Stepavly's blog

By Stepavly, 13 months ago, translation, In English

Unfortunately, due to Internet provider network issues, we have to postpone the round. The current plan, that the round is postponed by 24 hours, will start on May/05/2021 17:35 (Moscow time).

Hello, Codeforces!

<almost-copy-pasted-part>

Hello! Codeforces Round #719 (Div. 3) will start at May/05/2021 17:35 (Moscow time). You will be offered 7 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating 1600 or higher, can register for the round unofficially. The round will be hosted by rules of educational rounds (extended ICPC). Thus, during the round, solutions will be judged on preliminary tests, and after the round, it will be a 12-hour phase of open hacks. I tried to make strong tests — just like you will be upset if many solutions fail after the contest is over.

You will be given 7 problems and 2 hours to solve them.

Note that the penalty for the wrong submission in this round (and the following Div. 3 rounds) is 10 minutes.

Remember that only the trusted participants of the third division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as trusted participants of the third division, you must:

  • take part in at least two rated rounds (and solve at least one problem in each of them),
  • do not have a point of 1900 or higher in the rating.

Regardless of whether you are a trusted participant of the third division or not, if your rating is less than 1600, then the round will be rated for you.

The problems for this round were invented by MikeMirzayanov, Supermagzzz, Stepavly and Aris.

Thanks to Gassa, BledDest, Programmer, bugdone, ruban, RedAnt, songsinger and Gornak40 for help with testing the round.

Thanks to MikeMirzayanov for platforms and coordination of our work. Good luck!

</almost-copy-pasted-part>

Editorial is ready!

 
 
 
 
  • Vote: I like it
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13 months ago, # |
  Vote: I like it -71 Vote: I do not like it

Most awaited round of the month.

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13 months ago, # |
  Vote: I like it +26 Vote: I do not like it

My first rated contest pretty excited :)

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    13 months ago, # ^ |
      Vote: I like it +21 Vote: I do not like it

    First rated contest with a new Alt? :P

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      13 months ago, # ^ |
        Vote: I like it -15 Vote: I do not like it

      as I am a beginner, my friend suggested giving div 3 as they have some easy problems, so waited for a div 3 :)

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    13 months ago, # ^ |
    Rev. 2   Vote: I like it +42 Vote: I do not like it

    My first unrated div 3 :)

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    13 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    All the best!

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    13 months ago, # ^ |
    Rev. 3   Vote: I like it +2 Vote: I do not like it

    Everyone !! Did any Rating changes occurred I am unable to see any rating changes for me, So here I am asking ! -_-

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      13 months ago, # ^ |
      Rev. 3   Vote: I like it 0 Vote: I do not like it

      Same here, and even it is showing in unrated contest in my profile

      however I am on official standings

      Can't wait for rating changes.

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        13 months ago, # ^ |
          Vote: I like it 0 Vote: I do not like it

        Until rating is actually credited/debited in your profile, Every contest is shown in unrated.

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      13 months ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      They just did another system testing. Wait for 2 hours now and hope no more system testings.

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13 months ago, # |
  Vote: I like it +55 Vote: I do not like it

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13 months ago, # |
  Vote: I like it -15 Vote: I do not like it

Sorry but I don't really understand the trusted rules :( Does that mean I can't use clones?

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13 months ago, # |
  Vote: I like it -46 Vote: I do not like it

Div. 4 when?

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    13 months ago, # ^ |
    Rev. 3   Vote: I like it -41 Vote: I do not like it

    What is div 4 ?

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      13 months ago, # ^ |
      Rev. 2   Vote: I like it +15 Vote: I do not like it

      Does a contest always mean solving hard problems :)? Even a div. 4 contest with easy/tricky problems can be fun at times.
      What I think is, coding is not always about solving hard problems, let there be fun.

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        13 months ago, # ^ |
          Vote: I like it +2 Vote: I do not like it

        I can't disagree, but what's the point of solving easy problems if they don't bring you any benefit, just a waste of time? is not it ?

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          13 months ago, # ^ |
            Vote: I like it +2 Vote: I do not like it

          I think solving easier problems(which we can solve faster), can be a really good warm-up.
          Sometime when I feel dull, or like I am unable to perform well, I go for solving some easier problems. That really helps in gaining pace.

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            13 months ago, # ^ |
              Vote: I like it -7 Vote: I do not like it

            Where do such good arguments come from?)

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            13 months ago, # ^ |
              Vote: I like it +3 Vote: I do not like it

            yes, agreed but most of the people asking for div 4 are generally doing it just in hope of positive rating.

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      13 months ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      nice argument

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      13 months ago, # ^ |
        Vote: I like it +11 Vote: I do not like it

      Funny calling him noob when he has a rating higher than you.

