By MikeMirzayanov, 8 years ago, translation, In English,
This is the list of frequently asked questions concerning Codeforces work and answers to them.
  1. What is Codeforces? What kind of a site/resource is it?
  2. What should I do to participate in contests? Is preliminary registration required?
  3. What are the rules of the contests?
  4. What languages can I use to solve problems here? Are there any problem solving examples?
  5. I would like to organize a Codeforces round with my problems. What should I do to achieve that? Are the authors entitled to get any reward?
  6. What other rules are on Codeforces?
  7. Which technical details are useful to know about the Codeforces' testing system?
  8. What are the rating and the divisions?
  9. What is contribution?
  10. What blog posts are useful to take a look at?
  11. I've noticed that the site contains the solutions of all the contestants and the previous contests' tests. How is it allowed to use them?

Questions and answers:

  1. What is Codeforces? What kind of a site/resource is it?
    Codeforces is a project joining people interested in and taking part in programming contests. On one hand, Codeforces is a social network dedicated to programming and programming contests. On the other hand, it is a platform where contests are held regularly, the participant's skills are reflected by their rating and the former contests can be used to prepare. Codeforces constantly develops and we plan to improve the platform to give the participants the opportunity to organize their own contests, filling the project with learning content, developing Codeforces as a training and learning platform.
  2. What should I do to participate in contests? Is preliminary registration required?
    Contests are regularly held on Codeforces. Participating in them is free and open to everybody. Every month we organize approximately six contests. To participate, you have to be registered on the site (if you have an OpenID or a Gmail account, then you won't even have to memorize the password) and register for the oncoming contest. Make sure that you are present in the list of the users, registered for the contest, before the registration ends. Usually, if you can't take part in the contest officially (e.g. if it's the contest for the second division and you are in the first one), then you can register for the contest to participate out of competition.
  3. What are the rules of the contests?
    They are usually held according to the original Codeforces rules. If it is specially stated, then the International Collegiate Programming Contest rules ACM-ICPC or some other modifications can be used. In brief, on the contests held by Codeforces rules you write solutions to the problems that are tested during the contest on a very small number of tests. Those who have passed that set of solution tests, their authors can block (refuse to resend the solutions of this task in future even if they find a mistake). Such authors receive the opportunity to look through the sources of other contestants, look for mistakes there and suggest the tests on which these solutions do not work. Thus, you can hack somebody else's solution and earn points through it.
    After the contest all the solutions that have passed the pretests and haven't been hacked are tested on the final set of tests. The value of a task decreases during the contest (the faster you solve the problem, the more points you receive), unsuccessful hacks take off the points and the successful ones add them. Please take a look at the detailed version of the rules before participating in the contest.
  4. What languages can I use to solve problems here? Are there any problem solving examples?
  5. I would like to organize a Codeforces round with my problems. What should I do to achieve that? Are the authors entitled to get any reward?
    Do you want to organize a round? That's great! We are very pleased to hear that. The project's problem coordinator Gerald Agapov (aka Gerald) will be glad to help you prepare the tasks. You can contact Gerald by sending to him a personal message. We have great technological base to prepare the problems and the experience of organizing contests will be enjoyable to you and will also prove useful.
  6. What other rules are on Codeforces?
    We don't have a clear Great Codeforces Code of Conduct. However, of course, here you should behave in accordance with traditional rules of behavior in public places and theme groups. The following rules are, of course, necessary to follow:
    • Don't create more than one account, if you have forgotten the password, use the password reminding system.
    • Do not use harsh, rude or misleading handle.
    • Do not use anybody photo except yours. It is uncultured and could confuse Codeforces users.
    • Don't be rude, don't insult other participants and administration, try to be polite and pleasant to communicate with.
    • When you take part in individual contests, don't talk about the problems with other contestants, don't use somebody else's code or insert it into your solutions. If the contest is a team one, discuss the tasks only with the teammates.
    • Don't try to destabilize the site's and the checking system's work. Your programs should only interact with the console (for the problems with the standard input and output) or the input and output data files.
    • Don't publish or spread your solutions and solution ideas during the contest.
  7. Which technical details are useful to know about the Codeforces' testing system?
    The Codeforces system resembles classical Online Judges. The solutions are tested on the tests prepared beforehand (or the hacks suggested by other participants). As a result, you receive verdicts, the meaning of which is clear from the title. It should be specially noted that Codeforces does not have the "Presentation Error" verdict, this situation is regarded as "Wrong Answer". All the suspicious verdicts (testing error etc.) are not considered while evaluating the results. That is also true for the solutions that had fallen on test 1 (in the problems containing more than one test).
  8. What are the rating and the divisions?
    When the contesters take part in Codeforces contest, they raise or lower their rating that reflects their ability to solve the tasks. The rating is a modification of Elo rating, several details can be read in a fuller form. According to the rating, the contestants are split into two divisions: the second one (the weaker one, amateurs) and the first one (the stronger one, pros). The contestants who don't take part in contests and those whose rating is below 1900 belong to the second division. The 1900+ rating means that you're part of the first division. Usually two types of contests are held on Codeforces: for the second division contestants (the first division contestants can take part there out of competition) and for both divisions. The first contest type contains simpler and learning-oriented tasks.
  9. What is contribution?
    The votes for the posts and comments of a user change his/her contribution. The contribution is intended to show the usefulness of the community user. The contribution counting system is imperfect; in future the rules for its calculation will be changed.
  10. What blog posts are useful to take a look at?
  11. I've noticed that the site contains the solutions of all the contestants and the previous contests' tests. How is it allowed to use them?
    In fact, we publish materials from the past contests and they can be used, for example, for individual lessons. Using the materials on other Online Judges, public contests, etc. is prohibited. Be sure to read the license before using the materials.
    In order to view someone else's solution, just click on his id on the page "Status". From the page with the list of tasks you can go to the list of correct decisions for the given task. At the bottom of the "Status" pages (and others with the lists of decisions) there is an option of sorting the solutions on different criteria.
 
