Comments Comments (77)
Write comment?
 
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it
Are you going to introduce these rules in beta round 19 or make another unrated round for greater number of people?
→ Reply
  •  
    23 months ago, # ^ |
      Vote: I like it +3 Vote: I do not like it
    The second. It will be Codeforces Alpha Round #21 (Codeforces format)
    → Reply
    •  
      23 months ago, # ^ |
        Vote: I like it 0 Vote: I do not like it
      will Codeforces Alpha Round #21 be rated?
      → Reply
    •  
      23 months ago, # ^ |
        Vote: I like it +3 Vote: I do not like it
      one question, If one's solution is hacked(but not by us), can we still see the code but we are not given permission to hack or we can't see the code and there is no permission to hack?
      → Reply
      •  
        23 months ago, # ^ |
          Vote: I like it 0 Vote: I do not like it
        Probably you may not see someone's solution if it's already hacked.
        It'll be so until that someone submit a new solution (if the problem wasn't closed; if closed - NO WAI), that again passes pretests And tests, that used to hack this person's solution before.
        → Reply
 
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it
I think that these rules seem interesting, we should see in practice how they works :)
→ Reply
 
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it
I think it would be good if there were an additionally, say, 20 minutes of hacking after the first two hours have passed. No further submissions could be made during this time, only hacking. But then again, perhaps the two hours are enough. I can't wait to try this. :)
→ Reply
 
23 months ago, # |
  Vote: I like it +16 Vote: I do not like it
This contest style looks pretty cool. I don't think extra time is necessary for hacking after the contest. In Division I contests for me at least, I usually do 3 problems or so, and then don't know how to do the others :P So I'll have time to hack :D
→ Reply
 
23 months ago, # |
  Vote: I like it -3 Vote: I do not like it
I don't think hacking is an effective way to get scores with this rule. (It decreases the time to solve problems, and we can't resubmit if we try to hack.) I think it will work fine if there is no penalty for unsuccessful hacking.
→ Reply
  •  
    23 months ago, # ^ |
      Vote: I like it +1 Vote: I do not like it
    But if there is no penalty for unsuccessful hacking, then people might start making hacks recklessly without analyzing the solutions.
    → Reply
    •  
      21 month(s) ago, # ^ |
        Vote: I like it +4 Vote: I do not like it
      Would that really be a bad thing?

       If BF/load are issues just add an X seconds delay between hacking attempts.

      I don't really think it would be useful to try "hacking" at all. In TC challenges were already too much of an unusable gimmick for most div1 coders.  But if besides of the risk of losing points, you also add that you cannot resubmit any more and that you have to use time during coding phase it is too much.
      → Reply
      •  
        21 month(s) ago, # ^ |
          Vote: I like it -1 Vote: I do not like it
        I really prefer it in the normal ICPC format than adding the hack stuff. As you said, challenging in TopCoder is useless for me in div1.
        → Reply
  •  
    23 months ago, # ^ |
      Vote: I like it +1 Vote: I do not like it
    Sometimes too few time left and you know that it's not enough for solving one more problem. It'f perfect moment to start hacking).
    One more argument for making penalty for unsuccessful hacking - it should stop hacking flood and brute force hacking :-D
    → Reply
 
23 months ago, # |
  Vote: I like it +1 Vote: I do not like it
Why revealing that a solution has been hacked at all?

Just give the outcome result to the hacker and add or subtract the points, but don't reveal anything else.

That has been proposed in TopCoder forums long ago but I can't find it anymore. 

I think that this it is even better opportunity to use these rules considering that hacking and coding phases are not disjoint here.

I find it somewhat unfair to you get the info that your solution is flawed and you get to resubmit it, but I don't get it just because someone hacked yours. This rule would prevent this.

Also, you can't submit something that doesn't work at all so that the whole room would feast on it. The submission must pass this basic test set so I wouldn't mind if two people find the same bug and both get points for it.

Please consider the idea. I really think it would fit here.

Luka
→ Reply
  •  
    23 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    With current rules there is an important trade-off: you either try to hack solutions (but then the points for problems that you haven't submitted yet are decreasing) or solve other problems (but then you risk missing a lot of points for hacking). With what you suggest the second problem becomes much less critical, if not disappears at all.
    → Reply
    •  
      23 months ago, # ^ |
        Vote: I like it 0 Vote: I do not like it
      Sure.

      I just think that for me as a contestant it would be much better if I didn't have to depend on other peoples strategies and luck. I can devote as much time as I like to coding and spend the rest hacking.

      Everybody choose their own strategies but it doesn't effect others. This way luck factor is greatly reduced to the room assignment. The order I check others solution doesn't matter and the time I start checking others solution doesn't matter. Only my hacking skill and the strategy I choose matters.

