Sereja's blog

Codeforces Round #223
By Sereja, 10 years ago, translation, In English

Hello everyone!

Codeforces Round #223 will take place on Sunday, January 12th at 19:30 MSK. This is my tenth Codeforces round and I hope not the last.

I'd like to thank Gerald for helping me to prepare the round. Special thanks to Delinur for translation of all problem statements into English.

I strongly recommend you to read ALL the problems.

This is the first round this year. Incidentally, the first round last year for both divisions was also mine (by statistics +1/-1 is was the coolest of rounds that I gave). I hope that this time the problems will be even more interesting for you. Will it? Will find it out after the round :)

Gl & hf ! :)

Problem point values will be standart for both divisions.

  • Vote: I like it
  • +338
  • Vote: I do not like it

Comments Comments (55)
| Write comment?
»
10 years ago, # |
  Vote: I like it +10 Vote: I do not like it

Sereja, You are savior man, You keep creating good problems regularly :)

→ Reply
»
10 years ago, # |
  Vote: I like it +96 Vote: I do not like it

Yess! Another Sereja's Round!

→ Reply
»
10 years ago, # |
  Vote: I like it +21 Vote: I do not like it

First Contest of 2014 :) Wish everyone a happy and successful year.. And High rating too :)

→ Reply
»
10 years ago, # |
  Vote: I like it +13 Vote: I do not like it

Hope it a year, with success, more contests, and faster system test.

→ Reply
»
10 years ago, # |
  Vote: I like it +17 Vote: I do not like it

According to your first problem in 2014(Sereja and Graph in CodeChef), it is obvious that this contest will be very interesting! :)

→ Reply
  • »
    »
    10 years ago, # ^ |
      Vote: I like it +18 Vote: I do not like it

    Does "Sereja and Graph" interesting problem?)

    → Reply
    • »
      »
      »
      10 years ago, # ^ |
        Vote: I like it +7 Vote: I do not like it

      It was very interesting at least for me. :) It caused me reading some articles and papers and learning new things. :)

      → Reply
      • »
        »
        »
        »
        10 years ago, # ^ |
        ← Rev. 2   Vote: I like it 0 Vote: I do not like it

        could you please tell me something about it when the contest is end?I have no idea how to solve it and got lots of WA.

        → Reply
    • »
      »
      »
      10 years ago, # ^ |
        Vote: I like it +3 Vote: I do not like it

      It does :|

      → Reply
»
10 years ago, # |
← Rev. 2   Vote: I like it -41 Vote: I do not like it

Sereja u forgot to thank MikeMirzayanov for creating Codeforces. :)

→ Reply
»
10 years ago, # |
  Vote: I like it -21 Vote: I do not like it

Sereja's problems are actually cool( although I only met 2 of them on CodeChef ).I can't wait to see how many AC submissions will fail on "Sereja and graphs" at the end . May it be a great round!

→ Reply
  • »
    »
    10 years ago, # ^ |
      Vote: I like it +8 Vote: I do not like it

    Codechef doesn't work that way. there's no pretests, all tests are system tests. once u get AC, u have solved that problem for sure.

    → Reply
    • »
      »
      »
      10 years ago, # ^ |
        Vote: I like it +2 Vote: I do not like it

      actually, you are not 100% correct. sometimes they update data-set during contest. once i got AC in this problem on January 3, they updated dataset on 6th January. and my code failed, i had to solve that problem again.

      → Reply
      • »
        »
        »
        »
        10 years ago, # ^ |
          Vote: I like it +3 Vote: I do not like it

        But the scores for the 9 non-challenge problems don't change after the end of the contest. That's the point.

        → Reply
»
10 years ago, # |
  Vote: I like it 0 Vote: I do not like it

A Happy New Year to all, and good luck on the first contest of 2014!

→ Reply
»
10 years ago, # |
  Vote: I like it +21 Vote: I do not like it

It seems great! This is my first join in the contest of Codeforces Round, I hope I can get good marks~ :>

→ Reply
»
10 years ago, # |
  Vote: I like it 0 Vote: I do not like it

1st round of 2014, a little late start i think.

→ Reply
  • »
    »
    10 years ago, # ^ |
      Vote: I like it +15 Vote: I do not like it

    Maybe 12th day it's pretty late, but note that there were 3 contests in last week of last year!

    → Reply
»
10 years ago, # |
  Vote: I like it -17 Vote: I do not like it

Good lucky to everyone!~~

→ Reply
»
10 years ago, # |
  Vote: I like it -13 Vote: I do not like it

Really nice New Year's first contest!Good luck to everyone!

→ Reply
»
10 years ago, # |
  Vote: I like it +85 Vote: I do not like it

In reply to this: http://codeforces.com/blog/entry/10138#comment-155733 Keep in mind that this will be a historic round, because today for the first time I'll become a yellowcoder from a redcoder :P. But I will try to keep this color :D.

