Search found 172 matches

by Zzzz
Mon Mar 28, 2011 7:31 pm
Forum: Combinatorics
Topic: Probability: coin toss
Replies: 7
Views: 3191

Re: Probability: coin toss

A valid sequence is a sequence of tosses which doesn't contain a pair of consecutive heads. Lets define three sequences : i) $T_1=2,\ T_2=3,\ T_{i+2}=T_{i+1}+T_i$ i) $t_1=1,\ t_2=2,\ t_{i+2}=t_{i+1}+t_i$ i) $h_1=1,\ h_2=1,\ h_{i+2}=h_{i+1}+h_i$ Notice that if the coin is tossed for $k$ times, the nu...
by Zzzz
Sun Mar 27, 2011 6:47 pm
Forum: Geometry
Topic: Game of pool? (own)
Replies: 6
Views: 2937

Re: Game of pool? (own)

I will explain my solution later (Sorry... actually I don't have enough time to write it right now :( )

I just want to be sure about the solution. Is it
$\theta \in \{ \alpha : tan\ \alpha$ is rational $\}$
?
by Zzzz
Mon Feb 21, 2011 6:49 pm
Forum: Secondary Level
Topic: Circle is symetric about diameter
Replies: 11
Views: 4761

Re: Circle is symetric about diameter

the reflection of A and B are ACP and BCQ. Actually the term 'reflection' is almost same as physics as Moon vai said. So the reflection of a man will be a man, a tree will be a tree, a line will be a line, a point will be a point. Probably you didn't mean reflection here. Please attach a photo (you...
by Zzzz
Thu Feb 17, 2011 8:39 am
Forum: Secondary Level
Topic: Circle is symetric about diameter
Replies: 11
Views: 4761

Circle is symetric about diameter

Easy to prove but interesting :
$A$ and $B$ are two points on a circle and $C$ is a point on diameter $MN$ such that $\angle ACN=\angle BCN$
Prove that $AC=BC$
by Zzzz
Wed Feb 16, 2011 7:48 pm
Forum: Computer Science
Topic: number of common divisors
Replies: 4
Views: 2394

Re: number of common divisors

আমি জানি না এইটা কাজ করবে কিনা। তবে চেষ্টা করে দেখা যায়। একটা সংখ্যা যদি a,b কে করে তাইলে তাদের gcd কেউ ভাগ করবে। input দেওয়া সংখ্যা ২ টার gcd বের করে তার উৎপাদক সংখ্যা বের করা যায়। এক্ষেত্রে আরকি একটা সংখ্যার prime power factorization করা লাগতিসে, আগে যেখানে ২ টা সংখ্যার করা লাগতো। gcd বের করতে ...
by Zzzz
Sat Feb 12, 2011 6:59 am
Forum: International Olympiad in Informatics (IOI)
Topic: National Informatics Olympiad 2011
Replies: 21
Views: 11224

Re: National Informatics Olympiad 2011

2010 e HSC dise ba tar por HSC dibe emon sobai allowed.

btw, chorom boka ta ke?
by Zzzz
Wed Feb 09, 2011 9:23 pm
Forum: International Olympiad in Informatics (IOI)
Topic: National Informatics Olympiad 2011
Replies: 21
Views: 11224

Re: National Informatics Olympiad 2011

হুম, তবে আশার (বা দুরাশার) কথা হইল বেশি লোকজন উৎসাহী না :P
HandaramTheGreat wrote:সবকিছু শেষ হতে আনুমানিক ক'টা বাজতে পারে?
গতবার ৪.৩০ টার দিকে result দেয়া হইছিল মনে হয়...
by Zzzz
Wed Feb 09, 2011 1:42 pm
Forum: International Olympiad in Informatics (IOI)
Topic: Algorithms
Replies: 9
Views: 5502

Algorithms

Can anyone suggest some useful algorithms? For example, I have just learned Dijkstra's algorithm.

If possible please give some links also.

Important: Please don't think that, Zzzz probably knows this 'easy and wellknown' algorithm, so I need not to suggest it.
by Zzzz
Wed Feb 09, 2011 7:03 am
Forum: International Olympiad in Informatics (IOI)
Topic: National Informatics Olympiad 2011
Replies: 21
Views: 11224

Re: National Informatics Olympiad 2011

not only problem set, a computer also should be provided to each of them :roll:
by Zzzz
Tue Feb 08, 2011 8:35 pm
Forum: Secondary Level
Topic: Prove P is prime
Replies: 7
Views: 3085

Prove P is prime

If $P$ divides $(P-1)!+1$, prove that $P$ is a prime.