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13 months ago, # |
Rev. 2   Vote: I like it +12 Vote: I do not like it

Really excited for my second contest , hoping i would cross 1000 this time. Any tips are welcomed. TIA

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    13 months ago, # ^ |
      Vote: I like it +11 Vote: I do not like it

    Enjoy beauty of contest, never think about rating and never go for cheating.

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      13 months ago, # ^ |
        Vote: I like it +1 Vote: I do not like it

      thanks buddy, really a well defined ans.

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    13 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    You did really well in your first round, you will soon be in top trust me. I still struggle to get above 6000 rank. Hoping to get better with future contests.

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    13 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    WTF! You solved 4 in Global round and still got a positive delta of only 600?

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13 months ago, # |
  Vote: I like it -18 Vote: I do not like it

how to become red coder in 1 month???? any tips and tricks???

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    13 months ago, # ^ |
      Vote: I like it +40 Vote: I do not like it

    Yes, just win every contest you step in and you'll be red within a month

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    13 months ago, # ^ |
      Vote: I like it +39 Vote: I do not like it

    Wait for January 2022, you will don't have to wait a month, 1 sec would be good enough. xD

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    13 months ago, # ^ |
      Vote: I like it +6 Vote: I do not like it

    I became a LGM in January and posted on social media just to baffle my friends.

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    13 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    start in December and when new year comes, they will give you an option to change your color for few days. That's my secret of becoming a red coder.

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    13 months ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    yes, there are two ways either you paint your laptop screen with red colour , or solve 3000 plus questions in a month ,lol

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    13 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Few years ago,when the initial Rating was 1500,LxL became gold only after three div.2s.

    Becoming red in 1 month? Just go to bed and have a good dream. There is everything in dreams.

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

My chance to become a pupil

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    13 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    solve 3 problems in tomorrows div 3 contest...u will surely reach pupil

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13 months ago, # |
  Vote: I like it +13 Vote: I do not like it

Hmmm, why aren't we seeing vovuh as a problem setter in recent div.3 contests?

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    13 months ago, # ^ |
      Vote: I like it -6 Vote: I do not like it

    I hope he's not COVID positive in these uncertain times.

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    13 months ago, # ^ |
      Vote: I like it +2 Vote: I do not like it

    Stepavly contests are like the old DIV 3.5, Vovuh DIV 3's were, indeed, a bit tricky especially the latter problems.

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Hope to see a cool problemset. Best of luck, All.

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    13 months ago, # ^ |
      Vote: I like it +16 Vote: I do not like it

    As a tester I can assure you the problem set is cool :)

    Also be sure to read all the problems. Setters often write this, but in Div2 I think most of the time the last problems are really hard. But for Div3 I think it's really worth doing it (at least reading the first N-1 problems in a N problem set).

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      13 months ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      Looking forward

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      13 months ago, # ^ |
        Vote: I like it +2 Vote: I do not like it

      why doesn't this comment has the number of upvotes it deserves.

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      13 months ago, # ^ |
        Vote: I like it +9 Vote: I do not like it

      Hmm note that testers are usually part of conspiracies. So the N'th problem could be the easiest, we should try to solve that first.

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Looking forward to the contest, hoping to learn some new concepts :)

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Can i become pupil after this round?

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13 months ago, # |
Rev. 2   Vote: I like it 0 Vote: I do not like it

One more new author of div 3 *o*
Hope I become pupil again

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13 months ago, # |
Rev. 2   Vote: I like it +22 Vote: I do not like it

I still remember the time when vovuh was a coordinator of Div3, it has been so long.

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    13 months ago, # ^ |
      Vote: I like it -31 Vote: I do not like it

    *has, try improving your grammar. Would really go a long way in interview preparation.

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      13 months ago, # ^ |
      Rev. 3   Vote: I like it +15 Vote: I do not like it

      try not correcting others' grammar errors. would really go a long way in your interview process if interviewer's grammar isnt that great:)

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13 months ago, # |
  Vote: I like it -60 Vote: I do not like it

please schedule the contest 1 hr earlier as it perfectly ends before dinner and good discussion time before going to sleep

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    13 months ago, # ^ |
      Vote: I like it +21 Vote: I do not like it

    You don't know how many time zones in the world, do you?

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    13 months ago, # ^ |
      Vote: I like it +5 Vote: I do not like it

    This request is the perfect definition for self centered.

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      13 months ago, # ^ |
      Rev. 4   Vote: I like it 0 Vote: I do not like it

      i was not saying to schedule this contest but if possible in future contests if doesn't affect other guys previously some contest were 1 hr earlier which had some comments that's why I thought of sharing thought with community :/ had some personal interest also lol

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13 months ago, # |
  Vote: I like it +3 Vote: I do not like it

Good luck 4 everyone! Have fun

I wish that u'll up your cf rating

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    13 months ago, # ^ |
      Vote: I like it -11 Vote: I do not like it

    Again, that's impossible. If you have good delta you have bad delta. If you have extremely good delta, you have extremely bad delta.

