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Solving regional BdOI Dhaka-2013

Posted: Fri Dec 28, 2012 8:43 pm
by nafistiham
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.

Re: Solving regional BIOC Dhaka-2013

Posted: Fri Dec 28, 2012 10:22 pm
by kfoozminus
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 $k$
$2.$ $n=5$, $k=3$, $m=2$
$3.$ $n=1000000000$, $k=30$, $m=25$

Re: Solving regional BIOC Dhaka-2013

Posted: Fri Dec 28, 2012 10:57 pm
by *Mahi*
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?

Re: Solving regional BdOI Dhaka-2013

Posted: Sat Dec 29, 2012 11:03 am
by *Mahi*
You can get the PDF question paper in this topic.
http://www.matholympiad.org.bd/forum/vi ... =32&t=2529

Re: Solving regional BdOI Dhaka-2013

Posted: Wed Jan 02, 2013 3:32 pm
by Labib
Anyone help me with the solution of number 6??

Re: Solving regional BdOI Dhaka-2013

Posted: Wed Jan 02, 2013 7:11 pm
by *Mahi*
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.

Re: Solving regional BdOI Dhaka-2013

Posted: Tue Mar 19, 2013 10:19 am
by Fatin Farhan
how can i start learning programming :idea:

Re: Solving regional BdOI Dhaka-2013

Posted: Tue Mar 19, 2013 7:23 pm
by *Mahi*
Fatin Farhan wrote:how can i start learning programming :idea:
http://www.matholympiad.org.bd/forum/vi ... =34&t=1580