## Solving regional BdOI Dhaka-2013

Discuss everything related to IOI here. For more general or advanced topics use CS forum.

Moderators: bristy1588, Labib

nafistiham
Posts: 829
Joined: Mon Oct 17, 2011 3:56 pm
Location: 24.758613,90.400161
Contact:

### Solving regional BdOI Dhaka-2013

Informatics regionals are over. So, I suggest we should talk about the problems. I would be glad to post those problems, if they were not that much big.
I wish someone could post any pdf version of the problem set.
$\sum_{k=0}^{n-1}e^{\frac{2 \pi i k}{n}}=0$
Using $L^AT_EX$ and following the rules of the forum are very easy but really important, too.Please co-operate.

kfoozminus
Posts: 33
Joined: Mon Nov 26, 2012 4:52 pm
Contact:

### Re: Solving regional BIOC Dhaka-2013

there was same question in all divisions, and hey... it's BdOI, not BIOC(it actually means Bangladesh Informatics Olympiad Committee)

এক জন যদি একটা করে পোস্ট করে তাহলেই তো দশটা হয়ে যায়... i'm posting number 10(oh yeah! i liked it!)

$10.$ $n$ pigeonholes are kept side by side in a row. you want to put pigeons in some of the holes in a way that for every $k$ consecutive holes there will be exactly $m$ holes with a pigeon. There shouldn't be more than one pigeon in a hole.

For example,
For $n=4$, $k=3$, $m=2$, a solution can be $PP.P$(here $P$ means a pigeon and $.$ means a hole), but $.PPP$, $PPP.$, $P.P.$ or $PP..$ aren't solutions.

$1.$ write a general formula to find the number of solutions for $n$, $m$ and $k$
$2.$ $n=5$, $k=3$, $m=2$
$3.$ $n=1000000000$, $k=30$, $m=25$

*Mahi*
Posts: 1175
Joined: Wed Dec 29, 2010 12:46 pm
Location: 23.786228,90.354974
Contact:

### Re: Solving regional BIOC Dhaka-2013

kfoozminus wrote: $10.$
Hint:

Use $L^AT_EX$, It makes our work a lot easier!

*Mahi*
Posts: 1175
Joined: Wed Dec 29, 2010 12:46 pm
Location: 23.786228,90.354974
Contact:

### Re: Solving regional BdOI Dhaka-2013

You can get the PDF question paper in this topic.

Use $L^AT_EX$, It makes our work a lot easier!

Labib
Posts: 411
Joined: Thu Dec 09, 2010 10:58 pm
Contact:

### Re: Solving regional BdOI Dhaka-2013

Anyone help me with the solution of number 6??
Please Install $L^AT_EX$ fonts in your PC for better looking equations,
Learn how to write equations, and don't forget to read Forum Guide and Rules.

"When you have eliminated the impossible, whatever remains, however improbable, must be the truth." - Sherlock Holmes

*Mahi*
Posts: 1175
Joined: Wed Dec 29, 2010 12:46 pm
Location: 23.786228,90.354974
Contact:

### Re: Solving regional BdOI Dhaka-2013

Labib wrote:Anyone help me with the solution of number 6??
The solution is quite straightforward.
1. Send the largest element of the $k$ element stack at the end with at most two 'reverse' moves.
2. Continue with the $k-1$ element stack.

Use $L^AT_EX$, It makes our work a lot easier!

Fatin Farhan
Posts: 75
Joined: Sun Mar 17, 2013 5:19 pm
Contact:

### Re: Solving regional BdOI Dhaka-2013

how can i start learning programming

*Mahi*
Posts: 1175
Joined: Wed Dec 29, 2010 12:46 pm
Location: 23.786228,90.354974
Contact:

### Re: Solving regional BdOI Dhaka-2013

Fatin Farhan wrote:how can i start learning programming
Use $L^AT_EX$, It makes our work a lot easier!