cry's blog

Codeforces Round 971 (Div. 4)
By cry, 2 years ago, In English

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:

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.

Editorial

  • Vote: I like it
  • +306
  • Vote: I do not like it

Comments Comments (144)
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2 years ago, hide # |
 
Vote: I like it +39 Vote: I do not like it

As a testuwuer I can confirm this contest has W rizz and you will get ratioed.

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

As a tester,

- .... .. ... -.-. --- -. - . ... - .. ... .- -.. .. ...- ....- .. -. -.. . . -..
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2 years ago, hide # |
 
Vote: I like it -9 Vote: I do not like it

i wanna be a testuwuer one day uwu

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2 years ago, hide # |
 
Vote: I like it +18 Vote: I do not like it

As a testuwuer, I must say the problems are uWu

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2 years ago, hide # |
 
Vote: I like it +24 Vote: I do not like it

as a tester, Dominater orz

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2 years ago, hide # |
 
Vote: I like it +5 Vote: I do not like it

Noice! cry round!

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2 years ago, hide # |
← Rev. 2  
Vote: I like it +4 Vote: I do not like it

[deleted]

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2 years ago, hide # |
 
Vote: I like it +12 Vote: I do not like it

As a tester, I like chipotle.

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

cry is the best! cry cry cry :)

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2 years ago, hide # |
 
Vote: I like it +5 Vote: I do not like it

Div-4 is my only hope for AK :) Good luck to all!

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

maythisjourneyleadsusstardownard

what does this even mean

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2 years ago, hide # |
 
Vote: I like it +18 Vote: I do not like it

Decoded message for the binary pattern at the end.

Spoiler

I wish you all good luck for div 4.

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2 years ago, hide # |
 
Vote: I like it +4 Vote: I do not like it

Three subtasks is crazy !

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2 years ago, hide # |
 
Vote: I like it +5 Vote: I do not like it

As a tester, I confirm the problems are as good as cry

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

I hope to reach Expert after this round!

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

One genuine question to cry, from where do you get such good emojis ?

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2 years ago, hide # |
← Rev. 2  
Vote: I like it +1 Vote: I do not like it

Yay! Div 4 Round

What is this message at end?

Spoiler
Spoiler
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2 years ago, hide # |
 
Vote: I like it +16 Vote: I do not like it

am i the only one who did this?

int main(){
    string s;
    int g;
    while(1){
        cin>>s;
        g=0;
        for(char x:s){
            g=g*2;
            if(x=='1')g++;
        }
        cout<<char('a'+g);
    } 
}

maythisjourneyleadusstarward

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

One task in three subtasks? omg, I had never seen that before! I hope the contest would be amazing, gl&hf

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2 years ago, hide # |
 
Vote: I like it +5 Vote: I do not like it

dcode.fr my beloved

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

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 :)

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

Good emoji.

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

The binary code at end : May this journey lead us starward.

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2 years ago, hide # |
← Rev. 2  
Vote: I like it -16 Vote: I do not like it

Another cry contest? Do we remember this Div 2 C with bad score distribution? https://codeforces.me/contest/1998 Or this Div 3 D "counting is fun"? https://codeforces.me/contest/1996

For Div 4 guys out there, be careful. Assume it's speedforces, cry doesn't like creating solvable for your level problems.

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

    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.

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2 years ago, hide # |
 
Vote: I like it +5 Vote: I do not like it

like to get luck!

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

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

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

may this journey lead us starward

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

MAY THIS JOURNEY LEAD US STARWARD

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

Cry Always make me Cry :(

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

Good luck everyone uwu

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

where is sum ??

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

Proof_by_QED damn man that Display Picture hits hard :)

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

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?

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

h

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2 years ago, hide # |
← Rev. 2  
Vote: I like it +1 Vote: I do not like it

The Binary Code

Spoiler
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2 years ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

As a non-rated contestant, this is my first unrated round.

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

first time to unrate, wish to solve 6 problem

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

aiming for 0 solved

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

uwu

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

hope to become specialist in this contest

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

First unrated contest (⁠^⁠^⁠)

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

Got busted in the last Div3 and now again rated for DIV4, expecting to reach cyan again.

