e-maxx's blog

Codeforces Beta Round #30 (Codeforces format)
By e-maxx, 14 years ago, translation, In English

Today's contest was prepared by Saratov SU 2 team (Maxim Ivanov, Artem Rakhov, Nickolay Kuznetsov).


You will be asked to solve five easy and not so easy problems for some King, whom you hardly heard anything before. The king hopes that the problems won't turn out very difficult to you, and he will have a wide choice among different solutions to each of the problems.


UPD. The contest has finished, thanks to all of you.

The Results table.

Greeting to rng_58 for his win in today's round!


Problem tutorials: A, B, C, D, E.




Thanks to Mike Mirzayanov and Dmitry Matov who helped to prepare this round too.


Problem statements can be downloaded as a single PDF-file:


P.S. Don't forget to look through Codeforces Format contest rules, if you participate for the first time!

  • Vote: I like it
  • +50
  • Vote: I do not like it

Comments Comments (38)
| Write comment?
14 years ago, # |
  Vote: I like it +28 Vote: I do not like it
Your username reminds me about GNU Emacs!
→ Reply
14 years ago, # |
  Vote: I like it +3 Vote: I do not like it
→ Reply
  • 14 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    pretest #2 for problem A ? couldn't figure out where I'm doing it wrong.

    Sorry for the white message, don't know what happened.
    → Reply
    • 14 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it

      it's the same as sample test #2.

      check that you use the same compiler and the same settings on your computer as in system.

      → Reply
      • 14 years ago, # ^ |
          Vote: I like it 0 Vote: I do not like it
        Same error with me...
        I think that pretest #2 was different from test #2
        → Reply
        • 14 years ago, # ^ |
            Vote: I like it 0 Vote: I do not like it
          → Reply
        • 14 years ago, # ^ |
            Vote: I like it 0 Vote: I do not like it

          No, it was absolutely the same.

          I didn't look at your solution, but some people had problems with floating-point numbers: they work differently in different compilers.

          → Reply
          • 14 years ago, # ^ |
              Vote: I like it 0 Vote: I do not like it
            Weird because I use G++ 4 and here is all right for all samples.
            BTW, thank you reply.
            → Reply
14 years ago, # |
  Vote: I like it 0 Vote: I do not like it
What was pretest 6 for problem A?
→ Reply
14 years ago, # |
  Vote: I like it 0 Vote: I do not like it
What was pretest 7 for problem B?
→ Reply
14 years ago, # |
  Vote: I like it 0 Vote: I do not like it
Whats 33 test case in B?
→ Reply
14 years ago, # |
  Vote: I like it 0 Vote: I do not like it
If you please, what's test 75 for problem B?
→ Reply
14 years ago, # |
  Vote: I like it +6 Vote: I do not like it
Small request. Is it possible to give english links (to standings, problems, editorial, etc.) on english codeforces? It will be just more comfortable :)
→ Reply
14 years ago, # |
  Vote: I like it +4 Vote: I do not like it
Sorry for speaking out my real feelings.......
Problem A, B & C are too easy, just with some boring tricks.
Problem D & E are too hard for most contestants.
So if you solve problem ABC fast and get a few hacks, you will get a pretty ranking.
That's not intersting...
→ Reply
  • 14 years ago, # ^ |
      Vote: I like it +4 Vote: I do not like it
    If you thought that you solved problems correctly and the last 2 tasks were too difficult, you could start hacking. Of course first 3 problems were easy, but it was good possibility to use hacks.
    → Reply
14 years ago, # |
  Vote: I like it +19 Vote: I do not like it
I think there should be a strict policy: either don't show the test cases at all (I mean, don't answer the questions in this thread as well), or make a centralized place for them once and for all. (For example, show a link to a failed test on the status page near the submission's verdict.) The way it's done now is the worst possible one: I don't want to see a 'discussion' consisting mostly of requests to reveal a test.
→ Reply
  • 14 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    UP!!  I agree with your opinion very much! Most people like to ask what the test is, then  debug, I don't think this is a good way to AC.
    → Reply
    • 14 years ago, # ^ |
        Vote: I like it +3 Vote: I do not like it
      How one gets his AC's is his own business, my point is that any variant would be better than what we have now.
      → Reply
14 years ago, # |
  Vote: I like it 0 Vote: I do not like it
I would like to know why I got Runtime error on pretest 1 when using ruby for problem B. I am pretty sure there is nothing wrong with my code. I can also post it if needed.
→ Reply
14 years ago, # |
  Vote: I like it 0 Vote: I do not like it
for Problem A, both of my following approach works fine...
1.
if b=0 then result(0), end

