ahmed_aly's blog

Goodbye A2 Online Judge :(
By ahmed_aly, history, 4 years ago, In English

I'm sadly announcing that a2oj.com (A2 Online Judge) will be retiring by end of 2019, I'll shut it down at midnight on New Year's Eve. It was something I took care of for about 10 years.

I'm really sorry, but I prefer not to explain my reasons, so please don't ask me why I'm doing this, it was hard enough for me to make this decision, and also please don't try to convince me to change my mind.

I'd like to say thank you to everyone who used it, and please accept my sincere apologies for shutting it down.

If you have something good to say about A2OJ (how you used it or how it helped you in any way), I'd love to read that, please send it to the following email (or in a comment here): [email protected]

Also please feel free to take a copy of any data you can access, and if you need some data in a specific format, please send your request to the following email: [email protected] (if the data isn't public, make sure to send from your registered and verified email which can access this data). I'll do my best to fulfill all requests.

Please only use the above email, because soon I'll be deactivating my personal Facebook account again, I'll also deactivate A2 Online Judge.

Edit 1: I'll keep a static version of all Ladders & Categories.

Edit 2: Here's how I generated the ladders, in case if anyone wants to implement it: https://codeforces.com/blog/entry/47442

Edit 3: A2 Online Judge is shut down now, and a static version of all ladders and categories is available. And here are some final numbers for the record:

Database numbers:

  • 24,012,628 total number of database rows.
  • 99,242 registered users.
  • 33,133 created contests.
  • 1,581,430 submissions collected from other online judges.
  • 937,658 different source codes stored in the database.
  • 261,733 compiled and executed source codes (in 54 different languages).
  • 6,144,545 user solved problem entries (detected that a user solved a problem).
  • 377,580 problems added to contests.

Google Analytics numbers:

  • 30,265,387 page views.
  • 5,252,045 sessions.
  • 1,157,668 users.

Top 10 countries from Google Analytics:

  1. India
  2. Egypt
  3. Brazil
  4. United States
  5. Bangladesh
  6. Peru
  7. Jordan
  8. Syria
  9. Colombia
  10. Bolivia
  • Vote: I like it
  • +1793
  • Vote: I do not like it

Comments Comments (90)
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4 years ago, # |
  Vote: I like it +26 Vote: I do not like it

I just started using it and sadly its retiring already. But, thanks for your 10+ years of work for newbies like me.

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    4 years ago, # ^ |
      Vote: I like it +9 Vote: I do not like it

    Mike wants online judge monopoly and he made ahmed_aly an offer he couldn't refuse.

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4 years ago, # |
← Rev. 2   Vote: I like it +9 Vote: I do not like it

is there any other sites as such which can help us like a2 online judge ahmed_aly?

and thanks for the site. I had recently started using it again

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

It's so sad to know that you will be closing the site. Good luck for your future.

Can anyone please make a Google sheet for all the ladders that are present on A2OJ.

Thanks in Advance.

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    4 years ago, # ^ |
      Vote: I like it +78 Vote: I do not like it

    I'll keep static pages of all Ladders & Categories.

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

      means there will be no updates in the website but the problems will be there

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

        Does that mean I can access those ladder, feature of problem dependency will be there or not?

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      4 years ago, # ^ |
      ← Rev. 5   Vote: I like it +160 Vote: I do not like it

      Instead of a static version of ladders. How about creating a cf group named "A2OJ" and adding all ladders under contest "Ladder Name: 20 — 2100 <= Codeforces Rating <= 2199 (by ahmed_aly)"
      It can at least replicate a similar experience and much more useful than static version.
      I̶ ̶c̶a̶n̶ ̶c̶r̶e̶a̶t̶e̶ ̶a̶ ̶g̶r̶o̶u̶p̶ ̶a̶n̶d̶ ̶p̶r̶o̶v̶i̶d̶e̶ ̶w̶i̶t̶h̶ ̶m̶a̶n̶a̶g̶e̶r̶ ̶r̶i̶g̶h̶t̶s̶ ̶i̶f̶ ̶s̶o̶m̶e̶o̶n̶e̶ ̶w̶a̶n̶t̶s̶ ̶t̶o̶ ̶v̶o̶l̶u̶n̶t̶e̶e̶r̶ ̶f̶o̶r̶ ̶t̶h̶i̶s̶ ̶j̶o̶b̶.̶

      Update 1: dmkz volunteer to add some ladders. I created a Public group if anyone wants to add ladders read How to contribute blog.