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

very helpful contest for beginners :)

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Ah yes, finally i can reach pupil.

hopefully

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

I can leave a message again Yea~

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13 months ago, # |
  Vote: I like it -15 Vote: I do not like it

can i say that div 3 is the best training contest for who is less than 1600 rating and will be better if problem standard

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13 months ago, # |
  Vote: I like it -32 Vote: I do not like it

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13 months ago, # |
  Vote: I like it +21 Vote: I do not like it

It seems that the queue is really long......Can this round hold on time?

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13 months ago, # |
  Vote: I like it +4 Vote: I do not like it

Verdict: In queue

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13 months ago, # |
  Vote: I like it +8 Vote: I do not like it

There is a problem with submission, it shows the "In Queue" verdict. Wish this will not happen in today's contest.

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13 months ago, # |
  Vote: I like it -10 Vote: I do not like it

i think this div3 round is going to be unrated !! "In queue" fact

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13 months ago, # |
  Vote: I like it +12 Vote: I do not like it

Anyone else getting Bad Gateway errors lately?

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    13 months ago, # ^ |
      Vote: I like it +4 Vote: I do not like it

    Yes, I think there is a server issue on cf.

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    13 months ago, # ^ |
      Vote: I like it +1 Vote: I do not like it

    Hope this won't occur during contest , DIV3s are imp for beginners.

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13 months ago, # |
  Vote: I like it +8 Vote: I do not like it

Notice unusual change in schedule.. :(

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    13 months ago, # ^ |
      Vote: I like it +5 Vote: I do not like it

    I think it's better to have a postponed rated round than an unrated round
    (it doesn't matter to you as it is already unrated for you :D)

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13 months ago, # |
Rev. 2   Vote: I like it 0 Vote: I do not like it

I hope today, there will be no queue in codeforces,

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Delayforces!!! :(

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

It's been an hour since I submitted a problem. Still in queue :(

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    13 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Yes! my submission is also in the queue. :(

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13 months ago, # |
  Vote: I like it +2 Vote: I do not like it

um so how many registrations will this round have now?

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

The least they can do is to reset the participants so that there won't be another 30k contest and it becomes unrated, seems like no one cares about div.3 contests.

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    13 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    What do you mean by no one cares about div.3 contests?

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13 months ago, # |
  Vote: I like it +36 Vote: I do not like it

It's my first time to see a 24-hour delay here.

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

why mike why

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Nooo :((

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Peeporiot ;-;

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13 months ago, # |
  Vote: I like it +15 Vote: I do not like it

Better delay than unrated :(

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13 months ago, # |
  Vote: I like it -13 Vote: I do not like it

:( :( :( I have planned to go to my village tomorrow

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13 months ago, # |
  Vote: I like it +6 Vote: I do not like it

So,30k+ participants this time?

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Delay 1 day ?

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Round postponed

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

round is postponed, I was waiting and refreshing every 1 minute to see how much time left. sad life.

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13 months ago, # |
  Vote: I like it +3 Vote: I do not like it

Since the contest was postponed, can you please open the registration again?

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13 months ago, # |
  Vote: I like it +9 Vote: I do not like it

Div 3 — Let's rock today.

(postponed :{ )-

Let's practice today :}

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13 months ago, # |
  Vote: I like it +11 Vote: I do not like it

due to Internet × wait until the registered participants over 30k √

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13 months ago, # |
  Vote: I like it -60 Vote: I do not like it

I finished my talk over phone with bae just 5 mins before the contest only to know this... (Cry Emoji)

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13 months ago, # |
  Vote: I like it +2 Vote: I do not like it

All this time.. i was refreshing my browser..thinking issue on my side.

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13 months ago, # |
  Vote: I like it -20 Vote: I do not like it

The round has been postponed- NO WORRIES

IPL has been postponed- CRY, CRY, CRY :(

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13 months ago, # |
  Vote: I like it -60 Vote: I do not like it

postponed for 24 hours! I will never participate in a CF contest if this contest has been postponed again!

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13 months ago, # |
Rev. 2   Vote: I like it +3 Vote: I do not like it

Stepavly please enable the register button so that the people who have not registered and are the official trusted participants can register !! ** Thanks in advance ** !!

UPD : THANKS !! I have successfully registered now !

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

when I finish my dinner fast for the contest...

Unfortunately, due to Internet provider network issues, we have to postpone the round

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13 months ago, # |
  Vote: I like it +101 Vote: I do not like it

.
Pics-Art-05-04-08-18-05

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    13 months ago, # ^ |
      Vote: I like it +2 Vote: I do not like it

    you are genius bro!

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    13 months ago, # ^ |
      Vote: I like it +2 Vote: I do not like it

    and then 24 more hours for ratings change. I don't know whats there in calculating ratings that takes 2 or more hours.