 
 
 
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8 years ago, # |
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@Mr.Mirzayanov:
You just forgot to translate 

Помощь

8 years ago, # |
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Hey how to register for the upcoming beta round #74 for div1
8 years ago, # |
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How to get into the country ranklist? There is no place in the settings to set my country.
8 years ago, # |
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Why is registration required?
I would like to register about 2-3 weeks ago, and I clicked on the register button, but I wasn't logged in, so Login window appeared and I logged in and after that I forgot to register, I thought I registered..Few hours later I started to solving the problems and after the first solved problem I realized I didn't register.. I know it's my problem, and my mistake.. So I just would like to know, any reason why registration is required? (example participate limit )
  • 8 years ago, # ^ |
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    It's required for dividing participants into rooms.
  • 8 years ago, # ^ |
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    Its also required for calculation of ratings.Codeforces uses Elo System of ratings.When you register u are given a predicted ranking in the contest based on ur current rating.For more details on the ratings you can go here(http://codeforces.com/blog/entry/102).
7 years ago, # |
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i get "wrong answer on pretest 1" or "idleness limit exceeded" whats d problem?
7 years ago, # |
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How can I find all the editorials? Search box gave 'no result' :(
7 years ago, # |
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What results in Denial of judgement?

  • 7 years ago, # ^ |
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    It's usually just some random server error. If you wait and then resubmit, it should judge correctly.

7 years ago, # |
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How do you ask for clarification about statement ambiguities during contests? Or is it impossible to do that?

Are there rules for pictures? The part in the profile editor says that your face must be clearly visible, but there are plenty of users with pictures that do not contain them.

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7 years ago, # |
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What is the best way to find an editorial, say for e.g. if I am looking for editorial of Round #88, how can I find it quickly?

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7 years ago, # |
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Links in "list of frequently asked questions" in the beginning of the blog has to be updated — it's not working.

I tried this link http://codeforces.com/blog/entry/1336#q8 and nothing happened.

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7 years ago, # |
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Can you add a feature to see friend's friends, like facebook? That would be very nice.

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7 years ago, # |
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Why the flags of my solved problems disappear? How can I make it appear again?

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7 years ago, # |
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It might prove to be useful if some comparison tool(s) can be implemented -- something like https://www.otinn.com/topcoder/al/comparer.php or http://topcoder.manabase.com/graph.php, except in CodeForces setting, instead of TopCoder.

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    7 years ago, # ^ |
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    Interesting tools, but most difficult for me is to beat myself :-D

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7 years ago, # |
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I want to change my HANDLE. How can I do this? Thanks for help.

When I'm entering to Esc>Settings>Handle there is message : "The page is temporary blocked by administrator. We are doing it because of increased load. Do not panic, we will unblock the page soon. Thank you for your understanding."

and When it will unblock? Thanks for help :D

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    7 years ago, # ^ |
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    This opportunity was a present from admins in the first days of new year.

