PrinceOfPersia's blog

Codeforces Round #406
By PrinceOfPersia, history, 8 years ago, In English

Hello Codeforces, and happy Nowruz.

It's an honor to announce you that Codeforces Round #406 is going to take place on March 23rd.

I'm the writer of this round and it is gonna be my 6th CF contest (there are still plenty coming...). There are 5 problems and you'll have 120 minutes to solve them.

I'd like to thank keyvankhademi and waterfalls for testing this round, netman and KAN for helping me prepare this round and MikeMirzayanov for awesome platforms of Codeforces and Polygon.

The main characters of this round are going to be Rick and Morty!!!

Scoring will be posted soon.

Problems are sorted by their expected difficulty, but I strictly recommend you to read all the problems.

GL & HF!

P.S: Top IOI 2017 participant in each division (only with handle present in the future IOI handle list) will be rewarded with special Persian souvenirs in Tehran.

UPD: Scoring distribution is: 500, 1000, 1750, 2000, 2500 for Div.2 and 750, 1000, 1500, 2000, 2500 for Div.1

UPD: Editorial is out!

UPD: System test is over, congratulations to the winners.

Div.1 winners are:

  1. jqdai0815
  2. Um_nik
  3. LHiC
  4. -XraY-
  5. ershov.stanislav

Div.2 winners are:

  1. xumingkuan
  2. HXLLL
  3. Rpd-Strike
  4. U6121071173
  5. Khismet

See you next time ;)

  • Vote: I like it
  • +493
  • Vote: I do not like it

Comments Comments (219)
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8 years ago, # |
  Vote: I like it +86 Vote: I do not like it

amd is back! <3

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    8 years ago, # ^ |
    ← Rev. 2   Vote: I like it +79 Vote: I do not like it

    AMD is an absolute champ in preparing nice interesting and original problems.

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8 years ago, # |
  Vote: I like it +20 Vote: I do not like it

Amd's contests are so good. I've never been disappointed with any of his contests. Looking forward to this Thursday.

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

are you sure then IOI participants has in EACH division?

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

    You would be surprised, but as far as I remember the split was 50 / 50 for those with a Codeforces account.

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8 years ago, # |
← Rev. 2   Vote: I like it +5 Vote: I do not like it

"I strictly recommend you to read all the problems" does that related to the difficulty of the upcoming problems???

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    8 years ago, # ^ |
      Vote: I like it +5 Vote: I do not like it

    read this

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    8 years ago, # ^ |
      Vote: I like it -15 Vote: I do not like it

    From quite an experience , I believe , the statement wants to convey that C can might turn out to be easier than B :P

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    8 years ago, # ^ |
      Vote: I like it +17 Vote: I do not like it

    For example, you are very good at math and E is math problem which you can solve, but you are solving A-B-C and can't solve D, so you can think if I can't solve D, I won't solve E too and don't reading problem. So, it is good to read all the problems.

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8 years ago, # |
  Vote: I like it +54 Vote: I do not like it

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    8 years ago, # ^ |
      Vote: I like it +8 Vote: I do not like it

    Will be using this when code fails system tests :(

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8 years ago, # |
  Vote: I like it +19 Vote: I do not like it

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8 years ago, # |
  Vote: I like it +21 Vote: I do not like it

Happy Nowruz! I wish everyone that the round was truly festive!

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

I missed PrinceOfPersia's rounds so much!

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

(only with handle present in the future IOI handle list). Where's that list?

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8 years ago, # |
← Rev. 2   Vote: I like it -25 Vote: I do not like it

Problems are sorted by their expected difficulty, but I strictly recommend you to read all the problems.

GL & HF!

// What's the output of this code ? :)

cout<<(GL=="Good Luck" && HF == "Have Fun" ? "Yes":"No");
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8 years ago, # |
  Vote: I like it 0 Vote: I do not like it

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8 years ago, # |
  Vote: I like it +74 Vote: I do not like it

"Do ya hear that M-M-Morty? *URP* We're gonna go to a universe where everyone is a character in a programming competition, Morty--"
"I-I, uh, I don't know Rick, that sounds like--"
"A programming competion, Morty! Codeforces, Morty!"