→ Reply
  • »
    »
    10 years ago, # ^ |
      Vote: I like it +32 Vote: I do not like it

    → Reply
  • »
    »
    10 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    seeing ur previous post, i was like "oh my! what confidence!"

    now i am like "not sure if very over-confident, or very under-confident" :D

    → Reply
  • »
    »
    10 years ago, # ^ |
      Vote: I like it -9 Vote: I do not like it

    No,I am kind of saint and I am praying for you that your rating increases today :p

    → Reply
  • »
    »
    10 years ago, # ^ |
      Vote: I like it +24 Vote: I do not like it

    and he didn't make it... top21 and still red

    → Reply
  • »
    »
    10 years ago, # ^ |
      Vote: I like it +9 Vote: I do not like it

    Yesss! 21st place! It looks like my rating will increase even more :D

    → Reply
    • »
      »
      »
      10 years ago, # ^ |
        Vote: I like it +8 Vote: I do not like it

      Impressive work.I've watched you done that twice. Congratulations!

      → Reply
»
10 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Pretty tight pretests. It seems there will be comparatively less hacking this time.

→ Reply
»
10 years ago, # |
← Rev. 4   Vote: I like it +7 Vote: I do not like it

nice contest! thank you Sereja

→ Reply
»
10 years ago, # |
  Vote: I like it 0 Vote: I do not like it

only 10 successful hacks, of which 7 were on the comparatively difficult problem E.

Sereja, from next time plz try to make hacking more possible, as it is also an important part of contests.

→ Reply
  • »
    »
    10 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    From where can we see all the hacking attempts made in a contest?

    → Reply
    • »
      »
      »
      10 years ago, # ^ |
      ← Rev. 2   Vote: I like it +6 Vote: I do not like it

      u can see all successful hacking attempts in the Status tab, after changing verdict option under the filter to Hacked.

      if u want unsuccessful ones also, u can see them in the Hacks tab. but this usually takes a few hours after the round ends to become accessible to all users.

      → Reply
»
10 years ago, # |
  Vote: I like it 0 Vote: I do not like it

A contest where faulty point distribution can break one's day, C was solved by 3 times more people than B. Interesting set though.

→ Reply
  • »
    »
    10 years ago, # ^ |
      Vote: I like it +18 Vote: I do not like it

    Maybe C was a well known problem for top coders..

    → Reply
»
10 years ago, # |
← Rev. 2   Vote: I like it -9 Vote: I do not like it

Forgot to delete cerr... Got AC in almost the same code in problem C. I'm going to lose a lot of ratings...

→ Reply
»
10 years ago, # |
  Vote: I like it +38 Vote: I do not like it

superb speed of system testing today! i think MikeMirzayanov's New Year resolution was to install better testing computers! :D

→ Reply
»
10 years ago, # |
  Vote: I like it 0 Vote: I do not like it

NlogN solution for C. Time limit in test case 13 ... , i lost lots of rating points cause of my slow nlogn solution ... pfffff

→ Reply
»
10 years ago, # |
  Vote: I like it 0 Vote: I do not like it

What does this mean? wrong answer Unexpected EOF in the participants output

→ Reply
»
10 years ago, # |
  Vote: I like it +11 Vote: I do not like it

Why was E E? OwO

btw very fast system test :)

→ Reply
»
10 years ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

3 unsuccessful hacks :(

how this code passed test 14 for div2B?

→ Reply
  • »
    »
    10 years ago, # ^ |
      Vote: I like it +7 Vote: I do not like it

    Accessing out-of-bounds arrays in C++ is "undefined behavior", which means anything can happen: the computer might explode, it might corrupt memory, or, in this case, it can appear to work properly. :)

    → Reply
    • »
      »
      »
      10 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      my 3 hacking attempts is about this.

      I remember that I got RE in one of the past contests just for 1 more index of array.

      I was unlucky at the first contest in new year :(. what will be happen for me??

      → Reply
  • »
    »
    10 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it

    i think that the algorithm is correct, very strange but correct

    → Reply
    • »
      »
      »
      10 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      did you look at array size of b? it should be at least 10000, see test 14

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

Thanks a lot Sereja for another awesome round! :D

→ Reply
»
10 years ago, # |
  Vote: I like it 0 Vote: I do not like it

I have a problem. I cant'n see the solutions of other participants, neither test cases or hack somebody solution. Because the solution of someone else appears not in other web page, else in the same page, but this not work for me. Mi web browser is Firefox. Even for write this comment I had to use Internet Explorer. What I need to configure in Firefox for that works?

→ Reply
  • »
    »
    10 years ago, # ^ |
      Vote: I like it -8 Vote: I do not like it

    I think you have to install adobe flash player for firefox !

    → Reply
    • »
      »
      »
      10 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      Thanks, but I reset Firefox to it original configuration, and alls works. It seems that some features of firefox like some themes or add-ons were causing troubles.

      → Reply
»
10 years ago, # |
  Vote: I like it 0 Vote: I do not like it

So easy!

→ Reply