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7 years ago, # |
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hello Mr.Mirzayanov How can i delete my team ?

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7 years ago, # |
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I have two problems. The first is where to complain about the problems with the site in general? Since I could not find a forum or a place to file my complaints I am writing it here in the FAQs. I don't know whether this has been brought up before or not, but those tags in the problems virtually make this site unusable for practice purposes. Most often knowing what method to use to solve a problem is half the solution and it is clearly right there for everyone to see! Can we make them hidden by default please (it should be shown only after a 'user action' like clicking an 'expand' button)?

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    7 years ago, # ^ |
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    You can disable tags for unsolved problems on the settings page.

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    7 years ago, # ^ |
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    It is possible, you can adjust the settings in the user profile.

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6 years ago, # |
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Can I download the test data of some problems? How?

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6 years ago, # |
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how to delete a favourite submission from favourites?

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    6 years ago, # ^ |
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    How did you have added it to favs? Unfavourite it in the same way.
    Click 1365856 and remove a star.

    And don't post so huge screenshots next time. ;)

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6 years ago, # |
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How to download all of my submissions (or just Accepted)?

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6 years ago, # |
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How must be format of the solution ? how can i get inputs and put output in solution for example in C++ language? I could not found any help to the above questions

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    6 years ago, # ^ |
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    All your code must be in one .cpp file.

    It must read data from standart input (stdin).
    It must write data to standrat output (stdout).

    For example:


    #include <iostream> using namespace std; int main(){ int a, b; cin >> a >> b; cout << a * b << endl; }
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6 years ago, # |
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Is there any way to delete (particular) talk(s)?

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6 years ago, # |
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Hi, If I virtually participate in a contest after it was officially held, the final result will affect my rating ?

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6 years ago, # |
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Can you add go as an official language? http://golang.org

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6 years ago, # |
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I believe you forgot to add anchor tags in the questions(explanation section).

When I click on a question, it doesn't take me to the place where the question is answered. Anchor tag along with the id is missing. Kindly do so to make the post user friendly.

Thanks

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6 years ago, # |
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Is there any mailing ID for help. Headquarters e-mail ID???

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    6 years ago, # ^ |
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    send message to Headquarters (here)

    I do it and I think i get my answer

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6 years ago, # |
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Could I ask is there any way I can see the details of my marked friends?

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6 years ago, # |
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the numeric list is wrong. .... so uncomfortable.

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    6 years ago, # ^ |
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    Why downvoting? It really is.

    UPD: it's quite cool to see that GCD's comment was upvoted so lot (at least it became positive) after this comment but myself I was downvoted so much...

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6 years ago, # |
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is there a long term calender for codeforces .. like topcoder's one ?. or how to know the time for next rounds and other contests along the month or along the year ? :)

thanks in advance :)

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5 years ago, # |
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Can DIV 1 users who participate "out of competition" in only DIV 2 contests, hack others' solution?

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    5 years ago, # ^ |
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    Yes but only div1-ers

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    5 years ago, # ^ |
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    And are they rated for div1 users? Asking for a friend.

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      no. div 1 users can participate in div 2 contest but the contest is unrated for them.

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5 years ago, # |
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I've got a problem with the site: is it possible to check out my own past submissions for a particular problem?

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5 years ago, # |
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How can we see all the solutions of a problem submitted in a specific programming language ?

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Why is my code skipped? (problem D contest 211 div 2)

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    5 years ago, # ^ |
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    same problem here. can anybody explain what the 'skipped' verdict means. I can't find anything on it.

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5 years ago, # |
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I have a big question. How do I delete my account (or change my handle) ? I am really unhappy with the name I got. (I know I chose it but I'm sorry).

Anticipated thanks. Lawliet

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    5 years ago, # ^ |
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    I don't think it is possible to change your handle. But since you haven't participated in any contests yet, why not just create a new account? Your handle isn't that bad btw :P

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      5 years ago, # ^ |
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      I don't want to create a new account because I need a new e-mail, and if I create an e-mail just for codeforces, I will end up missing all of the e-mails I get.

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        5 years ago, # ^ |
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        Mail programs (gmail, as an ex.) can collect mails from other email addresses

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    5 years ago, # ^ |
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    You can change your handle near January the First. A week for this operations always is given at New Year.

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5 years ago, # |
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Hello,

Can someone please tell me when will I be able to change my handle? I really don't want to miss my chance.

