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Extra safe primes
Did you know that the number 5 is the first safe prime? A safe prime is a prime number that can be expressed as 2p+1, where p is...

3 days ago

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

3 days 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 ...

3 days 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...

3 days 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.wikipedia...

3 days ago

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Prime factor digits
Consider the following number system. Calculate the prime factorization for each number n, then represent the prime factors in a...

3 days ago

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"Low : High - Low : High - Turn around " -- Create a subindices vector
Let two vectors *lo* and *hi* be given. The job is to create a index vector like so idx = [lo(1):hi(1) lo(2):hi(2) ...]...

3 days ago

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Matrix indexing with two vectors of indices
Given a matrix M and two index vectors a and b, return a row vector x where x(i) = M(a(i),b(i)).

3 days ago

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Put two time series onto the same time basis
Use interpolation to align two time series onto the same time vector. This is a problem that comes up in <http://www.mathwork...

3 days ago

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Reindex a vector
You are given two vectors of equal length. Vector N has numeric values (no Inf or NaN) while vector IDX has integers. Place th...

3 days ago

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Joining Ranges
You are given a n-by-2 matrix. Each row represents a numeric range, e.g. x = [0 5; 10 3; 20 15; 16 19; 25 25] contains...

3 days ago

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Fill a zeros matrix
The aim is to fill an array of all zeros given a numerical value and the index of row and columns for this value. 3 Inputs: ...

3 days ago

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Replace May with April
For instance, if the input is input_str = 'The flowers may bloom in April'; then the output is output_str = 'The flo...

3 days ago

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commutative?
Given the handle to a binary function that takes two ordinary numbers, test if the function is commutative.

3 days ago

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root?
* Given a function 'foo', and a position 'there', find the root near 'there'. * For example: If foo=@sin, and there=3.1, then r...

3 days ago

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Find files with extension ext in the current directory
List all files with extension 'ext' in the current directory. Return a char matrix with the name of files in rows. Return 0 if...

3 days ago

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Evil Number
Check if a given natural number is evil or not. Read more at <https://oeis.org/A001969 OEIS>.

3 days ago

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Find Missing Number
A little problem (inspired by CodeChef) for the coffee break. A friend give you an array of size n-1 integers and these int...

3 days ago

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nth Rational Number
Return the nth rational number. This is the inverse to Problem 1471. Index of a Rational number The first ten positive rationa...

3 days ago

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Is this number Munchhausen?
In this problem, simply return 1 if a supplied number is Munchhausen or 0 if not. Example 153 is narcissistic but not a Munchh...

3 days ago

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Narcissistic number ?
Inspired by Problem 2056 created by Ted. In recreational number theory, a narcissistic number is a number that is the sum of ...

3 days ago

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Find the two-word state names
Given a list of states, remove all the states that have two-word names. If s1 = 'Alabama Montana North Carolina Vermont N...

3 days ago

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Animated GIF Creator
This Challenge is to execute the Function Template which has a fully functional Animated GIF creator of a shape related to a Zer...

3 days ago

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Volume of a Parallelepiped
Calculate the volume of a Parallelepiped given the vectors for three edges that meet at one vertex. A cube is a special case ...

3 days ago

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Polite numbers. N-th polite number.
A polite number is an integer that sums of at least two consecutive positive integers. For example _7 = 3+4_ so 7 is a polite...

3 days ago

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Figurate number triangle
Check whether the input matrix is a figurate number triangle: <http://mathworld.wolfram.com/FigurateNumberTriangle.html>

3 days ago

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Back to basics 16 - byte order
Covering some basic topics I haven't seen elsewhere on Cody. Switch the byte order of the input (i.e. if little-endian -> big...

3 days ago

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Find state names that end with the letter A
Given a list of US states, remove all the states that end with the letter A. Example: Input s1 = 'Alabama Montana Nebras...

3 days 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...

3 days ago

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Make a simplified barcode
Given an integer to encode, make a barcode using the following encoding scheme: * The bar code is made from the binary versio...

3 days ago