Solving regional BdOI Dhaka-2013

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

Moderators: bristy1588, Labib

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

Solving regional BdOI Dhaka-2013

Unread post by nafistiham » Fri Dec 28, 2012 8:43 pm

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.
Introduction:
Nafis Tiham
CSE Dept. SUST -HSC 14'
http://www.facebook.com/nafistiham
nafistiham@gmail

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

Re: Solving regional BIOC Dhaka-2013

Unread post by kfoozminus » Fri Dec 28, 2012 10:22 pm

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 $k$
$2.$ $n=5$, $k=3$, $m=2$
$3.$ $n=1000000000$, $k=30$, $m=25$

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

Re: Solving regional BIOC Dhaka-2013

Unread post by *Mahi* » Fri Dec 28, 2012 10:57 pm

kfoozminus wrote: $10.$
$n$ 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 $k$
$2.$ $n=5$, $k=3$, $m=2$
$3.$ $n=1000000000$, $k=30$, $m=25$
Hint:
First think you have completed putting pigeons in the first $k$ holes. How do you (or in how many ways can you) fill up the $k+1^{th}$ hole?
Please read Forum Guide and Rules before you post.

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

Nur Muhammad Shafiullah | Mahi

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

Re: Solving regional BdOI Dhaka-2013

Unread post by *Mahi* » Sat Dec 29, 2012 11:03 am

You can get the PDF question paper in this topic.
http://www.matholympiad.org.bd/forum/vi ... =32&t=2529
Please read Forum Guide and Rules before you post.

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

Nur Muhammad Shafiullah | Mahi

User avatar
Labib
Posts: 411
Joined: Thu Dec 09, 2010 10:58 pm
Location: Dhaka, Bangladesh.
Contact:

Re: Solving regional BdOI Dhaka-2013

Unread post by Labib » Wed Jan 02, 2013 3:32 pm

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

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

Re: Solving regional BdOI Dhaka-2013

Unread post by *Mahi* » Wed Jan 02, 2013 7:11 pm

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.
Please read Forum Guide and Rules before you post.

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

Nur Muhammad Shafiullah | Mahi

User avatar
Fatin Farhan
Posts: 75
Joined: Sun Mar 17, 2013 5:19 pm
Location: Kushtia,Bangladesh.
Contact:

Re: Solving regional BdOI Dhaka-2013

Unread post by Fatin Farhan » Tue Mar 19, 2013 10:19 am

how can i start learning programming :idea:

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

Re: Solving regional BdOI Dhaka-2013

Unread post by *Mahi* » Tue Mar 19, 2013 7:23 pm

Fatin Farhan wrote:how can i start learning programming :idea:
http://www.matholympiad.org.bd/forum/vi ... =34&t=1580
Please read Forum Guide and Rules before you post.

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

Nur Muhammad Shafiullah | Mahi

Post Reply