Anticipated thanks, Lawliet

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    5 years ago, # ^ |
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    u can change it anytime till the 10th January 2014.

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      5 years ago, # ^ |
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      That means I just missed it, right? I was nowhere close to my computer in the mid time... :( Crying out loud.

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      5 years ago, # ^ |
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      Isn't there something I can do now? I don't want to wait another year... sadface

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        5 years ago, # ^ |
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        Please, just stop moaning and start to solve problems.

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          5 years ago, # ^ |
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          I hate this situation. Sorry for causing trouble. It's just.... I just feel sad. I wanted my handle to be the name people know, but whatever. If I can't get my handle to be "Marron" this week I'll just make a new account. Thank you for all your assistance, and I say sorry again for causing trouble.

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5 years ago, # |
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how to add friends, so that we can see their rating??

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5 years ago, # |
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Hello How to organizers of the mail or memmage?

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    5 years ago, # ^ |
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    I'm sorry for my poor English.I mean how to send mail to the codeforces Official website organizer.

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5 years ago, # |
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can someone help me on, how to download problem statements from the site??

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    5 years ago, # ^ |
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    If there are not file of problem statements in contest, you can copypast them or take a screenshot

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5 years ago, # |
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The shortcuts to the questions are not working.

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5 years ago, # |
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I want to deactivate my account. How can I do that?

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5 years ago, # |
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I don't need this ID any more. Will anyone delete it?

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5 years ago, # |
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how to change my register email address??

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5 years ago, # |
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Right now I log in with my Gmail account. If I want to change it to have a username and password to log in, how can I do it?

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5 years ago, # |
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Could I delete my account ?

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    4 years ago, # ^ |
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    i want to delete my account too.. there must be a way .. it seems impossible!!!

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5 years ago, # |
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HIiii....

I am using codeblock to run c++ program...

My program gives correct result in my system.. but failed in codeforce Compiler. Any solution.. How I handle this..???

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    5 years ago, # ^ |
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    In your program you allocate an array b of length p, but then in b[(a[i]%t)] you access it as if it was an array of length t. This can fail if t > p.

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4 years ago, # |
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i am new to codeforces, can we get solutions or editorial of problems of the done contest??

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4 years ago, # |
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How can we delete an account in codeforces?

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    4 years ago, # ^ |
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    You cannot delete an account in codeforces otherwise every person who has a lower rating than the starting rating of 1500 would be tempted to delete his current account and create a new account to start afresh .

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      4 years ago, # ^ |
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      you dont need to delete your account to have a new account ! you can get new without deleting .

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        4 years ago, # ^ |
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        But members of Codeforces insult people who use multiple accounts and thus people are hesitant of creating new accounts.

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4 years ago, # |
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I really don't want to see the problem tags before I think about the problem.** How can I hide the appearance of the problem tags?** The tags have a bad influence on my independence of solving prosems.

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4 years ago, # |
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If any person does not sucessfully solved any one problem in codeforces match Will it rating changes??

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4 years ago, # |
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Is it possible to make someone's code private??

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    As far as I know, our code is public to others. We don't have access to hiding our code. I think this is very good for us to learn from others.

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4 years ago, # |
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hi i have problem with my code and i don't know it.and i want to see the answer of the question.how i can do that? where i should go(in website)?? thanks

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4 years ago, # |
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how can i perform manual hacks and how can i see at what cases is my solution hacked

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4 years ago, # |
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hello, can you help me whith write program c++ check if polygan is concave or convex?

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4 years ago, # |
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Hey Guys,
I think there is a problem with the links when you click on them they don't point to the answer I checked the page source file it seams that the id they are pointing to is not assigned to the answer <li>
Can anyone check :)

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4 years ago, # |
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how can i change handle rather than using gmail to login? or how can i delete account so i can use same email to create different account?

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4 years ago, # |
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Can i participate in div2 contest if my rating is greater than 1700 ? and vice versa ?

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4 years ago, # |
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put me minus !!!

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4 years ago, # |
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Hi,Mike Mirzayanov
I Designing some problem for contest!
How I can produce a contest in CF?
thanks

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    4 years ago, # ^ |
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    When I was blue I asked them this question and they answered "You should be at least yellow." ;)

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4 years ago, # |
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Hi everyone, I'm new here and I've met some serious problems like this one I submitted (tested in custom test) my code in c++ and it returns a wrong answer (1) but when I test my code in my compiler (codeblocks) it return the correct answer which is (2)

how does this happen ? is it my mistake or some kind of bug in my compiler or codeforces's ?

please help me !

