### nerd's blog

By nerd, 10 years ago, translation,

Hi there!

Is it necessary to know regular expressions in competitive programming? If yes, then is there any good tutorial?

Thanks

• +5

By nerd, 12 years ago,

Dear All,

How to access to i*th element of a set in c++ effectively (*O(1) or (logN))?

Thanks

• +1

By nerd, 12 years ago,

Hi everybody!

I have one question related with Polygon System (codecenter.sgu.ru/polygon)

Is there any limit in memory while uploading zip-archive file of tests?! even if it will be 300Mb?

• -5

By nerd, 13 years ago, translation,
Equation of a line in two dimensional plane is ax + by + c = 0

How to find coefficients {a, b, c}?

We can find them by simplifying and modifying this:

after:

(x - x1)(y2 - y1) = (y - y1)(x2 - x1)

x(y2 - y1) - x1(y2 - y1) = y(x2 - x1) - y1(x2 - x1)

(y2 - y1) * x + (x1 - x2) * y + y1(x2 - x1) + x1(y2 - y1) = 0

a = y2 - y1
b = x1 - x2
c =  - by1 - ax1

It is all...
• 0

By nerd, 13 years ago, translation,

Hi everybody!

Who knows where can I find videolections in dynamic with profile(that is by using bitwise operations and etc., something like mask)

Thanks...

• 0

By nerd, 13 years ago,
When and where problems from current Petrozavodsk 2011 will be available to solve?!
And where I can find previous years problems?!

thanks.
• 0

By nerd, 13 years ago,

In which problems we can use solving System of algebraic linear equations, such as by Gauss' method?

Is there any problems(not theoretical)?

• 0

By nerd, 13 years ago,

 The night of qadr is the most virtuous night of the year.  Allaah says in the Quran (what means):“We revealed it on the night of power [that is, qadr]." "What will tell you what the night of power is? It is better than a thousand months” [97:1-3] Any action, for example, reciting the Quran, making remembrance of Allaah, and so on, on the night of qadr is better than the same act performed for one thousand months.

### P.S. Please, let's comment without any discrimination of religions.

P.S.S. Sorry for my poor english.

• 0

By nerd, 13 years ago,

## Let's watch Football match

Who can predict result of this match by using combinatorial formulas???
• 0

By nerd, 13 years ago,
Who knows, where i can run any program, for example:
I wrote in C++ program, which checks, if number N is prime or not.
Then I have *.exe/*.sh file. Is there any web sites, where i can run that file, and server in that site is fast.
For example, in ideone.com how many operations done in one second, i mean speed of CPU.
So, is there any sites, where we can run our program, and speed of CPU in server of site is too fast, so that 109-1010 operations work in 1 - 2 seconds.

thanks...
• +12

By nerd, 13 years ago, translation,

phi(N) = euler's function = x

how we can find N, when we are given x. let's name it like phi_inv(x) = N

for example:

phi_inv(4) = 5, because phi(5) = 4.

x ≤ 1010
• +3

By nerd, 13 years ago,

WELCOME To Everyone!!!

Recently I've learned MaxFlow, MinCostMaxFlow and Matching...

Where can I solve problems in matching?

Thanks...

• +10