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Get ranking of a combination
I have the numbers pulled without replacement from the set [1 2 3 4 5 6 7 8 9 10 11 12 13]; They are then ordered from least to...

6 years ago

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Numbered lottery balls into cells
You are running a lottery, and have a number of different balls numbered 1 to N. Your job is to figure out how many different w...

6 years ago

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A (wrong) place for everything, and everything in its (wrong) place
You have an equal number of cups and balls, each labelled from one to N. You randomly place one ball in each cup. Determine th...

6 years ago

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Put m balls into n boxes (again)
According to <http://www.mathworks.com/matlabcentral/cody/problems/1516-put-m-balls-into-n-boxes Cody Problem 1516>, if I put 3 ...

6 years ago

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Put m balls into n boxes
Can you find all the cases where, if I put 3 balls into 2 boxes the case is 1 1 1 1 1 2 1...

6 years ago

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Possible Outcomes of American Roulette
The payout for American roulette can be calculated by: payout = (38/n)-1 where n is the number of squares the bet covers. ...

6 years ago

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Which permutation is it?
Let write some permutations of positive integers. 1: 1 2 3 4 5 6 ... 2: 2 1 3 4 ... 3: 1 3 2 4 ....

6 years ago

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N-th permutation.
Let write some permutations of positive integers. 1: 1 2 3 4 5 6 ... 2: 2 1 3 4 ... 3: 1 3 2 4 ... ...

6 years ago

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Goldbach's marginal conjecture - Write integer as sum of three primes
Goldbach's strong conjecture states that every even integer greater than 2 can be expressed as the sum of two primes. For exampl...

6 years ago

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Prime Ladders
A <http://en.wikipedia.org/wiki/Word_ladder word ladder> transforms one word to another by means of single-letter mutations. So ...

6 years ago

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Numbers spiral diagonals (Part 2)
Inspired by Project Euler n°28 and 58. A n x n spiral matrix is obtained by starting with the number 1 and moving to the righ...

6 years ago

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Twins in a Window
<http://en.wikipedia.org/wiki/Twin_primes Twin primes> are prime numbers that differ by 2, such as [11,13] or [41,43]. Write a f...

6 years ago

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Twin Primes
Twin primes are pairs of primes that are immediately next to each other (difference of two). The lesser of twin primes are 3, 5,...

6 years ago

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Generalised Hamming Number
Inspired by Project Euler n°204 and Problem 1308 by James A generalised Hamming number of type n, has no prime factor larger ...

6 years ago

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Find vampire numbers
A <http://en.wikipedia.org/wiki/Vampire_number vampire number> is a number v that is the product of two numbers x and y such th...

6 years ago

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Numbers with prime factors 2, 3 and 5.
Make a function which takes one positive integer n and returns a matrix with the numbers of the form (2^i)*(3^j)*(5^k) which are...

6 years ago

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Proper Factors
Generate the proper factors of input integer x and return them in ascending order. For more information on proper factors, refer...

6 years ago

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Multiples of a Number in a Given Range
Given an integer factor _f_ and a range defined by _xlow_ and _xhigh_ inclusive, return a vector of the multiples of _f_ that fa...

6 years ago

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Project Euler: Problem 3, Largest prime factor
The prime factors of 13195 are 5, 7, 13 and 29. What is the largest prime factor of the number being input, input might be ui...

6 years ago

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Smith numbers
Return true if the input is a Smith number in base ten. Otherwise, return false. Read about Smith numbers at <http://en.wikipedi...

6 years ago

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Get all prime factors
List the prime factors for the input number, in decreasing order. List each factor. If the prime factor occurs twice, list it as...

6 years ago

Solved

Factorize THIS, buddy
List the prime factors for the input number, in decreasing order. List each factor only once, even if the factorization includes...

6 years ago

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jogging?
Imagine x-y coordinate system and you are at the origin and your partner is on the x-axis at some small distance (d) away from y...

6 years ago

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Mechanics 1
I thought I would make a mechanics problem for all those physics lovers out there. Imagine two solid, rigid spheres B1 and B...

6 years ago

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Bouncing disk
A disk is placed in a rectangular room with dimensions a and b in a point with coordinates x0 and y0. The disk is given a startu...

6 years ago

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Find the jerk
No, it's not the author of this problem... Jerk is the rate of change in acceleration over time of an object. So, if given t...

6 years ago

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Juggling
There is a notation system for <http://en.wikipedia.org/wiki/Juggling jugglers> called <http://en.wikipedia.org/wiki/Siteswap si...

6 years ago

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What gear ratio does the cyclist need?
A cyclist (perhaps including our famed Codysolver the cyclist <http://www.mathworks.com/matlabcentral/cody/players/1841757-the...

6 years ago

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Mechanical Advantage of a Gear Train
Calculate the mechanical advantage of a gear train. The mechanical advantage of a gear couple is given by MA = T_o/T_i where ...

6 years ago

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Determine if a four bar mechanism is of Grashof type
A four bar mechanism is composed of four links. if s is the smallest link, l the longest and p,q are the length of the other lin...

6 years ago