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Thanks for changing the time. I was having issue since noon. ( contest starts on my local time at 8:30 pm at night ). m1 m2 and m3 all were down and showing "bad gateway 503", I thought, I wont be able to join the contest due to this network issue. Thanks a lot to the organizer to consider the issue.

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13 months ago, # |
  Vote: I like it +1 Vote: I do not like it

Verdict: No Color! :(

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13 months ago, # |
Rev. 2   Vote: I like it +8 Vote: I do not like it

Cf: Hmm you're mad because we delay the round for 5 min sometimes WEll How About 24 hours !! Muahaha

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13 months ago, # |
  Vote: I like it +2 Vote: I do not like it

Really excited for the contest , hoping I would cross 1100 this time. Any tips are welcomed. TIA

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Hopefully, I become pupil today.

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13 months ago, # |
  Vote: I like it +4 Vote: I do not like it

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13 months ago, # |
  Vote: I like it +1 Vote: I do not like it

Good luck to everyone!

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13 months ago, # |
  Vote: I like it +7 Vote: I do not like it

gM0ZCR.png when you heard the round was delayed

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Did we break a registrants record?

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    13 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    In one of the div3 rounds, there were 30k+ registrations. Unfortunately round went unrated due to long queue

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      13 months ago, # ^ |
        Vote: I like it -13 Vote: I do not like it

      that is why they shoudnt allow >1600 to submit during the contests..so as to reduce the queue..almost 2000 are there ....this should run properly...only once in a month...div3

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

This will be my second contest. I participated in last global round and I still don't know how the score works perfectly. In that contest I think they gave me less points for a problem with previous wrong submissions. Here when it says there's a 10 minutes penalty for wrong submission, is it saying that I will lose 10 minutes from the total 2 hours of the contest for every wrong answer?

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    13 months ago, # ^ |
      Vote: I like it +4 Vote: I do not like it

    You are judged by number of solved problems, and penalty points. Foreach AC submission you get 1 solved problem, and the number of minutes from start of contest plus 10 minutes per wrong submission of that problem as penalty.

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      13 months ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      Thank you. I thought it meant I would have less time to solve problems, misunderstood that

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13 months ago, # |
  Vote: I like it -29 Vote: I do not like it

I have -3 Contribute, please upvote for me :((

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13 months ago, # |
  Vote: I like it +1 Vote: I do not like it

i have a feeling that site may crash !!!!!

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13 months ago, # |
Rev. 2   Vote: I like it 0 Vote: I do not like it

Hemlo Joshi(cout_wolf) dear!!!

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Hope minimum FSTs....

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Why on equal rank in div3 contest gives less positive delta then div2 on same rank. Suppose x rank in div3 will give less positive delta than x rank in div2 ?

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    13 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    coz having the same rank in a more difficult contest(since better rated participants are rated in Div2 contests, than in Div3) is better.

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      13 months ago, # ^ |
        Vote: I like it +1 Vote: I do not like it

      So , greater number of participation theory fails here!

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13 months ago, # |
  Vote: I like it +7 Vote: I do not like it

Hope the contests won't get unrated because of long queue, we are reaching close to 30k , at this rate we might be reaching around 32k easily

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    13 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    Registered people might not give contest today!

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    13 months ago, # ^ |
      Vote: I like it -11 Vote: I do not like it

    Round got ruined due to long queues. :/ Submitted a solution in the last 20 seconds, site kept loading till the contest ended. Solution didn't get submitted before that due to queue. But it got AC after the contest. I dunno if Mike can do something about it or whether I am set to lose points for that solution. Sed life!

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13 months ago, # |
Rev. 2   Vote: I like it 0 Vote: I do not like it

Got It.

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    13 months ago, # ^ |
      Vote: I like it +2 Vote: I do not like it

    no score distribution in div3

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13 months ago, # |
Rev. 3   Vote: I like it 0 Vote: I do not like it

It's starting finally: the most awaited contest since yesterday :)

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

Cheers Codeforces for 30K registrations once again!!!

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13 months ago, # |
  Vote: I like it -15 Vote: I do not like it

30k registrations aaj lgega queue :(

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

It is 30000+ contestants today. I hope CF doesn't crumble :(

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13 months ago, # |
  Vote: I like it +6 Vote: I do not like it

my code is running from more than 10 min, i also tried to cout<<"HELLO"; but it also taking more than 10 min ; MY internet connectivity is good. i also tried to logout and log in

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13 months ago, # |
  Vote: I like it +1 Vote: I do not like it

Is there any queue issue :( , my code is in the queue for last 20 minutes

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13 months ago, # |
  Vote: I like it +4 Vote: I do not like it

It seems that my submission for G is executed twice, is this right...?

