248.jpg
Good luck to all my fellow newbies and pupil. It's their time to shine. All the best :)
Can anyone give me the previous(1st) Div-4 round link, plz?
https://mirror.codeforces.com/blog/entry/77130
Hooray, round for my level)
my first unrated round
me too
I hope that I'll learn something and get better in a unrated round so that I can earn rates in a rated round.
Thanks to MikeMirzayanov for polygon platform and CodeForces team!
Feels weird to say MY FIRST UNRATED ROUND!!
LOL xD.
First unrated round for me)
Is it rated?
Not rated for you however.
FastFingersForces
Previous div4 was probably harder than this
fanserviceforces
D is the hardest
The easiest contest ever proposed in the history of universe.
I went rainboy mode in this contest.
There are many accounts that was made just yesterday and they are in the top 100 lol
Great round for 4th division!
Fastest finger first
Here's my 22 minute speedrun with solutions to all problems at the end. Enjoy :)
Wonderful Contest!!
Thanks for the contest!Interesting and good problems!
.
You are modifying the input strings themselves, pretty sure you can't do that.
Can organizers look into this issue. My rank states that I solved all question in 205 penalty and shows rank 265.
My rank
But the penalty of ranks around 260 is way too high and my name is also not in the ranklist.
Ranklist
Am I the only one or someone else also facing this issue ?
The rank list contains only trusted participants. Whereas your contest rank is shown in friends section
But I am a trusted participant.
Then in that case you should tag the organizers.
mesanu, SlavicG, MikeMirzayanov Can you please look into this?
You are not a trusted participant
you should not have a point in your graph when your rating was >= 1400
Yes. do not have a point of 1400 or higher in the rating
Oh, Thanks for the clarification.
could not solve E,brute force obviously failed,though of merge sort but could not think how it will be impelemnted here.can someone help?
Keep count of strings that end in character c and that start with character c. Also keep count of all strings in total.
For any string s, remove it from the counts, add number of strings that end in s[1], number of strings that start with s[0], and subtract count of [s] to avoid overcounting in case s occurs more than once in the list.
154325997
LightspeedForces / HyperspeedForces
Since got used to some tight time limits in harder problems I was trying to get a solution of each problem by using (if you will) smart strategy, but now I checked some other solutions and people just pass all test cases with 3, 4 for loops, bunch of while loops etc. :)
How to do E? I did a somewhat $$$O(n^2)$$$ solution and it gave me TLE.
combinatorics ig
suppose you are at index i, and you have stored all previous string instances in map
if you have string ab at this index than
you can change first char and check no. of occurrence of all such strings
e.g. for ab -> bb, cb, — kb are such possible strings
Similarly you can change second char and check no. of occurrence of all such string
e.g. for ab -> aa, ac, ad ---- ak (after changing second char)
just add all instances to your solution
You can check my solution : https://mirror.codeforces.com/contest/1669/submission/154337766
Thank you all!
where can i get today contest answers? i am curies to refer them
You can check out this video by SecondThread.
the editorials are out. You can read them now...
Some will say this was a speedforces and this had not many interesting problems. But believe me when I was a beginner I always dreamed of a round where I could have solved more than 3 problems and that could have given me the gear that I was needing to accelerate my learning skills. For me this type of rounds should take place atleast once in every 1.5 months.
woohoo first time to experience the feeling of solving all the problems during a contest. it's way better than I thought
self-deception forces
I answered question number b, But the site told me that the answer is wrong, please tell me where the mistake is my code is here https://mirror.codeforces.com/contest/1669/submission/154405569
https://www.geeksforgeeks.org/difference-between-and-equals-method-in-java/
Did you guys faced problem?codeforces was too slow for me.I was waiting for almost 5-10 minutes after clicking on one link.
me too
Why this solution 154288735 WA?
You're mixing output streams (cout and puts) and they don't keep their order because the sync with stdio thing is set to false. I just commented that line and accepted.
Thank you
was this first div 4 round
Nope.
This is the first one.
https://mirror.codeforces.com/contest/1352
Good contest see you all in other two years
When the rating is going to be reflected?
a few hours after hacking+systests.
is it only me or the round actually previously stated rated for<=1400 Now says "do not have a point of 1400 or higher in the rating."
That is the condition of being a trusted a participant
It is rated for you and everyone who has rating < 1400
Oh..got it
To not keep you waiting, the ratings are updated preliminarily. In a few days, I will remove cheaters and update the ratings again!