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2 years ago, hide # |
← Rev. 6  
Vote: I like it 0 Vote: I do not like it

As a participant, orz BonTapHoa , nguyenkhangninh99 , lalid , huanjua , chikien2009 , Soab , Jackduy

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

where is your bro "Sum" as cry and sum :) ?

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

How to participate in the contest?

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

I think it will be a great round!

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

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

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

Don't be upset bro. This contest just not for you.[problem:E= 111,122,133,000]

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2 years ago, hide # |
 
Vote: I like it -12 Vote: I do not like it

do not unrate plsssssss

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2 years ago, hide # |
← Rev. 2  
Vote: I like it -12 Vote: I do not like it

Div 4 contest after a month and it became unrated

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2 years ago, hide # |
 
Vote: I like it -12 Vote: I do not like it

give more time and do it rated pls

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

So wonderful round! I was top 2000, but it became unrated :(

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

Div.4 always suffer from poor performance? not the first time to occur that! so why to be unratted? An unsuccessful decision

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    2 years ago, hide # ^ |
    ← Rev. 2  
    Vote: I like it +10 Vote: I do not like it

    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 ..

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2 years ago, hide # |
 
Vote: I like it +22 Vote: I do not like it

POV:

It's just one hour of
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2 years ago, hide # |
 
Vote: I like it +15 Vote: I do not like it

Such good round but got unrated! I was prepared to do my best and reach Specialist. But codeforces became queueforces and then website crashed.

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

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

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2 years ago, hide # |
 
Vote: I like it -22 Vote: I do not like it

Is this unrated?

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2 years ago, hide # |
← Rev. 2  
Vote: I like it -9 Vote: I do not like it

Div 4 could be one of the only chances for noobs like me to get ratings improved.However,unrated.:( ......Hope for the next turn.

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

Codeforces server is Mike's phone.

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

managed to solve 6 problems within 1.5 hrs for the first time!

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2 years ago, hide # |
 
Vote: I like it +12 Vote: I do not like it

very sad that the contest got unrated. Very fun questions

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

I could have gone back to specialist again if the contest was rated. This is just sad.

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

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?

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

    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.

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2 years ago, hide # |
 
Vote: I like it -11 Vote: I do not like it

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.

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

    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

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

who can tell me how to do E?

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

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.

brute force for stress test

Submission link

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    2 years ago, hide # ^ |
     
    Vote: I like it +23 Vote: I do not like it

    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.

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

    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.

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

Anyone who solved E in O(1)?

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

    yes

    Spoiler
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2 years ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

I didn't gacha Yunli so I can't solve G. So reasonable.

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2 years ago, hide # |
← Rev. 2  
Vote: I like it +7 Vote: I do not like it

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 )

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

    Or Thanos should snap his fingers one (or even two) times to drastically decrease the number of participants :)

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

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.

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

Ok who is it that plays osu!mania?

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2 years ago, hide # |
← Rev. 2  
Vote: I like it -14 Vote: I do not like it

Please don't host div4 anymore if it can't handle such a large amount of participants :(

(the problem set was nice though)

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

    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.

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

Cryforces

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

System testing is taking too much time :(

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

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

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

when can I submit in practice , it is still showing system testing 100%

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

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 :)

My personal opinion
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2 years ago, hide # |
 
Vote: I like it +9 Vote: I do not like it

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.

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

I would have gotten +70 delta if this contest was rated...

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

    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.

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

    I didn't even see the announcement (

    i use m2

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2 years ago, hide # |
 
Vote: I like it +4 Vote: I do not like it

unrated?

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2 years ago, hide # |
 
Vote: I like it -12 Vote: I do not like it

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

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    2 years ago, hide # ^ |
     
    Vote: I like it +18 Vote: I do not like it

    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

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

      Agree. When it is announced unrated,I just give up keep writing code and just go to sleep lmao.

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

    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

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

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

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

I solved G1 with segment tree and sliding window

279788103

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

May This Journey Lead Us Starward.

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

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

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21 month(s) ago, hide # |
 
Vote: I like it 0 Vote: I do not like it

Who made problem F

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