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

Hope morty doesn't go back to the old shop... :/

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8 years ago, # |
  Vote: I like it +48 Vote: I do not like it

Good Luck and Have Fun !!

I hope this comment becomes the reference for all authors who are lazy to write it , and they write GL or HF . so they can copy paste it from here .

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8 years ago, # |
  Vote: I like it -10 Vote: I do not like it

First of all I apologise to write it here as I am very much new to this.I want to hack a problem which is already accepted.But I can see that the solution is wrong,what to do,Please Help.

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

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8 years ago, # |
← Rev. 2   Vote: I like it -8 Vote: I do not like it

AMD setting the round + Main characters as Rick and Morty. This is going to be good.

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

    do not be so sure until you see the mromlems

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

A contest about me? thx :D

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8 years ago, # |
  Vote: I like it -18 Vote: I do not like it

wowwww im very much excited about the contest ... for giving this contest i will eatless :) hoping for +ve rating change and i love all the contest prepared by PrinceOfPersia ... and i love him too :) his style of blog writing is awesome and he is also awesome... i love codeforces ,,,,, i love MikeMirzayanov and i love alll :) happy coding best of luck for the contest :D

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8 years ago, # |
  Vote: I like it +55 Vote: I do not like it

What made you change your mind?

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

I just love codeforces contests

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

Best theme ever! This is one of the main reasons for why I love competitive programming...

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8 years ago, # |
  Vote: I like it +41 Vote: I do not like it

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

..

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

Why the hell your characters are soooooooooooooo intresting?! 1-Barney Stinson 2-Mike 3-Rick and Morty all of them are wonderful

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8 years ago, # |
  Vote: I like it -19 Vote: I do not like it

can someone tell me the full-form of amd please?

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

Do i only see that i have last 2nd contest's amount of points instead of amout that should i have now? I mean i have 1021 when i had after last round 1087 and i see everybody have the same issue

Also my submissions from last contest got back themselves

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8 years ago, # |
  Vote: I like it +25 Vote: I do not like it

Glad to see my teacher is holding another round, good luck PrinceOfPersia (reply to this comment).

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

Happy Nowruz everyone) Hope that most will increase their rank

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8 years ago, # |
  Vote: I like it -49 Vote: I do not like it

Everybody, who liked this commend will increase his rating))

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    8 years ago, # ^ |
      Vote: I like it +133 Vote: I do not like it

    *no one upvotes and thus your statement is true*

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8 years ago, # |
  Vote: I like it +14 Vote: I do not like it

Good thing CodeForces doesn't have verdict "Not Acceptable", else this round will be full of Error 406: Not Acceptable.

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8 years ago, # |
  Vote: I like it +43 Vote: I do not like it

It's my birthday contest !! thanks PrinceOfPersia :D

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8 years ago, # |
  Vote: I like it +173 Vote: I do not like it

Guys, better prepare robust version of Heavy-Light Decomposition. Afair on 3 out of 5 PrinceOfPersia's contests E required it xD.

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    8 years ago, # ^ |
      Vote: I like it +48 Vote: I do not like it

    Thanks, I will Unregister!!!

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      8 years ago, # ^ |
        Vote: I like it +232 Vote: I do not like it

      Yeah, possibility of Div1E being HLD is a perfectly valid reason for greens to unregister ;p.

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        8 years ago, # ^ |
        ← Rev. 5   Vote: I like it +35 Vote: I do not like it

        I understand Sarcasm.Thanks

        If E is HLD,then Accordingly all lower problems like D will be of PersistenSe segTree amd c will be of Sqrt decomposition and b will be of Dynamic programming with bitmasking and A will be of Maximal fLow and minimum cut in graph and Div2B will be from suffix trie and then DIV2a will be Unknown theorems on NUmber theory .So,I said I will Unregister

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          8 years ago, # ^ |
            Vote: I like it +144 Vote: I do not like it

          If E is HLD,then Accordingly all lower problems like D will be of PersistenSe segTree amd c will be of Sqrt decomposition and b will be of Dynamic programming with bitmasking and A will be of Maximal fLow and minimum cut in graph and Div2B will be from suffix trie and then DIV2a will be Unknown theorems on NUmber theory .

          That's a pretty good and valid point.