      Update 2: Access them here. Thanks to @ahmed_aly for creating a2oj platform and @dmkozyrev for creating these mashups.

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        4 years ago, # ^ |
        ← Rev. 3   Vote: I like it +75 Vote: I do not like it

        Added all ladders from 11 to 21, please check

        UPD. Added ladders from 22 to 31

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

          Thanks dmkz .

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

          The ladders are there... although there is one thing... all the questions in the ladder are from codeforces... but the question opening through your ladders open with some other link.

          This is not a problem actually ; but the issue is that other options which are attached with a problem ( example the tutorial , announcement option ) is missing. Announcement may not be that important ; but I think tutorial is.

          Plus the submission history of the problem is not the actual history of the problem ; it is not showing my previous submissions of the same problem ( If the previous submission of the problem was done through codeforces itself ).

          I don't know if the missing of tutorial option and non-availabilty of previous submissions is some bug or a feature yet to be implemented...

          But it is indeed correct that a2Oj was a life saver and by keeping it alive through some alternate form ; you guys are doing a great job... It would be nice if you could do something about the tutorial option.

          Thanks !

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4 years ago, # |
  Vote: I like it +113 Vote: I do not like it

Just a suggestion: Can the ladders be included somehow in Codeforces website. Its a really good collection of problems.

MikeMirzayanov Sir can this be done?

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

Auto comment: topic has been updated by ahmed_aly (previous revision, new revision, compare).

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4 years ago, # |
  Vote: I like it +130 Vote: I do not like it

why not giving it to someone who can care instead?

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

I was currently using it for improving my skills for div2 C and D problems. This is really a sad newss :(

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4 years ago, # |
← Rev. 2   Vote: I like it +30 Vote: I do not like it 
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4 years ago, # |
  Vote: I like it +19 Vote: I do not like it

why i am really sad ! the ladder helped me a lot and still .. i wish you can change your mind

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

I just started using it few weeks ago and its sad to know that it will be closed soon . The ladders was an awesome concept and i am very much thankful for that.

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

M3lsh..

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4 years ago, # |
  Vote: I like it +93 Vote: I do not like it

The ladders have helped me a lot in progressing (especially the feature about not being able to look at the next problem unless you ac the current one). Thanks for creating it in the first place.

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

Sad to hear this. Your site helped me and my friends a lot. I'm grateful for all the work and effort you've put in. If you decided to do so, then go ahead.

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4 years ago, # |
  Vote: I like it +9 Vote: I do not like it

seriously Why doesn't Codeforces have Sad reacts? :"(

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4 years ago, # |
  Vote: I like it +65 Vote: I do not like it

This site was super helpful for me after I finished USACO training pages. Thanks for making it :) I'm glad you're keeping a static version of the ladders/categories.

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    4 years ago, # ^ |
    ← Rev. 3   Vote: I like it -23 Vote: I do not like it

    .

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

    Could you please share some experience that you got from USACO training pages? How was it helping you to increase programming skills? I am likely to use USACO training pages.

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

      The problems are just really good quality and the tutorial pages are good for learning DS and Algos. I had already taken a class on it by the time I used the training pages but I think even if I had not it would have taught me all the necessary material.

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

Open source it.

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

It's very helpful for all programmers because there is a set of problems for all categories, Ladders are so helpful for all programmers also.