for i = -1000 to 1000
if process(i)=true then result(i), end

result(NO), end

2.
for i = 0 to 1000
if process(i)=true then result(i), end
if process(-i)=true then result(-i), end

result(NO), end

But following got wrong answer on pretest 6
for i = -1000 to 1000
if process(i)=true then result(i), end

result(NO), end

It seems, it is required to output 0 when b=0, though any other answer may also be correct. I'm not sure about that.

If I am wrong, please anybody explain.

Can anybody give me actual pretest 6 for problem A?

Sorry about my poor English and for re-posting.
→ Reply
  • 14 years ago, # ^ |
      Vote: I like it +3 Vote: I do not like it
    check overflow in process function
    PS 
    if process(i)=true 
    same as 
    if process(i)
    → Reply
    • 14 years ago, # ^ |
        Vote: I like it 0 Vote: I do not like it
      For all the approaches (accepted or wrong answer) process function is same. If overflow occurs for an approach, it should occur for all the others. Moreover process function is not recursive. So it cannot overflow.
      → Reply
14 years ago, # |
  Vote: I like it +1 Vote: I do not like it
My problem B's code was hacked during the contest and that was right, but when I resubmitted it after the contest it got Accepted!!.
It seems the testcases for problem B are not complete.
→ Reply
  • 14 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    This is the same case as of Beta Round #29 problem A!!!
    → Reply
14 years ago, # |
  Vote: I like it 0 Vote: I do not like it
it will be better if we can see the cases for what we didnt pass system test 
→ Reply
  • 14 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    I agree. It can be shown after the contest.
    → Reply
14 years ago, # |
  Vote: I like it 0 Vote: I do not like it
Is there some problem on the Server? The Judgement is really slow...
→ Reply
14 years ago, # |
  Vote: I like it 0 Vote: I do not like it
What was the final test 10 of B?
→ Reply
14 years ago, # |
  Vote: I like it 0 Vote: I do not like it

Sorry, can the tutorial in English?

→ Reply
  • 14 years ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    It is in English, at least half of it :) Tutorial for C hasn't been translated into English yet, and there is no tutorial for B yet. Wait a bit, please :)
    → Reply
14 years ago, # |
  Vote: I like it 0 Vote: I do not like it

What happened to the judge?

→ Reply
14 years ago, # |
  Vote: I like it 0 Vote: I do not like it
what is the testcase 4 of problem E :(
→ Reply
  • 14 years ago, # ^ |
      Vote: I like it +1 Vote: I do not like it
    "y"
    → Reply
    • 14 years ago, # ^ |
      ← Rev. 2   Vote: I like it 0 Vote: I do not like it
      sorry, i wrong answer in testcase 14, not in testcase 4.
      → Reply
      • 14 years ago, # ^ |
          Vote: I like it +1 Vote: I do not like it

        It's a random test:

        "qmdmxlhwjldezdahqtixkbdtvuzjsgoirrwrqrbtulnhixpmghfjcbwgtcikpsgdfgvhxhrlqbmhlffr"

        one of the answers:

        3
        33 1
        34 3
        80 1

        → Reply
        • 14 years ago, # ^ |
            Vote: I like it 0 Vote: I do not like it
          thanks you very much! I got AC.
          And i really interested your site, although it is in Russian :)
          → Reply