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    8 years ago, # ^ |
      Vote: I like it +50 Vote: I do not like it

    Funny fact: in Round #362 problem E was not a hardest problem, but it was indeed a HLD-problem. So, if a problem on HLD appears, it will apparently be the problem E, no matter how many problems in the contest there are.

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      8 years ago, # ^ |
        Vote: I like it +46 Vote: I do not like it

      On last Petrozavodsk I used HLD once and it was also problem E (E2) :D. Apparently it was second easiest problem that day xD.

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8 years ago, # |
  Vote: I like it -144 Vote: I do not like it

who likes inception?

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8 years ago, # |
  Vote: I like it -162 Vote: I do not like it

fact : PrinceOfPersia is a gay prince and he's trans.

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    8 years ago, # ^ |
      Vote: I like it -24 Vote: I do not like it

    So?

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

      Amirp78 the only thing we all know here is sir PrinceOfPersia is a great coder and motivation of all of us . His problemsetting is awesome :) and his contest are always interesting , so focus on that fact !!! :)

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8 years ago, # |
  Vote: I like it -33 Vote: I do not like it

Hi, Prince)

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

mrims of persia always very nice mromlems, looking forward to the round 406, good luck

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8 years ago, # |
  Vote: I like it -28 Vote: I do not like it

Me when the competition starts (better watch out!)

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

Scoring distribution?

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

I didn't know the theme was Eminem too

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8 years ago, # |
  Vote: I like it +6 Vote: I do not like it

Hacking page does not load.

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

EM fan eh ?

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8 years ago, # |
  Vote: I like it +26 Vote: I do not like it

Did anybody notice the names of the problems...they are the names of eminem's songs too.

Nice taste PrinceOfPersia.

:)

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

Very long queues.

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

Is there a long hack queue? My hack has been in queue for almost 5 minutes now

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8 years ago, # |
  Vote: I like it +69 Vote: I do not like it

This is exactly how I read the problem statements to understand the whole meanings.

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

If suppose somebody program is write but would terminate before considering all the inputs would it be a valid program or not?

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

    All that matters is that your output is correct, it is not necessary to take the entire input.

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

It could be better if there were explanations for the examples in Div 2 problem C. It is possible to understand it ambiguously.

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

Systests of A will make many people sad (me too) :'(

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8 years ago, # |
  Vote: I like it +34 Vote: I do not like it

Like almost everyone after the contest

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8 years ago, # |
  Vote: I like it +35 Vote: I do not like it

Div 2 B and C are so ambiguous. There should be more explanation rather than what we had.

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8 years ago, # |
  Vote: I like it -15 Vote: I do not like it

I do really like problem C xD good job PrinceOfPersia

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8 years ago, # |
  Vote: I like it +83 Vote: I do not like it

PrinceOfPersia right now.

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

How to solve C? My idea is to do dynamic programming with 3 state [position][cycle_passed][turn], with O(k) transition. This gives the right answer, however since cycle_passed could exceed 70, my solution got TLE. Am I on the right track here?

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

    It needs only position and turn(0 or 1), nothing else.

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    8 years ago, # ^ |
      Vote: I like it +5 Vote: I do not like it

    I used a dp approach too, conf[player][pos] = 1 if player can win if he moves first from pos, 2 if he loses, 0 if it-s a loop. I made a dfs(player,pos) to find the answer for the current configuration but I'm not sure it will pass the main tests because of the complexity . It became a little complicated when taking care of the loops so I had to use some extra time to verify those.

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

What are the hack cases for problem 2 divB

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8 years ago, # |
  Vote: I like it +10 Vote: I do not like it

Applause Great problems! Thank you, man!

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

on div2b, why no runtime error for negative values on this solution?

Unsuccessful Hack case

10000 2
8 1 -1 -1000 -2000 -3000 -4000 -5000 -6000
8 1 -1 -1000 -2000 -3000 -4000 -5000 -7000

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

    Could you show the whole code?

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

      sure: submission

      it received WA on systest, but I was wondering why the hack didn't pass

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

        If you add cout << ok << " " << v << endl; to the beginning of code: You get 0x554ae0 0x4f3040. That means that ok was placed after v (exactly v + 100008 = ok), so in fact ok[-1000] makes sense because it means v[100008 - 1000] (Don't have any idea why 100008 and not 100005, that's some compiler stuff).