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13 months ago, # |
  Vote: I like it +8 Vote: I do not like it

you guys should give atleast some weight to out-of-contest submissions. It's not like everyone participates in div3 :|

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13 months ago, # |
Rev. 5   Vote: I like it 0 Vote: I do not like it

;

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13 months ago, # |
  Vote: I like it -38 Vote: I do not like it

THE QUEUE IS TOOOOOOO LONG I CANT STAND IT PLEASE MAKE IT UNRATED

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

After waiting for 4-5 minutes.

WA on test 1

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13 months ago, # |
  Vote: I like it -15 Vote: I do not like it

Queueforces :(

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

questions were very interesting but the long queue snatched away all the fun :(

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13 months ago, # |
  Vote: I like it -21 Vote: I do not like it

Make this round unrated. Continuous 5 minute queue isn't suitable thing to run a rated round

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13 months ago, # |
  Vote: I like it 0 Vote: I do not like it

That "In Queue" annoys me a lot!! Ruined my contest.

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13 months ago, # |
  Vote: I like it -19 Vote: I do not like it

No way this can be rated!

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13 months ago, # |
  Vote: I like it +60 Vote: I do not like it

Interactive is not good when long queue time is there.

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13 months ago, # |
  Vote: I like it +30 Vote: I do not like it

This Contest should have been extended by 15-20 min to compensate for long queue

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    13 months ago, # ^ |
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    what if some people have work after it ? Extending round is always a bad idea. They can keep it for 15-20 min extra but it should be announced before the contest. for majority of people queue time didn't matter much and it was fair for everyone since everything was same for everyone.

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      13 months ago, # ^ |
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      Actually, there have been situations in which the contest was extended due to long queue. I think it wasn't a really smart choice to put >100 cases in G considering that both F1 and F2 were interactive, though.

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      13 months ago, # ^ |
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      I agree that people may have other commitments after the contest but extension has been done many times during some the previous Div 3 Rounds and extension gives relief in some sense . if you have another work just go for it , there will always be some contest in a week after it so you can make a comeback in it to recover your rating loss

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13 months ago, # |
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I am eagerly waiting to see test case 5 of problem "D".

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    13 months ago, # ^ |
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    Maybe you did not use long long!

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    13 months ago, # ^ |
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    For me the trick was storing the frequency of the difference as long long.

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    13 months ago, # ^ |
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    I got wrong on test 5, then I changed my min=1e18 and it got accepted... :)

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    13 months ago, # ^ |
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    it's because u didn't use int64_t or longlong. The test case made the answer greater than the limit of 32 bit integer. I guess your logic is totally correct but just didn't use the correct datatype.

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13 months ago, # |
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C,D<A<<B<<<E,F1<<<<<F2<<<<<<<<<<<G I know the number of solves indicate otherwise (difficulty distribution linear from A to G) But just look at the number of wrong answers and solution size.

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13 months ago, # |
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Can someone confirm if problem G was dijkstra ? I just submitted it and excited if my approach is correct.

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    13 months ago, # ^ |
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    No. Brute force Dijkstra should TLE because the complexity is of the order $$$\mathcal{O}(E(G)) \sim 10^{12}$$$

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      13 months ago, # ^ |
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      dijkstra is O(ElogV) and not O(EG) if you use min priority queue

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        13 months ago, # ^ |
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        How is $$$E(G)$$$ not $$$10^{12}$$$? If you directly bruteforce from each teleporter you have $$$mn \sim 10^6$$$ edges from each node and so it behaves like Dijkstra on a complete graph which obviously exceeds time limits. I just dropped the $$$\log V(G)$$$ factor because removing that doesn't make my argument fail.

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          13 months ago, # ^ |
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          there is actually a better way to do this, you can add a dummy node to which you connect all teleporters (from), and then you connect the dummy node to all teleporters (to). So in this Case you only have O(E) edges

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            13 months ago, # ^ |
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            Sorry, but I don't see how that's an improvement in the complexity.

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              13 months ago, # ^ |
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              Like floki said, each cell has 4 edges going out of it (up, down, left, right), but also for each teleporter you add an additional edge to a dummy node (at most $$$nm$$$ more edges), and an edge from the dummy node to each teleporter (at most $$$nm$$$ more edges). So the total number of edges is at most $$$6nm$$$, which is reasonable but still hard to get to pass on this problem.

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13 months ago, # |
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Google-forces

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13 months ago, # |
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So, I waited 10 minutes to get a TLE on test 114 of G after the contest had ended already . LOL

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13 months ago, # |
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Literally I spent 8 minutes to get Wrong answer on pretest 4

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13 months ago, # |
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    13 months ago, # ^ |
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    How do you guys get so much time to find similar problem in google during the contest!

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      13 months ago, # ^ |
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      Actually I didn't search I knew I had done it before

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      13 months ago, # ^ |
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      A lot of people prioritize searching on Google over thinking about it themselves. You know, just in case, they don't even have to solve it themselves. Just yoink the already written code by someone else, and boom Positive delta.

