Hello Codeforces!

The first round of BubbleCup 11 started! It will last until April 26th 14:00 CET. Create a team, collaborate and start solving problems early to increase your chance of qualifying for the Bubble Cup Finals. Before the Finals, there is a second round (on which depends whether you are invited to the BubbleCup Finals), and all teams from round 1 are invited. Exact date of the finals is 22nd September and it will be held in Belgrade, Serbia.

New Due to increase in Python popularity on programming competitions, including ACM, submissions in Python 2 and 3 are now also supported.

Official link of the competition: http://bubblecup.org/

Good luck and try to have some fun!

Hello Codeforces!

As you may know, the official site of BubbleCup has been updated traditionally.

Registration for Bubble Cup 11 opens on March 26th alongside test round — Round 0!

While you wait for Bubble Cup to start please check out our new Rules page for more info about this year's competition format changes.

Official link: http://www.bubblecup.org/

Hope to see you and wish you good luck!

Hello CodeForces!

I know this question isn't for this site, but I don't have a better place to ask. What are some good and useful number theory defintions and theorems? I need some for high school competition. I would appreciate if you can help me, at least names or links, no need for declaration and the statement.

Thanks!

Hello frends from CFS(CodeForces)!

Hir are some of the bestest optimizations that will get your rating jump to th clouds!!1!! I use them every single time beliv me!

1) Use BFS aka BruteForce. First thing you need to do when you do some problem is use BFS!! Dat will save you from: Terminated signal 1e+27387282, WA, TLE, MLE, CE, RTE, BQE...

2) When you wait in queue for long time, just agressivly press Alt + F4 few times. There will be queue no more gut frend. You will be advantage, thank mi later babe.

3) Before the contest you MUST pray to MAJKAMirzayanov. MajkaMirzayanov is the mother of the almighty MikeMirzayanov! Note: Majka is read Mike — a in Serbian, Russian, etc... Thank to that godess we hav our savior MikeMirzayanov frends!!! Btw his worst enemy is bad gredaer.

4.41423568) If you want to know everything ju should watch those Indian guys/girls on YT(youtube) who intrduce themselves as 419NigerianPrince or PussyDestroyerIndia(Im nut talking about pussy cats).

5) Use bitset. For more details visit: http://mirror.codeforces.com/blog/entry/53168. Thank you for the blessing my mriemd frind :D

That is it. It works, b4 u downvote just ask my frends: Sprdalo00, Sprdalo01, Sprdalo02,...Tosic, KlzX, ivan100sic, ....etc

GG EZ M8 W8 B4 U H8 I R8 8/8 See ya frends.

Hi CodeForces!

Recently, I've started doing contests on CodeForces and when my rating jumped I was obsessed with contests, ratings,.... I was wondering how do rating changes, is there any rule, or is there any formula... And after some research, I found this site:http://mirror.codeforces.com/blog/entry/102.

I was discussing with my pals about one interesting thing, you can not(obviously it is possible) get rating change 0. I mean, there is a very little chance for you to break the formula and get infinity(and beyond!).

I thought that if someone succeed in breaking the formula, CodeForces would give him +1 or -1 or some similar value, oh boy was I wrong! When I finished my last contest (Div 2. #442), which I did terribly (solved only problem A, (average for me is B and sometime C) and one hack), I was waiting for results. The NoButtHurt extension didn't work on me, I thought okay bug, it happens... My friends got their results (and rating change) and I didn't. I was waiting and waiting and waiting...I mean there was a 0 but I thought that I am still in queue for calculating. Next morning my rating didn't changed, wow! I was shocked(so was my friends). Still trying to figure it out, did I "broke: the formula and got 1/0 rating change or idk.... Does anyone have any clue what happened? Maybe it's usual thing, did you ever got rating changed by 0?