(160A Twins)

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    4 years ago, # ^ |
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    1. You didn't initialize some of your variable (a.k.a sum)
    2. You should write questions like this on your own codeforces blog
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4 years ago, # |
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Because of some problems I had with logging in the account with ruhanhabib39 handle, I created another account(ruhan.habib39). Now I want to delete the ruhanhabib39 account. How will I delete it?(I was unable to login in that account).

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4 years ago, # |
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You may want to change Gerald to Max in this faq

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4 years ago, # |
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Is there any way to change my username?

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4 years ago, # |
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Please let me know if this is not the right place to ask questions.

I have a question about virtual contests. Me and some of my friends are planning to compete on the previous div 2 rounds. As I understand, each of us will have to simulate the virtual contest individually and then compare our results. Is there a better way for this? I mean can we create a room or group and compete there such that leaderboard or scoreboard gets updated as would happen in a real contest? I hope I made my point clear.

Help is appreciated. Thanks!

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    4 years ago, # ^ |
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    adding up one more point.. also is there an automated way to get whats my rank would have been if i had participated in the original contest.

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4 years ago, # |
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Sir, My code gave correct output in ideone online judge, but gives a different output here, what should I do, Submission id: 11656468

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4 years ago, # |
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Hi, I'm a beginner. I have solved around 40 problems. When I submit a new solution, I'm unable to view the test results. Submission id: 12004029. Could you please help? Thanks, Manohar

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4 years ago, # |
Rev. 2   Vote: I like it -6 Vote: I do not like it

Hey,

I have been noticing that in C++ I get runtime error and I don't get it in my machine. I use a 64 bit gcc 4.9.2. Please do look into this. I've tried it one ideone.com works fine.

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

Couldn't open codeforces.com in Shanghai China these days,,,,,

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3 years ago, # |
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@admin u missed the most frequently asked question in CF:

How to become red in one year/month/week/day/hour(o.O?)

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

i've got a problem that gives me an answer on my computer and with the same input it gives another answer when i send it here. the problem is kefa and park. can anybody help me please?

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

I uploaded my picture yesterday. but my photo is invisible. I don't know why. help me, please... ^^;;

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    3 years ago, # ^ |
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    wow~ My photo is visible now. Who did help me? thank you~ ^^

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3 years ago, # |
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<--- my photo thumbnail is broken. help me~

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3 years ago, # |
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What is the rating criteria?? How Does attending contests and solving problems change rating?

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

I am unable to see the image in — http://codeforces.com/contest/599/problem/A. Using a chrome browser and images in other sites even current home page for codeforce looks good. Please help

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

why i can't see the problem's photo? link here http://codeforces.com/problemset/problem/599/A

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3 years ago, # |
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What is hacking attempt? When I tried to see solution of any problem I saw "Successful hacking attempt of xyz's solution" written! What does it mean?

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3 years ago, # |
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How much space is available for any problem in the contest?

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

Hi, I am using C# but when I submit an answer that write a double value it is printed by using comma (,) instead of dot (.), resulting in WRONG_ANSWER. I use Console.WriteLine( a_double_var );

Any idea? For example, I got this when submitting #14827895:

Output
0,666666666666667
Answer
0.666667
Checker Log
wrong output format Expected double, but "0,666666666666667" found
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    3 years ago, # ^ |
      Vote: I like it +8 Vote: I do not like it

    My submission finally got accepted after I changed the output statement to:

    Console.WriteLine ( my_double_var.ToString ( "F9", CultureInfo.InvariantCulture ) );
    

    It would be better if we don't have to specify the CultureInfo explicitly though.

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

Hey, I want to use a new name with the statistic of sharpac in 2016, so how to change my name ?

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3 years ago, # |
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I changed my handle to "I_love_CC". In the profile page it's changed, but it still remains the old handle "zkx06111" in the room I was competing.

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3 years ago, # |
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Help... How to change my handle as New Year Gift? I am using Codeforces with GMail, I have no password. When trying to change it asks my password.

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3 years ago, # |
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14 JAN 2016

For the past few days I am not able to test the code in custom invocation, when I press the 'Run' button its not running at all.Even when I write something simple like cout<<8;(only this line) in c++, its not running. I am not able to submit the solution either.The page was just loading and I am getting a Toast message "waiting for codeforces.com" at the bottom left.But I checked in my friend's laptop, it was working. Is this any server problem or something else I don't know.Please help.