        But generally you could get a Succesful hack by this test:

        10000 2
3 1 -1 -10
1 10

        He wouldn't clear ok[10] after first group, so he will say "NO" after checking 2nd group and finding that there are two elements with absolute value of 10. But right answer is of course "YES".

        Also this code doesn't check multiple occurrences of the same element. So

        1 1
2 1 1

        will also have "NO" answer, but the right answer is "YES".

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

          I see, so it doesn't give RE only because that memory region is luckily located within the program scope. Well, at least it didn't pass the systest. Thanks for the clarification, it was very helpful!

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

Whats the hack for div 2 A?

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

10000 1 2 -3 -3

So many fell to this single test in div 2 B :-P..

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

Was it possible to solve Div2.D on Python? I tried all my best, and solution is very simple, but Timeout on pretest 8...

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8 years ago, # |
  Vote: I like it +171 Vote: I do not like it

I couldn't really understand the statements. I read problem A like 5 times.

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

    i read it like 20 times til i understand it

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

    I can't still figure out what I should do. Can somebody explain the statement to me? TT

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

      they are moving the same monster alternatively, I read it more than 10 time to figure that out :(

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

      in simplified version, you and i takes turn alternately and choose some number from our set

      my set = {4,3} your set = {2,5,3}

      let x be the initial position of the monster and i were about to move first

      your task is not to make the monster went to the blackhole, and my task is to do so. for example N = 5 and x = 2, and i choose to move 4 steps ahead which makes the x = 1 (circular) then i win, in other case i can move 3 steps which makes the x = 5 and you takes the turn to make sure i can't make the monster into the blackhole

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

      Well you have an infinite game, you have a position and turn. In your turn you take any of your numbers and change position into (position + chosen_number) % n. If you got into 0 -- you win.

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

I think problem E was just a persistent segment tree .Let A be the original array. Make a persistent segment tree B such that position j of the i'th version is 1 if there is no value equal to A[j] between A[i],A[i+1],....,A[j-1]. Once we have this we can do a greedy construction, because we can find the farthest possible endpoint for the next segment in time log(n).

Is this the intended solution?

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

B was easier than A

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

    B was not easier, A was tricky.

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    8 years ago, # ^ |
      Vote: I like it -8 Vote: I do not like it

    I don't think so seeing the number of WAs :P

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

      I thought this before seeing the main tests. After seeing the main test... well things changed.

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

Just 10 more seconds ... (and a faster Internet)

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

Pretty nice contest (although I failed).

B was really nice but I didn't like A.

On C can I coded a solution (which I thought was and I still think so) the idea was that you change the answer at most when you change the K. Also the answers are decreasing so we can do a divide and conquer with at most times computing/doing the O(N) solution for fixed K. Can someone provide a test case which fails that, because it TLEd?

Also how to solve D?

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

Is O(n * log23(n)) the intended complexity for C?

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

    Nope

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

      Then can you give me some hint how to improve this? I used binary search + Persistent IT.

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

        Greedily do for K = 1 — 1000 in O(n). Now notice that for K > 1000, answer will be <= 100.

        Binary search on the range to get answers that lie b/w x for x from 100 to 1.

        For a single x it will take at max O(logn*100*logn*logn) This passes for me in < 1 sec

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

          Yes I done on the similar way.

          First I found article where I read problem with amount of distinct numbers online in O(log n) per query and used existing code. Saw it is not enough to pass testcases, so I calculated first sqrt(N) values before binary search :)

          Other time at the round I spent in reading first problem :D

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

    my solution is n^2, although I don't know if it a solution quite yet.

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

    I got TL8 with O(n log^3 n)

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8 years ago, # |
  Vote: I like it +16 Vote: I do not like it

i think it was very hard round for DIV2 , am i right or not ?

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

I tried div1 C O(n * sqrt(n)) but it has TLE. Hahaha....

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8 years ago, # |
  Vote: I like it +86 Vote: I do not like it

I hope 2*10^4 dfs in problem D will fail? In other case I don't understand why it's D. I decided to look at the submitted solutions and it made me sad.