      While I understand your point, I disagree that having this trade-off around is valuable. It might be fun in the beginning, but I think it would be chaotic - the rush to be the first to hack would be annoying and in the end I think that luck would play a significant role to the success of chosen strategy. 

      Keeping track of the scoreboard all the time would be pretty distracting for problem solving that is still (I think) the most important part of algorithmic contests.

      Well, maybe I'm wrong :)
      → Reply
      •  
        23 months ago, # ^ |
          Vote: I like it 0 Vote: I do not like it
        Have you participated in Alpha Round #20? It was very fun! :)
        IMHO, with your system the whole idea of combining the coding and the hacking phases together almost doesn't make sense. I agree that the importance of hacking is now emphasized, but well, that's the feature of the format. By the way, in alpha round #20 ivan.popelyshev started to hack solutions only after he submitted all 3 problems himself, and still made it to the 1st place.

        As for the tracking of the scoreboard — I'm sure there will be improvements of the interface that will make this easier.
        → Reply
  •  
    4 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    I like the idea that contestant with hacked solution have no info about it and more than one room contestants could gain points for hacking such solution.
    → Reply
 
23 months ago, # |
  Vote: I like it +1 Vote: I do not like it
What happens if I am 'confident' that I can not solve a problem in the given time. Can I lock that problem without submitting a solution and hack others solution for that problem?

I liked the idea of silent and multiple hacking by Kalinov. It makes sense.
→ Reply
  •  
    23 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    No, you can't lock a problem without submiting a solution. You can lock the problem and hack other solutions only if you solution passed all pretests.
    → Reply
 
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it
I have a few questions about the new format:

1. The way I understand it, we cannot hack at problems we haven't submitted and locked ourselves. But we might have formulated usable test cases, even if we failed to submit. Would it be possible to lock a problem we haven't submitted - in effect we forfeit our chance to submit the problem any more in the contest - and then challenge?

2. In TopCoder, the text of solution code is unobtainable by copy-paste or any other way. This is essential to prevent automated challenges. Is there a similar restriction in the new format?

On the whole, this new format looks promising. Looking forward to the first rated match.
→ Reply
  •  
    23 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    2. In TopCoder, the text of solution code is unobtainable by copy-paste or any other way. This is essential to prevent automated challenges. Is there a similar restriction in the new format?
    No, you can't copy-paste other's solution.
    → Reply
    •  
      23 months ago, # ^ |
        Vote: I like it 0 Vote: I do not like it
      You can copy-paste other solution. It was proved by me.
      → Reply
      •  
        23 months ago, # ^ |
          Vote: I like it 0 Vote: I do not like it
        Here by Russian http://codeforces.ru/blog/entry/468#comment-6868
        → Reply
        •  
          23 months ago, # ^ |
            Vote: I like it 0 Vote: I do not like it
          It's a bug, the question was about rules.
          → Reply
          •  
            23 months ago, # ^ |
              Vote: I like it 0 Vote: I do not like it
            It's look like that authors tried to protect code by using flash.
            → Reply
 
23 months ago, # |
  Vote: I like it 0 Vote: I do not like it
Few more questions about the new format:

1- Rules talk about obfuscation, but is there any restriction similar to TopCoder's unused code rule? I have many defines for input reading in my Codeforces source template. They aren't meant to make it hard to read the code, but most of them are not used in a single problem, so there is a lot of unused code. For the CodeJam I added a comment at the beginning explaining the source file structure and where to find the problem solution related code.

An example of the defines are
#define InInt(N) int N; scanf("%d", &N)
#define InVectorInt(X, N) vector<int> X(N); for ( int i = 0; i < N; ++i ) scanf("%d", &X[i])

The input section of the main method may look something like
...
InInt1(N);
InVectorInt(points, N);
...

2- It has been stated that you can't hack without successfully passing the pretests, but how about making a solution that one knows passes many cases but not all. Submitting it, and adding small hacks to it until it passes the pretest and locking it. Then I start to hack others, what happens if my code gets hacked? Can I still hack others? Is it considered fair to have such an approach to be able to get hack points even if I can't solve the real problem? Rules says that worst cases aren't tested by the pretests, so maybe I can make a brute force, or maybe an O(N^3) solution when N <= 500, knowing that worst case won't pass but maybe pretests are small enough. If this isn't considered ethical enough (rule #14) it would be hard to determine if it isn't an honest mistake, so maybe allowing to lock a problem without passing pretests is the only way to really disallow this.
→ Reply
  •  
    23 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    what happens if my code gets hacked? Can I still hack others?
    You can still hack others
    → Reply
 
23 months ago, # |
  Vote: I like it +3 Vote: I do not like it
There seems to be a week point in the in-time-of-contest hacking. If someone with a fake ID (or lets say two friends) are in the same room, he may submit for N times (for an arbitrarily large amount of N) using his fake ID, and hack his solution with th original ID. This way, he gets 100*N points for free (which worths a lot for an arbitrarily large amount of N) :D
P.S. I can see that this way you will be mention his cheating and will disqualify him, but it's just a matter of canceling the potential of cheating as much as you can. Also, note that you won't even think of cheating if the process is done for a small value of N.