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4 years ago, # |
  Vote: I like it -116 Vote: I do not like it

vjudge >> a2oj

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

End of an era. Thanks man Ahmed

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4 years ago, # |
  Vote: I like it +93 Vote: I do not like it

Maybe you could find someone willing to host it instead.

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4 years ago, # |
  Vote: I like it -58 Vote: I do not like it

Kindly do not deactivate! I have just started using it.It is quite useful. Kindly change your mind please.

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    4 years ago, # ^ |
      Vote: I like it +87 Vote: I do not like it

    and also please don't try to convince me to change my mind.

    And I really like how this is not even an elaborate attempt to change their mind, there's no reassuring speech, no "A2OJ has been so important to many", no arguments at all, just "pls change your mind!!"

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

      There are probably so many reasons, that he couldn't list them in a single comment. :)

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

please make an excl sheet of every categories and ladder also. Thanks <3

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

F

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

Ladders help me a lot. I will miss you A2. And thanks for your contribution.

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

thanks you so much a2oj

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

how about the chances to re-run a2oj in the future?

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

I can't receive verification email,and it isn't in the spam,is it still working?

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

"I am not crying......"

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

a2oj, ffffffffffffffffffffffffffffff, please make your project open source or give someone who can care about it

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

The ladders have helped me a lot. Thank you so much a2oj we will miss you. Goodbye :(

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

My memories <3 Bye

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

Thanks for 10 years of dedication :((

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

Is it possible to create a group here in CF and then add all ladders as contests, because the problem selection in the ladders is very nice.

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4 years ago, # |
← Rev. 2   Vote: I like it +10 Vote: I do not like it

I am really very sad to hear it. It was a large online judge with problems of tasks from various sources with handy ladders & categories. Your site really helps me and my friends... Thank you for 10 years of hard work!

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

Will miss A20j badly. The ladder have helped me a lot. As you made up your mind, I will respect your decision, but its a request from whole cp community to please make your project opensource. Thank you and good bye A2oj :(

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

Can you please add the contests on the website to the Codeforces Gym? These contests have great value and many people can get benefits from them.

I'm willing to help you with this

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

Auto comment: topic has been updated by ahmed_aly (previous revision, new revision, compare).

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

“Say bye .”
"Bye Bye!"

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

Oh no!!!!!!!! That's too sad !!!!!!!!!!!!

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

can anyone please explain me what difference will occur after static version.means then also we can access problems and solve them.so what will be difference??

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

I used a2oj during last winter holiday, it helped me gain pretty much CP knowledge and win a gold medal in this year's ICPC, thanks and goodbye.

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

Bye a2oj, you were an incredible online judge and I will solve on you till the last moment

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

nooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo

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

How can I access all ladders' problems without solving all of them?

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4 years ago, # |
  Vote: I like it -13 Vote: I do not like it

apolgy for bad english

where were u wen a2oj die

i was at house eating dorito when phone ring

"a2oj is kil"

"no"

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

where is the static version of ladders?

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

how to access the static version of ladders now?

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

Auto comment: topic has been updated by ahmed_aly (previous revision, new revision, compare).

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4 years ago, # |
  Vote: I like it +27 Vote: I do not like it

A2oj is up again, is this permanent?

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

ahmed_aly , is A2OJ reactivated again permanently??

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

A2oj is up and runnig ...wow that's something you want to hear in a pandemic :D

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

    But the database is cleared I think as My old username is not working.! UPD everything is working fine I was confused between passwords , sorry!

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

      I dont think so. My old username is working as well all the problems I have solved via a2oj are visible

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

ahmed_aly What happened to old ladders of Div 2 of 100 questions each. I was using them?

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

If you cannot see the ladder that corresponds with your current progress: https://github.com/rishabhdeepsingh/A2OJ-Ladder/tree/master/ladders

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

I think its back but when i solve questions on Codeforces its not getting updated.

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

Good news A20j is back (today — 05-11-21).

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