Heyo Codefoworcers!


Proof_by_QED and I are very delighted to invite you to participate in Codeforces Round 971 (Div. 4), which will start on Sep/03/2024 17:35 (Moscow time). There will be $$$7$$$ problems, with one split into three subtasks, to be solved in $$$2$$$ hours and $$$30$$$ minutes. We encourage you to participate and hope you have fun, regardless of your division!
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), you may choose to participate rated or unrated.
We want to express overwhelming gratitude to the following orzosities for making the contest possible:
Vladosiya for his awesome coordination and mesanu for reviewing the problemset once again.
Our MVTs (Most Valuable Testuwuers), satyam343 and Dominater069, for their dedicated contributions.
The rest of our army of testuwuers: omeganot, nika-skybytska, awesomeguy856, 18o3, Lilypad, chromate00, Sacharlemagne, ntarsis30, Prady, Non-origination, TheYashB, ETL, Orange905, MC3297, mathtsai, macaquedev, jcai972, and cj8450.
MikeMirzayanov for all that jazz.
01100 00000 11000 10011 00111 01000 10010 01001 01110 10100 10001 01101 00100 11000 01011 00100 00000 00011 10100 10010 10010 10011 00000 10001 10110 00000 10001 00011
UPD: The round will be unrated, even though m1.codeforces.com, m2.codeforces.com, and m3.codeforces.com were functioning correctly. While there were issues on the main site (which lasted more than an hour), no participant was able to view the leaderboard, ask a question, or receive an answer.









As a testuwuer I can confirm this contest has W rizz and you will get ratioed.
bruh
omg! cry contest again! (cry fan)
you depressed or sth? stop crying =D
XD
As a tester,
As a testuwuer, I can read Morse at 10 words per minute.
c.c. is best as expected
English version:
THIS CONTEST IS A DIV4 INDEED
THIS CONTEST IS A DIV4 INDEED
As a participant
.. ....... .... — .--. . ....... .. ....... .-- — -. .----. — ....... --. . — ....... -. . --. .- — .. ...- . ....... -.. . .-.. — .- ....... ---... -.--.-
i wanna be a testuwuer one day uwu
same
As a testuwuer, I must say the problems are uWu
as a tester, Dominater orz
Noice! cry round!
bricked_ orz
Xbalanque orz
Sidenote: I'll be off contests for a few months to just focus on improving skill. Hopefully I'll reach CM the next time I do contest!
I will root for your comeback bricked_ orz
I will pray for your success in future contests heavenly_principles orz
when will u be a Red red0
As a tester, I like chipotle.
cry is the best! cry cry cry :)
Div-4 is my only hope for AK :) Good luck to all!
I hope to get AK too. Good luck to you.
what does AK stand for ?
maythisjourneyleadsusstardownard
what does this even mean
how did you decode it ?
map the strings to decimals and decimals to alphabets (0-25)
Decoded message for the binary pattern at the end.
May this journey lead us starward
I wish you all good luck for div 4.
Three subtasks is crazy !
As a tester, I confirm the problems are as good as cry
I hope to reach Expert after this round!
Can u give Div4 contest as a rated participant being a Specialist?
no
hey as you can see my rank i am newbie and as a newbie i am going to as a newbie question " will it be rated for me" will i get score?
Yes, It will be rated for all participants with rating less than 1400. i.e. it will be rated for all newbies and pupils.
this aged like milk, xD
One genuine question to cry, from where do you get such good emojis ?
Yay! Div 4 Round
What is this message at end?
MAYTHISJOURNEYLEADUSSTARWARD
"01100 00000 11000 10011 00111 01000 10010 01001 01110 10100 10001 01101 00100 11000 01011 00100 00000 00011 10100 10010 10010 10011 00000 10001 10110 00000 10001 00011".split(' ').map(bin => parseInt(bin, 2)).map(x => String.fromCharCode(x + 65)).join('');
am i the only one who did this?
maythisjourneyleadusstarward
One task in three subtasks? omg, I had never seen that before! I hope the contest would be amazing, gl&hf
dcode.fr my beloved
May as well join in on the brainrot fun!
As a uwuriter, I hope you do well and UwU the OwO out of this round :)
Good emoji.
The binary code at end : May this journey lead us starward.