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    23 months ago, # ^ |
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    did you find any solution to this as i am facing the same problem

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3 years ago, # |
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The information about rating threshold between Div 1 and Div 2 is outdated. It is now 1900 instead of 1700.

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3 years ago, # |
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plz kick out the bots !!

like (not_bot_but_POT)

he is a bot

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3 years ago, # |
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I want to use password to login but I used gmail to register my account. What should I do in order to get the password ?

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

I have an issue in assessing my last submissions

MikeMirzayanov

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    3 years ago, # ^ |
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    You wrote it in C++ but the single acceptable language is J,what is the problem?

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2 years ago, # |
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@admin i just wanted to request codeforces team to improve their regular expression which give warning about syntax for ex. when we use printf("%lld",sum); then it suggest to use cout but it also give the same warning when i am using //printf("%lld",sum); so it should not warn me in this case .

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2 years ago, # |
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What'd happen if I'm unable to participate in a contest after registration?

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    2 years ago, # ^ |
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    If you don't submit any problems, it will count as if you didn't participate in the contest.

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2 years ago, # |
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is uploading your code only way to submit the answer? or os there any way we can write and submit the code on the site itself.

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    2 years ago, # ^ |
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    You can go to the submit code tab to copy paste your code there. I'd recommend against writing your code in browser, but the custom test tab allows you to write and test your code.

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2 years ago, # |
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I recently favourited a question here on codeforces by clicking the star near it. But now I forgot the problem code is there anyway to access the problem?????

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

    You can find "FAVOURITES" at the top of your profile.

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22 months ago, # |
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Is there any problem using cin.sync_with_stdio(false) and cout... cause i got runtime error on the last contest.

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22 months ago, # |
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Dear Codeforeces support team

My handle name is sai108710. This is very weird. I had created it mistakenly. I want to change it as I don't want to create a new one. How can I? I am looking for codeforces support team email address. Would anyone kindly provide it, please?

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    22 months ago, # ^ |
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    You can change your Codeforces handle once a year, usually during Christmas Holidays. So, you have to wait until December.

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      22 months ago, # ^ |
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      Hello noelnadal,

      Great to share your knowledge. Ya, I know I can change it at December but not sure on which days. On those days, does codeforces active some links/ setting to the users?

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

If I play a contest with my team member,Can I use the same code submit the question ? -- My English language is so bad that I can't find whether the rule order it.

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11 months ago, # |
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Hello. I have problem with double cola problem(code:82A) I think that the third test case is wron becuase i tired it using a pen and paper. I need help about that!?!!!;!;

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9 months ago, # |
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Hi! Are there any methodic materials to closed contests? Just to understand how to crack some problem of the past and learn from it. I am interested specific in contest 469, problem E "Binary cards". I can view solutions but would like to find some methodic explanations.

But see this question as a general one too. Thanks, Levi

Как найти методические указания по задачам прошлого? Объяснение решений? Чтобы не только соревноваться и тренироваться, но и учиться. Выше, что меня заинтересовало конкретно, но вопрос имеет и общий характер. Спасибо, Леви

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6 months ago, # |
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How can I change my nickname?

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    6 months ago, # ^ |
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    wait until January 2019.

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      6 months ago, # ^ |
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      But when I registered, it said that I could change my nickname this week.

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

How to retrieve the account number? My friend's account number was stolen by someone else a few days ago. And his password and email have been modified so he couldn't get his account. I would be very grateful if he could get your help! MikeMirzayanov

https://codeforces.com/blog/entry/61363

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

Now i have just registered for AIM Tech Round 5 but during registration i forget to click on the check box that was may be asking for interested for any job opportunities. So is there any way to go back and click on that check box again?

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

guys,i'am new here.will points be rewarded for solving psets?. what are the uses of solving those psets?. does taking part in contests the only way to get rating?.

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2 months ago, # |
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i have a problem when i want to submit a code it takes so many time and nothing appear ans i should reload the page 2 times. after that when i submit my code,the status page appear does anyone else have the same problem? what should i do?

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

Hi! Can we use materials of CodeForces in an experiment with subjects on site for research paper? What I want to do is to choose 3 or 4 questions and ask participants to solve them and monitor their solving techniques. I might need to validate the correctness of their answers through your website or on local machines.

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2 months ago, # |
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What is div.3? Here just mention the 1 and 2 division

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5 weeks ago, # |
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When I try to change photo of my profile, I see "Invalid argument to native writeImage". What does it mean? And how can I fix it?