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    8 years ago, # ^ |
      Vote: I like it +117 Vote: I do not like it

    6848 ms!!! Great! Awesome problem...

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      8 years ago, # ^ |
        Vote: I like it +155 Vote: I do not like it

      Awesome problem!

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

      I'm sorry, our best naive solution worked in 14s. I can't find any counter-test for jqdai0815's solution :-(

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        8 years ago, # ^ |
          Vote: I like it +57 Vote: I do not like it

        He just compressed dfs-es in one in order to jump less over the memory. Actually, that's the usual problem with solutions like O(n*log^10).

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

      Yeah, more awesome because so far it is the only accepted solution.

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8 years ago, # |
  Vote: I like it -6 Vote: I do not like it

harder than usual but problems are so nice!

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

We need Nicolas Cage from National Treasure to figure out the problems' statements :( . I read the statements many times to understand the problems :(

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8 years ago, # |
  Vote: I like it +109 Vote: I do not like it

The Russian statements look much like a result of some automatic translation: the order of words is as in English, and sometimes the meaning is messed up, too. Still possible to understand, but English version looks more readable to me. Looked way better when Codeforces had staff dedicated to translating the statements, like Delinur.

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    8 years ago, # ^ |
      Vote: I like it -90 Vote: I do not like it

    There should be no Russian at all. Authors should just focus on English. Quite often there was a reverse situation when native Russian speakers didn't care enough for good english statements.

    The whole codeforces.ru should be translated into english and removed.

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

The problems are too hard to understand.Could you make the problems become shorter,it is unfair to poor English men...like me

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

can't figure out why my solution 25749847 for B is failing. could anyone please have a look.

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    8 years ago, # ^ |
      Vote: I like it +6 Vote: I do not like it

    you are using break without reading the whole line..

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8 years ago, # |
  Vote: I like it +36 Vote: I do not like it

Are all round prepared by PrinceOfPersia have a hard Div 1 A? Or am I too weak?

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

    His last contest has pretty easy Div1-A. All other problem though...

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

Test Case 24?

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

    This question is so weird.

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

    Try this test case : 1000 1 2 -4 -4

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

      Thanks

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

      Wait, what? It is said that noone can join the group more than once.

      Oh god. I got it. I should have read the text better.

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

        no it isn't

        Ricks and Mortys have registered online in these groups. So, a person can have joined a group more than once (developer of this website hadn't considered this possibility).

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

          Thanks. I've read "can't"

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

Fastest System Test ever :'D

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

WHat is the proof Of DIV2 A ? I cant guess the impossible (-1) case . When it will be impossible ? And whats the proof ?

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

    if both guys from same planet are in the same group then that group is not the required group as both from the same planet can't be traitor at the same time

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

    For example:

    a = 2, b = 1, c = 4, d = 4.

    We are adding even number to odd number, so it will be odd number, but c and d are even, their sum will be even to.

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

    b + n * a = d + m * c
    therfore :- a * n + (-c) * m = (d — b)
    this can be solved using extended gcd. if (d — b) % gcd(a, c) != 0 then answer is -1.

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

I tried Bezout's Identity for Div2A . But it failed....can anyone correct me.

Also, I can't think of when would it be -1.

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

That moment when you get div. 2 problem A wrong in system test

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8 years ago, # |
  Vote: I like it +59 Vote: I do not like it

pretty balanced

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8 years ago, # |
  Vote: I like it +84 Vote: I do not like it

It isn't a good idea to make Div1 A so difficult.
795 users registered for this Div1 round but only 343 made at least one submission.

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

    Please say this to topcoder admins too! :P

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

This time lots of Hacks & System failures! :p

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

Please Can someone tell why i got WA in Prob B ?

http://codeforces.me/contest/787/submission/25753050

///

I got accepted.

same number can come...

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

So easy div2 B problem, but so difficult-to-understand problem statement.

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8 years ago, # |
  Vote: I like it +7 Vote: I do not like it

Puzzle: Name of all problems are names of Eminem songs, except for Div.1 E. Eminem has no song named ALT, so what is the story behind ALT!?

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

Could you guys help me with why I got Div2B wrong?

http://codeforces.me/contest/787/submission/25748568

I think I misunderstood something.