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13 months ago, # |
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SlowForces

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13 months ago, # |
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Waiting for this comment. In queue

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13 months ago, # |
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WHAT A BAD ROUND!I must wait 8 minutes for the result of my submission.

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    13 months ago, # ^ |
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    yes and because of that couldn't make changes in ans if it was wrong...literally 2 hrs passed so fast.

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13 months ago, # |
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The queue was so much annoying !

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13 months ago, # |
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I remember getting up for Kickstart round H last year, quite early in the morning, I think it was worth getting up. But not on that that day, its today, cuz problem E is literally this lol. Also Thanks to people like Galen, Ecnerwala, Neal, who posted solution to (problem E) that round that day. High rated people do have time machine xD.

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13 months ago, # |
  Vote: I like it +65 Vote: I do not like it

F2 was an absolute bomb. It's been a while that I see such a beautiful problem.

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    13 months ago, # ^ |
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    Agreed, the rest of the problems felt very standard and paled in comparison to F2.

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    13 months ago, # ^ |
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    Depends on your solution... Mine was using something like SQRT decomposition and was really boring. But the intended soln is indeed beautiful.

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13 months ago, # |
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Hey Stepavly, MikeMirzayanov

I submitted problem-A in last 19 seconds but the CF website just kept loading and loading. The time got up, contest ended and my solution couldn't be submitted. How would you take this into account?

UPD: Submitted just now again and it got AC. Here it is 115328838

Would I gain no points for this? :'(

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13 months ago, # |
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Bad internet situation.

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13 months ago, # |
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I submitted no. (D.same difference) before the contest ended. But it is still in the queue. Will it be counted?

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13 months ago, # |
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I forgot to delete a part of my code in F1 that I used to verify my solution, but since I was still in the queue I did not realize it, I feel very bad :(

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    13 months ago, # ^ |
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    same here i also face same problem in c i printed NO instead -1 :( when i realize contest is over :-(

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      13 months ago, # ^ |
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      yes, and the worst thing is that my solution was correct :(

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        13 months ago, # ^ |
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        mine too (you can verify)

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13 months ago, # |
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Can anyone explain problem F2 and G?

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    13 months ago, # ^ |
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    F2: You can query each prefix of the array with step of 8 (that is, 1, 9, 17, ...) and store the number of zeros in it. Now to answer the query, you must first binary-search these prefixes (takes 0 queries), and then search among the remaining 8 elements using exactly 3 queries. Now what happens when we change some 0 to 1? Some suffix of our array with prefixes has to be decreased by 1. To perform these operations quickly, you could use a segment tree. BIT and sqrt decomposition should also work.

    The total number of queries is t*3+n/8 ~ 5,5*10^4 < 6*10^4

    IDK if this solution is the same as the author's one, but this one seems really beautiful to me.

    G: Notice that you either don't use the portals at all or use them exactly once (since we can omit the intermediate steps). The variant without portals is solved using trivial BFS. About the case with portals: you first go from (1, 1) to a portal, then pay its cost, then the cost of the second portal, and then you go from portal 2 to the end. You can compute these sum of the portal's cost and the cost to go to this portal from (1, 1) and select the one which minimizes this quantity as the first one. The case with the second portal is symmetric.

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      13 months ago, # ^ |
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      For F2, you can break the interval into blocks of size 32 ([1,32], [33,64], ...) and query the number of 0s in each of them. This takes roughly 2*10^5/32 = 6250 queries. Then you can answer each k by finding its appropriate block and binary searching on it.

      Each answer will require 5 queries, so we use at most 5*10^4+6250=56250<6*10^4 queries.

      The advantage of using blocks instead of prefixes is that we only need to update a single block after each answer. Also, since we chose a block size of 32, we can directly iterate to find the block that will contain the answer (since 10^4*2*10^5/32 = 6.25*10^7).

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      13 months ago, # ^ |
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      My sqrt decomposition solution of F2 is giving wrong answer on test case 21 (queries limit exceeded). has anyone done using sqrt decomposition

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        13 months ago, # ^ |
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        for me, taking block size as $$$n^.5$$$ failed on TC 21, but taking block size as $$$n^.25$$$ worked.

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        13 months ago, # ^ |
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        Taking block of sqrt(n) will not pass. In worst case with block size of n^0.5 length will be 450 and log of 450 is 8.8 ~ 9. so for 10^4 tests atleast 9*10^4 queries will be made.

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      13 months ago, # ^ |
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      It's helpful. Thanks !!