Solution: Don't let someone hack another ones solution for more than once (or twice)
→ Reply
  •  
    20 months ago, # ^ |
      Vote: I like it -3 Vote: I do not like it
    Sorry for writing in Persian:
    بابا اینها عقلشون به این جاها نمی رسه
    فقط ما ایرانیها این چیزها به ذهنمون می رسه
    → Reply
  •  
    20 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    راضیم ازت، عالی بود!
    → Reply
 
21 month(s) ago, # |
  Vote: I like it 0 Vote: I do not like it
round #26 is rated or not??
→ Reply
  •  
    21 month(s) ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    Yes. round #26 is rated
    Sorry for my bad English
    → Reply
 
21 month(s) ago, # |
  Vote: I like it 0 Vote: I do not like it
I think it will be great to creat a raiting table for each room, something like on TopCoder, very comfortable. And from this table to have possibility to open users source codes for each task and also problem's text.
hm?
→ Reply
 
20 months ago, # |
  Vote: I like it 0 Vote: I do not like it
Hey everyone I'm new to this website and I have a question about submitting my codes. I tried submitting a java type file and i kept getting an error. any tips on how one should go about submitting your code for a contest.
→ Reply
  •  
    20 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    What error?
    Here's a sample Java solution for problem A from beta round #1
    → Reply
  •  
    20 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    You can check other solutions. Some steps:
    1. Proceed to the "Contests" page. (link)
    2. Enter one of the previous contests. (example)
    3. Proceed to the "status" page (status)
    4. Find some accepted solutions in Java
    5. Look at the code clicking the solution ID link.

    P.S. It seems to be that you just print the answers for the sample tests. Instead you should read the input data from the standard input stream.
    → Reply
    •  
      20 months ago, # ^ |
        Vote: I like it 0 Vote: I do not like it
      Thanks. Reading in the data was my problem. Appreciate your help.
      → Reply
 
20 months ago, # |
  Vote: I like it 0 Vote: I do not like it
Is it no more possible for DIV1 contestants to take part in contest only for DIV2 and be out of competition?
→ Reply
  •  
    20 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    Not for Codeforces format rounds for now. But it will be in the future.
    → Reply
 
20 months ago, # |
  Vote: I like it +12 Vote: I do not like it
while I see the benefits to this approach, I never liked the whole hacking thing.  TopCoder does it and has been doing it for a long time, so fine, let it be.  I did like the original CodeForces judging way, such as used in the first 5 contests and onwards.  Having said that, I am not entirely opposed to the new way.  I haven't tried the new rules yet, so it will be interesting to see how it feels.
→ Reply
 
20 months ago, # |
  Vote: I like it +3 Vote: I do not like it
Can I do a request? Plz Plz don't forget the ICPC formet. Have some contests on that format also plz.
→ Reply
 
20 months ago, # |
  Vote: I like it 0 Vote: I do not like it
Can you resubmit your code after locking your code or your code be hacked by others?
→ Reply
  •  
    20 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    If you lock your code you can't resabmit it. In any other situation you can do it, but the score on this problem wiil be less, becose of time between submitions and 50-points penalty.
    → Reply
 
19 months ago, # |
  Vote: I like it +3 Vote: I do not like it

What about the following idea: after the finish of each contest, problemsetters upload all tests to all their problems as an archive (to some site). It's not difficult for authors to take an archive from the system ('Polygon') where the problems are created.

I don't know when the feature of viewing test data will be available on Codeforces, so I suppose this is the best solution. It's really not a good idea to ask tests in comments on the site, IMHO.

→ Reply
 
19 months ago, # |
  Vote: I like it 0 Vote: I do not like it
On the 32nd round I noticed div1 contestants couldn't hack others' solutions. Is it going to be like that in div2 only?
→ Reply
 
19 months ago, # |
  Vote: I like it 0 Vote: I do not like it
Will out of competition user's rating change after the contest??
→ Reply
 
19 months ago, # |
  Vote: I like it 0 Vote: I do not like it
I think codeforces can add a function that contestants can view others' codes after the contests in his/her room.
During the contest, I may not find a program's bug. When it failed system tests, I want to see it again ..
→ Reply
 
19 months ago, # |
  Vote: I like it +3 Vote: I do not like it
I was looking for these rules on the site without much luck - the link is provided in the email, can it be visible somewhere on the Home or Contest pages? I see now that the link can be found under 'Recent Actions' but, at least for me, it is not really a place I would go to when looking for the rules.
→ Reply
 