Another cry contest? Do we remember this Div 2 C with bad score distribution? https://mirror.codeforces.com/contest/1998 Or this Div 3 D "counting is fun"? https://mirror.codeforces.com/contest/1996
For Div 4 guys out there, be careful. Assume it's speedforces, cry doesn't like creating solvable for your level problems.
The Div 3 problem just used some well known math, I think it was very doable. As a tester though, I'm curious how you'll react to this contest.
like to get luck!
I am so excited about this div 4 Contest But, how come the Div 3 Round from yesterday not make me newbie I am still unrated And I solved a problem in it too
just wait for the system testing to finish, it should be over soon
may this journey lead us starward
MAY THIS JOURNEY LEAD US STARWARD
Cry Always make me Cry :(
Good luck everyone uwu
where is sum ??
I ate him
Proof_by_QED damn man that Display Picture hits hard :)
About 5 years ago ratings used to start from 1500. In my first contest I solved one problem and my rating got reduced to 1430 something. "do not have a point of 1400 or higher in the rating", I have not been able to touch 1400 since then, am I not considered a trusted participant?
u are a trusted participant .. ur current rating needs to be <1400
h
The Binary Code
may this journey lead us star wardAs a non-rated contestant, this is my first unrated round.
Surprise! It's become an unrated round for rated contestants too
first time to unrate, wish to solve 6 problem
aiming for 0 solved
uwu
hope to become specialist in this contest
First unrated contest (^^)
Got busted in the last Div3 and now again rated for DIV4, expecting to reach cyan again.
As a participant, orz BonTapHoa , nguyenkhangninh99 , lalid , huanjua , chikien2009 , Soab , Jackduy
hope to become pupil in this contest, good luck everyone
where is your bro "Sum" as cry and sum :) ?
How to participate in the contest?
just participate :))
I think it will be a great round!
01100 00000 11000 10011 00111 01000 10010 01001 01110 10100 10001 01101 00100 11000 01011 00100 00000 00011 10100 10010 10010 10011 00000 10001 10110 00000 10001 00011
If we map 00000 with 'a' and 00001 with 'b' and so on
It translates to : may this journey lead us starward
Don't be upset bro. This contest just not for you.[problem:E= 111,122,133,000]
do not unrate plsssssss
Div 4 contest after a month and it became unrated
So wonderful round! I was top 2000, but it became unrated :(
Div.4 always suffer from poor performance? not the first time to occur that! so why to be unratted? An unsuccessful decision
i agree that cf is always slow.. but today's condition was incomparable to any of the past contests..it was the worst today.. so it was correct to make it unrated ..
POV:
Codeforces is temporarily unavailable
Such good round but got unrated! I was prepared to do my best and reach Specialist. But codeforces became queueforces and then website crashed.
it was supposed to be my combeck round ;( as i was about to solve F it become unrated even though if it didnt crash i would have done much better
Is this unrated?
it is clearly said that it is unrated
Div 4 could be one of the only chances for noobs like me to get ratings improved.However,unrated.:( ......Hope for the next turn.
Codeforces server is Mike's phone.
managed to solve 6 problems within 1.5 hrs for the first time!
in the end..
it doesn't even matter , linkin park
very sad that the contest got unrated. Very fun questions
I could have gone back to specialist again if the contest was rated. This is just sad.
please rate this round 😭
I didn't find anything unusual, div3/4 has been always slow and lagging due to large number of participant.
why unrated this?
For me, I was unable to access Codeforces for almost an hour, so I had to participate in the contest on m2.codeforces.com. I believe the downtime was long enough to warrant making the contest unrated. Of course, there were also queue delays in previous Div. 4 contests, but they were limited to the beginning of the contest and were usually resolved within 15 minutes.
Apart from that, I feel sorry to hear the bad news, especially since the problemsetters must have worked hard to prepare for the contest.
Making the round unrated just for the sake of "speedforces" just doesn't make sense to me tbh. What matters more is someone who solves more problems will place higher than someone who doesn't. Also the situation is the same for everybody, so it doesn't affect much to whoever has the ability to solve more problems.
i dont think so...i think many of the participants could not even see the questions after 2 to 3 mins of the contest ... and it is not due to internet issue but the server was down so it was fair to make it unrated imo .. if it was after 2 or 1 and half hours then mayb making it unrated would have been unfair.. but the problem was from the very beginning
who can tell me how to do E?
binary search the answer over the range (k,k+n-1)
You can also reduce the equation to a quadratic formula (ignoring the absolute values)
The minimum value must be near the vertex or the roots of the equation.