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    13 months ago, # ^ |
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    For G using k+1 portals is never more optimal than using k portals. Hence we shall use either 0 or 1 portal. let cost[i][j] = minimum cost to move from [i,j] to n,m using only adjacent moves. Now for each portal do cost[i][j] += matrix[i][j] and find the minimum cost to travel from a portal to n,m. Let this value be equal to min_cost.Now the answer to the problem would be minimum cost to reach from a portal [i,j] to [1,1] + min_cost + matrix[i][j]. Which is equivalent to moving from [1,1] -> p1 -> p2 -> [n,m]. Dont forget the case when you use 0 portals.

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13 months ago, # |
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must be unrated i waited so long for in queue

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13 months ago, # |
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Please make this round unrated. Couldn't solve the problems on time due to the waiting thing.

It took 10 mins to get the final verdict to one submission.

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    13 months ago, # ^ |
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    Absolute right. only because of this i couldn't try F1 in last minutes.

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13 months ago, # |
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Please do something about "**In Queue**" while submitting in the contest. It always gets stuck in the middle of contest.

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13 months ago, # |
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Regardless of whether you are a trusted participant of the third division or not, if your rating is less than 1600 or greater than 1600 or even equal, then the round will be un-rated for you.

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13 months ago, # |
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Someone confirm I'm not blind, this was the sample shown for problem F2: Image please load

So this seems to imply that you have to read in a 0 after each test case, which is a thing that some interactive problems make you do. But not this problem. When I tried to read in 0, I got runtime error on test 1, and removing that worked. So did the samples lie to me?

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13 months ago, # |
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There should've been extra 10-15 minutes for such a long queue!

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13 months ago, # |
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Site was down for the last few minutes.

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13 months ago, # |
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    13 months ago, # ^ |
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    Did you find all of them during contest ?

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      13 months ago, # ^ |
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      I checked his profile, doesn't seems he attended the contest.

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    13 months ago, # ^ |
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    Solving problems is faster and exciting then finding it on google! :)

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      13 months ago, # ^ |
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      Exciting- Very true
      But any regular CP-er has already practiced these common problems and knows where they can be exactly found.

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        13 months ago, # ^ |
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        That's our weakness that we didn't practice those problems. Right? :)

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          13 months ago, # ^ |
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          I never said weakness. You solve the problems during the contest, kudos to you. I have attended every contest of codeforces and leetcode from the past 1.5 years (not from this account) and have practiced these problems more than 7-8 times, which doesn't make for me to again write the same code.

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        13 months ago, # ^ |
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        They paracticed those similar problems erarlier so they had more knowledge than u, thats why they solved those because they can relate those idea with the given problems. Not necessarily to searching and copying everything from google

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    13 months ago, # ^ |
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    If you have already seen those problems somewhere before then gj here's a candy

    Let us (newbies) enjoy those quality problems.

    also imo, adding classical problems in a div3 is actually a good idea as they are hosted to improve your skill not the ratings

    but hey! you can switch the platform whenever you feel like ;)

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    13 months ago, # ^ |
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13 months ago, # |
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The queue sucked. This round should be unrated!

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13 months ago, # |
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Started the contest 15 minutes late, but still managed to get till F1 in 1 hr 30 minutes. My best performance so far, thanks for the round and hope it remains rated.

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    13 months ago, # ^ |
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    " Started the contest 15 minutes late "

    lol, you made 2 submissions before starting, thats so cool!!

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      13 months ago, # ^ |
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      I count starting the contest when I get first AC, this way it keeps me motivated even if it takes 1 hr to solve A lol.

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13 months ago, # |
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Anybody else think that solutions should be regraded for problem G with an easier time constraint? Maybe it's just java idk :P

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13 months ago, # |
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editorials??

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13 months ago, # |
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Can someone tell me whats wrong in this code 115328097

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    13 months ago, # ^ |
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    answer can be greater than INT_MAX. initializing mini with some bigger value should work.

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13 months ago, # |
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If long queue would not have been there then I could have got F1 and F2 right in time.

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13 months ago, # |
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Did someone got G?? I got WA on test-26

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13 months ago, # |
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can someone tell me why i got TLE PLEASE for(int i=0;i<n;i++){cin>> a[i];

if(a[i]>=i){  x=hashmap[a[i]-i];count+=x;

hashmap[a[i]-i]++; }

else if(a[i]<i){ x=neg[i-a[i]];count+=x;
neg[i-a[i]]++; }

}

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13 months ago, # |
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At least there should have been a 10/15mins extension of contest duration was needed due to the long queue problem. I just needed to change the answer from int to long long to get problem E AC. :(

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13 months ago, # |
Rev. 4   Vote: I like it 0 Vote: I do not like it

This comment is deleted , {how to delete a comment ??}

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13 months ago, # |
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I'm so stupid!!! I used INT_MAX as infinity value in problem E :(

wrong ans on test 5
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13 months ago, # |
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too many copy-paste problem :(

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    13 months ago, # ^ |
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    That's unfortunate. I solved till E and all by myself and I was so proud of my approach to E, but now since I found out that it was on the internet, I feel cheated :)

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      13 months ago, # ^ |
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      its not the point bro. the point is that you should have faith in yourself, don't cheat yourself, and give your best in contests.

