By cheater_killer, history, 27 hours ago, In English,

Today while hacking I came across the following solutions by amitgomi and Born_Confused

53149949 and 53156694 which are exactly same, the variable "tes" is added by amitgomi to avoid plagiarism.

And I further noticed that they had been doing this in a lot of contests.

The culprits involved are from the same college/organisation(IIIT Lucknow) : amitgomi, Born_Confused and the_phoenixx.

I found these 6 cases in the past 10-12 contests alone( probably more if we look into more past rounds ) :

These are just the ones which can be seen clearly are copied from one another. I have ommitted submissions which are very similar (like these 52702208 and 52707014 (change of flow) from 551 Div2) which I highly suspect are copied as well.

In such cases of continued cheating shouldn't the accounts be banned?

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By PikMike, history, 19 hours ago, translation, In English,

1155A - Reverse a Substring

Solution (Vovuh)

1155B - Game with Telephone Numbers

Solution (Roms)

1155C - Alarm Clocks Everywhere

Solution (Vovuh)

1155D - Beautiful Array

Solution (PikMike)

1155E - Guess the Root

Solution (adedalic)

1155F - Delivery Oligopoly

Solution (BledDest)

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By Lewin, history, 4 days ago, In English,

Here's the tutorial. Code can be found in this link:

Love A
Hate A
Tree Diameter
Frog Jumping
Hot is Cold
Leaf Partition
Zoning Restrictions
Satanic Panic

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By InuyamaAoi, history, 32 hours ago, In English,

If you clicked my profile, you can know that my e-mail account registered in Codeforces is, which is both valid(according to RFC822) and quite exotic. (I personally like that term where I got response from SPOJ Forum, when I said that their system cannot my valid e-mail address.)

You might feel some anime addict bought a strange e-mail address, and yes it is.

I think that some of system do not see this as valid e-mail address, most of reason is that life contains 4 character, which makes lots of inconvenience situation to me.

For example, my university mail system is configured to receive mail only matching regex /^[0-9a-zA-Z]([-_\.]?[0-9a-zA-Z])*@[0-9a-zA-Z]([-_\.]?[0-9a-zA-Z])*\.[a-zA-Z]{2,3}$/i, which cannot accept e-mail address containing + character, life domain, and so on.

I think I cannot receive an e-mail including Codeforces. My another email account, equally configured with can receive mail. I did not noticed it quite long, but once I tried to log in polygon, it says me to check e-mail inbox, and I cannot receive an e-mail. (Sure, I checked a spam mail box)

I just want to ask Codeforces to check this issue, and if you are developing e-mail-related system, just want you to think a little about weird anime addict using exotic e-mail address using (You can use RFC822 standard anyway)

UPD: I think issue in codeforces was fixed. Thanks in advance.

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By Luma, history, 3 days ago, In English,

Hello Codeforces!

I made the user script to append the form to submit on Codeforces problem pages.

Sorry, this supports only modern browsers like Chrome and Firefox.

greasyfork link :


Install UserScript runner like Tampermonk and Greasymonkey to your browser.

(Sorry, I couldn't make it work well with Greasymonkey.)

Then, open install link and click install.


You can use it as you can see it on the submit page's form.


  • Support contest, gym and problemset problem pages.
  • Problem selection will be auto-selected and disabled. Problem ID is calculated from URL.
  • This tool gets form from the submit page using Ajax.
  • This tool never connect the other site.
  • If we open the submit page right away after the contest starts, we can't select the problem ID (because there's no option somehow).
    But don't worry. This script automatically retry if there's no option.
  • If 30 minutes left and you submit, this script automatically re-generate the form because sometimes the token expires.
    This script will drop neither your code nor file selection.


I implemented it as not disturbing users.

If you found some technical issues, rights issues or something anxious, please let me know that.

I welcome any feedback! (You know vs.? Please share in comments!)

Disclaimer of warranty

Use of this tool is at your sole risk. In no event will I be reliable to any party for any damages of any type.



Great. So cool.

This tool is here thanks to Codeforces.

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By aditya123garg, history, 27 hours ago, In English,

Hey Guys, My solution to the third problem of yesterday's round(Educational Round 63) fails on test case 20 according to Codeforces compiler but I am getting the correct answer on my own compiler and even on dry running it by myself.

Question link :-

Solution link :-

Test case on which it is failing :

2 1 10000000000 20000000000 10000000000

Plzz Guys see to it what's happening here !!

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By TripleM5da, history, 3 days ago, In English,

How to solve A and L?

Also what is D's judge solution, I am not sure if mine was the intended one.

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By T1duS399, history, 6 days ago, In English,

Greetings Codeforces community!

You all are invited to participate in CodeChef’s April Cook-Off sponsored by ShareChat. This is a short contest with 7 problems on offer. The problem statements will be available in English, Hindi, Bengali, Russian, Mandarin and Vietnamese.

ShareChat — our contest sponsor is seeking both interns and full-time employees to join their dynamic team. Job opportunities are open to programmers across the world and internship opportunities are exclusively aimed at final year B.Tech students who have already been placed and looking forward to gaining startup experience. Visit the contest page for more details.

I hope you will join your fellow programmers and enjoy the contest problems. Joining me on the problem setting panel are:
- Setters: T1duS399 (Udit Sanghi), Farhod_Farmon (Farhod Khakimiyon), Kerim.K (Kerim Kochekov)
- Tester: teja349 (Teja Vardhan Reddy)
- Editorialist: adamant (Alexander Kulkov)
- Statement Verifier: Xellos (Jakub Safin)
- Mandarin Translator: huzecong (Hu Zecong)
- Vietnamese Translator: Team VNOI
- Russian Translator: Fedosik (Fedor Korobeinikov)
- Bengali Translator: solaimanope (Mohammad Solaiman)
- Hindi Translator: Akash Shrivastava

Contest Details:

  • Start Date & Time: 21st April 2019 (2130 hrs) to 22nd April 2019 (0000 hrs). (Indian Standard Time — +5:30 GMT) — Check your timezone
  • Contest link:
  • Registration: You just need to have a CodeChef handle to participate. For all those, who are interested and do not have a CodeChef handle, are requested to register in order to participate.
  • Prizes: Top 10 performers in Global and Indian category will get CodeChef laddus, with which the winners can claim cool CodeChef goodies. Know more here:

(For those who have not yet got their previous winning, please send an email to

Good Luck!

Hope to see you participating!!

Happy Programming!!

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By ultranoobs, history, 34 hours ago, In English,

i am stuck with this dp problem , can any someone explain me the state of dp for this problem ? problem link is Question

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By danft, history, 17 hours ago, In English,

Posting on behalf of the DOMjudge developers.

Upcoming Sunday 28 April 2-7pm CEST (12-15h UTC) we will host an online contest to test our latest release of the open-source DOMjudge contest control system. The problems are not new, but selected from previous European ICPC contests.

Everyone is invited to join and compete. Register at:

We might limit the contest to the first 200 registered participants to guarantee judging capacity, but are looking into expanding this.

Please report any bugs/issues either through a clarification during the contest, or anytime later as an issue on GitHub[1] or on Slack[2].



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