Binary search
in G1, isn't the idea just find the longest consecutive subarray in the interval $$$ [l, r] $$$ and then answer for that query will be $$$ k - x $$$ where $$$ x $$$ is the length of longest increasing consecutive subarray. I was solving that with segment tree and some dp precalculation. Even my stress test couldn't find anything wrong.
Submission link
Here is a counter example:
let $$$A = [1, 0, 3, 0]$$$. Clearly, the longest consecutive subarray here is 1, so your solution would produce $$$4 - 1 = 3$$$.
However, let $$$A_2 := 2$$$ and $$$A_4 := 4$$$, then we can create a consecutive subarray with only 2 moves.
consider this example:
[1, 2, 10, 11, 12, 6, 7]
the answer for this array is 3, because using 3 operations, I can change the array into the following:
[1, 2, 3, 4, 5, 6, 7]
Whereas based on your reasoning the answer is 4.
Anyone who solved E in O(1)?
yes
I didn't gacha Yunli so I can't solve G. So reasonable.
yunli will come home
Cf really need to ramp up their scalability
Edit: Problems were really good. I enjoyed solving G1 and G2 a lot (though solved G2 just 5 mins after contest ended )
Or Thanos should snap his fingers one (or even two) times to drastically decrease the number of participants :)
Regardless of this contest being unrated, it was an insightful contest with an interesting set of problems!
I enjoyed the problems very much!!! thank you problem setters.
Ok who is it that plays osu!mania?
Please don't host div4 anymore if it can't handle such a large amount of participants :(
(the problem set was nice though)
People down-voting clearly don't get it. Guess what, just after I received the notification saying the contest is being made unrated, the platform became completely accessible to me. Before that I couldn't even open a problem on the mirror sites. The amount of traffic the platform faces during a Div 4 Contest is pretty huge. Let's make it clear — several people in the organizing team are putting their efforts to bring a good Div 4 contest. If all of that goes to trash due to queue issues, it's better to host them only if the site can handle high traffic.
Cryforces
System testing is taking too much time :(
i think you could still make it rated considering the fact that even if the main site worked poorly,m1 m2 and m3 were fine so you could still get around it. SO PLEASE GIVE RATINGS thanks:P
when can I submit in practice , it is still showing system testing 100%
I feel there is no herm in putting 1 or 2 hard problems as the final tasks in every round. Which’s beneficial for both unrated as well as rated participants. Unrated participants would have something to think of rest of the contest and rated would have something to upsolve :)
Guessed difficulty
A — 800
B — 800
C — 800
D — 1000
E — 1100
F — 1400
G1 — 1800
G2 — 2100*
G3 — 2700**
*I did not seriously look at G3 at all.
**I did not solve G2, but I understand the solution based on the editorial, and kind of figured it out, nut I suck at segtrees.
You think 'E' is only 1100?
yes, maybe 1200.
It is simply just binary search, and triangle formula.
I would have gotten +70 delta if this contest was rated...
Nope, the announcement was made and I choose to stop solving since that point (I think there's many people choose the same). But tbh ur speed in this contest is good so it's kinda unlucky.
I didn't even see the announcement (
i use m2
unrated?
i think you could still make it rated considering the fact that even if the main site worked poorly,m1 m2 and m3 were fine so you could still get around it. SO PLEASE GIVE RATINGS thanks
Nah, the moment it is announced unrated, there is no turning back, because at that point some people would stop caring about competing and not participate at their full capacity anymore, or even quitting the contest
Agree. When it is announced unrated,I just give up keep writing code and just go to sleep lmao.
My conest was severely laggy the entire time, with even the m1 m2 m3 code forces sites not loading. However, I still was able to solve ABCDE, under some of the worst conditions. Please make this contest rated
I hope this contest would be rated too.
I learnt a lot during this contest even though I cried due to speed.
I will do my best on your next contest.
Thanks cry
I solved G1 with segment tree and sliding window
279788103
nice solution
May This Journey Lead Us Starward.
G2
Solution using Suffix sums by Precomputing lesser values to the right [ONLINE]: 280036192
Solution using Mergesort Tree[ONLINE]: 280017871
Solution using Square Root Decomposition[OFFLINE]: 280049782
Who made problem F
I thought -firefly- made it, guess I was wrong