Hi... I am receiving messages from the system that my solutions for this contest coincide with shrey_gta. I am sorry for my actions, but I have not done anything wrong or cheated. shrey_gta is my alternative id and I first gave my contest with that id only. Then after that, I submitted all the solutions in one go from my main handle. Also, this contest was not rated for this handle. I kindly request MikeMirzayanov to look into this matter and not block any my handle. I am again sorry for my actions and will not repeat those actions in the future. Thank You
BKL mike you can't be negative
why this sub 154484811 for F gives TLE ?
You should pass the vector argument to function bs by reference, not by value. The way you doing it it is copied each time.
Thanks for the authors, it was fun! Hope there will be more Div 4 contests in the future.
I hope repeating this contest as the same as div 2 and div 3 Thanks for this amazing one!
F in the chat for the codeforces rating predictor, it overpredicted everyone’s rating by almost 30
This round should be unrated. I faced a lot of problems. Codeforces was too slow.Many times were wasted for this. After that I became bored and left the contest. It is not fair to rate this round. I even asked the authority whether it was my problem or their. They told they were trying to fix it.
Hello MikeMirzayanov My F problem is caught in plagiarism but have solid evidence that I don't stole it and I have solid proof. What should I do?
Hello,
[user:SlavicG,MikeMirzayanov,][user:mesanu][user:Errichto] I got plagiarism on My F problem in this contest is coincedence and I have a solid proof about it. Now what should I do?_
.
I just the got the mail regarding palagrism.Your solution 154314647 for the problem 1669C significantly coincides with solutions Ashishpurbey/154314647, Ashishpurbey/154322351. Such a coincidence is a clear rules violation. Note that unintentional leakage is also a violation. For example, do not use ideone.com with the default settings (public access to your code). If you have conclusive evidence that a coincidence has occurred due to the use of a common source published before the competition, write a comment to post about the round with all the details. More information can be found at http://mirror.codeforces.com/blog/entry/8790. Such violation of the rules may be the reason for blocking your account or other penalties. In case of repeated violations, your account may be block.
I hadn't copied any code from any where, I just submmit the same code twice and because of the glitch on codeforce it summited .They are comparing both code from the same ID and giving palagrism. So I requested you to visit this glitch one more time and retuned my rating back.
Your text to link here...
I'll fix all such issues after the global round or tomorrow.
I got these messages but I don't know how these codes are similar. I have never done such things and also never got such messages before and what will I do after cheating in DIV-4 as it was already unrated for me;). MikeMirzayanov Please look into it.
Attention!
Your solution 154361635 for problem 1669G significantly coincides with solutions coder_vk/154361635, Daqlet/154366245. Such a coincidence is a clear rules violation. Note that unintentional leakage is also a violation. For example, do not use ideone.com with the default settings (public access to your code). If you have conclusive evidence that a coincidence has occurred due to the use of a common source published before the competition, write a comment to post about the round with all the details. More information can be found at http://mirror.codeforces.com/blog/entry/8790. Such violation of the rules may be the reason for blocking your account or other penalties. In case of repeated violations, your account may be blocked.
Solutions- https://mirror.codeforces.com/contest/1669/submission/154361635 https://mirror.codeforces.com/contest/1669/submission/154366245
Attention!
Your solution 154365782 for the problem 1669H significantly coincides with solutions coder_vk/154365782, Daqlet/154372523, bhadrayu_18/154412978. Such a coincidence is a clear rules violation. Note that unintentional leakage is also a violation. For example, do not use ideone.com with the default settings (public access to your code). If you have conclusive evidence that a coincidence has occurred due to the use of a common source published before the competition, write a comment to post about the round with all the details. More information can be found at http://mirror.codeforces.com/blog/entry/8790. Such violation of the rules may be the reason for blocking your account or other penalties. In case of repeated violations, your account may be blocked.
Solutions- https://mirror.codeforces.com/contest/1669/submission/154365782 https://mirror.codeforces.com/contest/1669/submission/154372523 https://mirror.codeforces.com/contest/1669/submission/154412978
MikeMirzayanov any good news about this issue ?
up up ⬆️
Hello,
I got a mail about plagiarism and I'm sure that this one is happened because of some coincidence or straight logic question.
MikeMirzayanov,SlavicG,flamestorm. I wrote code on my own and as you can see that in this submission 154392853 I got TLE on my submission and then I changed my code a little bit like this 154393751 and this one was accepted because of binary search has less time complexity.
PLEASE check out this. I hadn't copied any code from any where. So I requested you to visit this submissions and see what I changed in my code and got AC in my submission one more time and retuned my rating back.
check here
don't worry , I had the same issue https://mirror.codeforces.com/blog/entry/102171
also check this comment :
https://mirror.codeforces.com/blog/entry/102053?#comment-906182
MikeMirzayanov please read it out.
MikeMirzayanov any update about this issue...????