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8 years ago, # |
  Vote: I like it +6 Vote: I do not like it

b should be 1500 and c 1000

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8 years ago, # |
← Rev. 2   Vote: I like it -64 Vote: I do not like it

PrinceOfPersia EVEN A BLUE CODER OR CYAN CODER CAN MAKE CONTEST WITH UNIFORMITY IN PROBLEMS LEVELS THAN THIS CONTEST.FOR EXAMPLE,TAKE SOME PREVIOUS CONTESTS

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

Beautiful arts) I was enjoying this contest)

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

My code of div2B WA vs AC after contest
My Code failed on #59. Can someone explain me how this passed 58 test cases ! !!
My best experience in CF.... I will remember it :'(

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8 years ago, # |
  Vote: I like it -10 Vote: I do not like it

Is it rated?

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

please i want to know something: i made this submission during the contest: http://codeforces.me/contest/787/submission/25739022 and then i made another submission in the same problem because there was something i was not sure of, the other submission was hacked, and the first submission above was counted hacked also as you see in the submission link

after the contest i submitted the above submission again exactly and it is accepeted: http://codeforces.me/contest/787/submission/25754392

is this normal ?

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

    I'd guess a yes

    It is probably because only the last one that passed all the pretests count for the contest, so your correct submission during the contests technically did not count

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

why.... http://codeforces.me/contest/787/submission/25746564

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

A positive rating change means absolutely nothing when u know u have not done well at all in the contest. :(

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8 years ago, # |
  Vote: I like it -23 Vote: I do not like it

Hello, I think I found a mistake in system tests in task B. Time limit is 2s and I've found the test in which solution has been executing for 2.8s but system test said that it is valid.

http://codeforces.me/contest/787/submission/25744252 the test is :

10000 1

10000 1 1 1 1 1 1 1 1... 1

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

    2.8s on your machine maybe, probably without -O2

    Custom Invocation 46ms

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

I was able to lock my solution after being hacked. HOW?

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

wasn't the character next to Rick in div1 D (Rap God) Pearl from Steven Universe?

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

I've got a mysterious submission issue;

Here's my code:

http://codeforces.me/contest/786/submission/29148189

It meets a RTE with a exit code which usually means array/vector visit out of range.

But my vs2017 report nothing and runs well, and I had never disable runtime warnings.

So I submited it in MS C++.

The first time it runs and I've got a minor mistake.

before correction

after I corrected it with only one line, it cannot even compile.

after correction

And the bs reason

Can't compile file:
program.cpp
program.cpp(58) : error C2143: syntax error : missing ',' before ':'
program.cpp(58) : error C2530: 'i' : references must be initialized
program.cpp(58) : error C3531: 'i': a symbol whose type contains 'auto' must have an initializer
program.cpp(59) : error C2143: syntax error : missing ';' before '{'
program.cpp(61) : error C2228: left of '.first' must have class/struct/union
        type is 'int'
program.cpp(61) : error C2228: left of '.second' must have class/struct/union
        type is 'int'
program.cpp(62) : error C2228: left of '.first' must have class/struct/union
        type is 'int'
program.cpp(62) : error C2228: left of '.second' must have class/struct/union
        type is 'int'
program.cpp(113) : error C2143: syntax error : missing ',' before ':'
program.cpp(113) : error C2530: 'i' : references must be initialized
program.cpp(113) : error C3531: 'i': a symbol whose type contains 'auto' must have an initializer
program.cpp(114) : error C2143: syntax error : missing ';' before '{'
program.cpp(115) : error C2228: left of '.first' must have class/struct/union
        type is 'int'
program.cpp(115) : error C2228: left of '.second' must have class/struct/union
        type is 'int'
program.cpp(194) : error C2143: syntax error : missing ',' before ':'
program.cpp(194) : error C3531: 'j': a symbol whose type contains 'auto' must have an initializer
program.cpp(195) : error C2143: syntax error : missing ';' before '{'
program.cpp(196) : error C2143: syntax error : missing ',' before ':'
program.cpp(196) : error C3531: 'k': a symbol whose type contains 'auto' must have an initializer
program.cpp(197) : error C2143: syntax error : missing ';' before '{'

I got really frustrated. Can someone help? What's going on?

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