2
votes
4answers
68 views

determining the amount of total questions needed in a game given the probabilty

I'm creating a game and can't seem to quite figure this out - driving me crazy. There are 8 questions in my game You can play the game an unlimited amount of times the test bank doesn't change. so ...
1
vote
0answers
242 views

Finding the number of arrangement of N people of different height such that K of them are visible from front

Moderator Note: This is a current contest question on codechef.com. [Initially, I had asked this question in stackoverflow, but someone suggested to post it here, and hence this question is ...
1
vote
2answers
175 views

France Olympiad Team Selection Test 2005

In an international meeting of n ≥ 3 participants, 14 languages are spoken. We know that: - Any 3 participants speak a common language. - No language is spoken by more than half of the participants. ...
1
vote
0answers
194 views

Modular arithematic Equation

We have an equation: $a^x+b^x+c^x \equiv m \pmod n $ also given $a,b,c < y $ what are the total number of solutions of this equation?
0
votes
0answers
41 views

Question based on counting. [duplicate]

Given two integers $N$ and $M$, find how many permutations of $1, 2, ..., N$ (first $N$ natural numbers) are there where the sum of every two adjacent numbers is at most $M$
0
votes
1answer
924 views

How many permutations of $N$ number that sum of every two adjacent is at most $M$

Moderator Note: This is a current contest question on codechef.com. This codechef.com contest ended on $17$ June. —Brian M. Scott Given two integers $N$ and $M$, find how many permutations ...
1
vote
0answers
107 views

How many ways to fill the $N \times N$ board by nonnegative integers, such that sum of the numbers of each row and each column is $R$?

How many ways to fill the $4 \times 4$ board by nonnegative integers, such that sum of the numbers of each row and each column is $3$? I wrote a brute-force and got $2008$ which seems to be the ...