14 months ago, # |
  Vote: I like it 0 Vote: I do not like it
can u please allot div 2 members to seperate rooms and div 1 members to seperate rooms ?? like they do in topcoder ...
→ Reply
  •  
    14 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    In the case div 1 and div 2 are together - the div 2 contestants' wrong solutions will be hacked earlier and they'll get an opportunity to resubmit a correct solution.
    → Reply
 
12 months ago, # |
  Vote: I like it +7 Vote: I do not like it
@MikeMirzayanov: Any particular reason why successful hacks are not added to the global system tests?

I am asking because some hacks may expose bugs that the system tests may not cover.  In such a situation, a solution may get accepted because the author of the hack failed to check the solution or was in a different room.
→ Reply
 
12 months ago, # |
  Vote: I like it 0 Vote: I do not like it
Please fix "loose" to "lose". :)
→ Reply
 
11 months ago, # |
  Vote: I like it 0 Vote: I do not like it
Heyi.. how to register for contests? i am new to this site. and i didnt find any link which refers to "Registration for Contests".. i am little bit confused. am i eligible for contests or not? please give me an answer quick , so that i can register quick if i am eligible... 
→ Reply
  •  
    11 months ago, # ^ |
    ← Rev. 2   Vote: I like it +1 Vote: I do not like it

    registration will be available here after 7:00am (msk)
    → Reply
    •  
      11 months ago, # ^ |
        Vote: I like it 0 Vote: I do not like it
      whats the time in GMT format?
      → Reply
      •  
        11 months ago, # ^ |
          Vote: I like it +1 Vote: I do not like it
        Time of registration shows here (in last column).
        → Reply
      •  
        11 months ago, # ^ |
          Vote: I like it 0 Vote: I do not like it
        Sorry, I forgot about other timezones.
        As Dembel say, you can see, when registration start on contest page. Registration to next contest starts in 12 hours before contest
        → Reply
    •  
      11 months ago, # ^ |
        Vote: I like it +1 Vote: I do not like it
      7:00 am will be after about 9 hours :)
      → Reply
 
9 months ago, # |
  Vote: I like it 0 Vote: I do not like it
Hi, im new here.. I am just wondering .. what if i don't submit a prob ? Will that reduce my results? (Please don't mind if my English is not so good..)   ^_^
→ Reply
  •  
    9 months ago, # ^ |
      Vote: I like it 0 Vote: I do not like it
    Your rating changes if and only if you submit a solution. You may carelessly register and watch prob. statements (you can do it even logged out) without worrying about rating. :)
    → Reply
 
9 months ago, # |
← Rev. 2   Vote: I like it 0 Vote: I do not like it

I have noticed I cannot cancel my registration to a contest anymore. If I'm not mistaken, now the rules are that if you send a solution you will be rated.

UPD: Ok now I'm sure about it. It's a pity I cannot partecipate in this round... waiting for next week :)
→ Reply
 
»
4 months ago, # |
  Vote: I like it 0 Vote: I do not like it
How a contest point include to CodeForces rating point ??
→ Reply
  •  
    »
    »
    4 months ago, # ^ |
      Vote: I like it +12 Vote: I do not like it
    Only the rank is important. Points as numbers don't mean anything.

    Exact formula is not public.
    → Reply
 
»
4 months ago, # |
← Rev. 3   Vote: I like it -5 Vote: I do not like it
I have a suggestion. 
Maybe... we can get different scores after hacking different problems.
i.e. for problem X, if its max. score is S, we can get S * 10%  points after a successful hacking attempt, or lose S * 5% points after unsuccessful hacking attempt. 
Er, just a personal thought,^_^...
→ Reply
  •  
    »
    »
    4 months ago, # ^ |
      Vote: I like it +3 Vote: I do not like it
    It is not a good idea, I think. The difficulty of a problem is not relevant to the hacking difficulty. Sometimes it is easier to hack harder problem since there is a good chance for someone to have buggy implementation or wrong algorithm on it. On the other hand, sometimes tricky easy problem gives more opportunity for successful challenges.
    → Reply
 
»
4 months ago, # |
  Vote: I like it 0 Vote: I do not like it
Can I see the test case that was used to hack my solution after the contest?
→ Reply
  •  
    »
    »
    4 months ago, # ^ |
      Vote: I like it +3 Vote: I do not like it
    Yes. Goto "hacks" page in contest.
    → Reply
 
»
7 weeks ago, # |
  Vote: I like it 0 Vote: I do not like it

How can I see the whole input in Source view? i.e. Test #6

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

    Unfortunately, it’s impossible.

    → Reply