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13 months ago, # |
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Did anyone else get WA on test case 37 for G? My submission if anyone wants to check it out.

My approach:

Do Dijkstra's algorithm, and find the shortest path to enter a portal (call it $$$P$$$). Then, run a multi-source Dijkstra's, with each source being a portal, and the starting distance to the portal as $$$P$$$.

In my code, the priority_queue stores <-distance, pii{i, j}>, and the distance is stored as negative, because Dijkstra's uses a min heap, while the default priority_queue<> uses a max heap.

The dijkstra lambda function is just so that I don't need to copy-paste the code.

The portal variable stores the shortest distance to a portal.

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13 months ago, # |
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Me after giving this contest -> https://www.youtube.com/watch?v=Uz-sPvopjvY

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13 months ago, # |
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Weak test cases for problem D. Disappointed :|

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13 months ago, # |
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Nice problems, but really bad problem statement in F, especially F2, description is hardly understandable, and description of input simply wrong.

I am shown as +100, but would rather see it if it were unrated.

Also the queue was slow.

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    13 months ago, # ^ |
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    How to check expected rating change before official changes ??

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      13 months ago, # ^ |
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      download an extension

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        13 months ago, # ^ |
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        which extension?

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          13 months ago, # ^ |
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          It is called "CF-Predictor", should be available by google search.

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        13 months ago, # ^ |
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        I use Carrot, and it works really well. Idk why it's named "Carrot" though lol

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          13 months ago, # ^ |
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          Carrot is better than cf-predictor... (i used both)

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    13 months ago, # ^ |
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    Totally agree about F2

    It is rather confusing to say the least

    First there are too many letters to be easily comprehended. But that's not the only problem

    For example at some point they talk about "requests", then there are "queries". You would think it is different things,

    Then right after the description of the output format there is "In case of an incorrect query, -1 will be displayed" and you try to match with the format, thinking that maybe you need to read some confirmation code after you cout the answer because it is natural to think outputing the answer is a kind of query

    Finally there is brilliant statement "Then t lines follow, each of which contains one integer k". I don't know about others but for me it means that at this point I can read t lines.

    Yes, it is possible to figure out what was meant by rereading the samples and 1KB statement a few times or by requesting clarificiation, but I find it rather inconvenient. It is especially inconvenient when the server barely works.

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13 months ago, # |
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Can someone please help, why is this giving TLE in test 3 ? 115323338 , 1520F2 - Guess the K-th Zero (Hard version) Thanks ! UPD: I got it, since I used RUPQ Fenwick tree I forgot to update(r+1,-v) when I update(r,v)

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13 months ago, # |
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Not only the blog was almost-copy-pasted-part. But also the problems. Idk what did the testers do really test. And did not report for such well known problems.

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13 months ago, # |
  Vote: I like it +4 Vote: I do not like it

I've just started getting the knack of codeforces. And I was able to solve A, B, C, D in this contest. But I was slow to think of the approaches and hence my rank is around 6k. Hopefully, I will get better at thinking fast about the solutions. If any tips that may help, please do tell me cause that would be great.

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    13 months ago, # ^ |
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    Practice

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    13 months ago, # ^ |
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    What helps me to solve problems faster is to get better at math, especially competitive math, because the easier math problems have similar styles to the first few problems in a Div3 or Div2. Also, solving Codeforces Div3's and Atcoder abc's (Atcoder Beginner Contest) was one of the biggest factors in my speed. Now I just need to improve on actually getting the solutions...

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13 months ago, # |
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how to solve F1?

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    13 months ago, # ^ |
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    Binary search the answer. Let's say you know sum(1,cur), then if cur-sum(1,cur) (which is the number of zeroes in that range) is greater than or equal to k then you know that the kth zero should be in the range [1;cur]. Else if n-sum(1,cur)<k then the kth zero is in the range ]cur;n]. So binary search over cur. 115289534 PS: sorry for not using LATEX

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    13 months ago, # ^ |
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13 months ago, # |
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Problem D Video Editorial (in Detail Explanation) : https://youtu.be/7IRsFvqgWlw

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13 months ago, # |
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I was facing huge network delay during the contest . every question took around 5 minutes just to submit . Was anyone else facing this issue ?

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13 months ago, # |
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What is the intended solution for F2???

It seems that the author's solution is just do binary search every time and avoid query one segment twice.

But there's another very beautiful solution that divides $$$1$$$ to $$$n$$$ into blocks of $$$8$$$ and use data structures to maintain.

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    13 months ago, # ^ |
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    What is this technique of division to 8 blocks called?

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      13 months ago, # ^ |
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      It's not a common technique.

      That solution is only used for F2