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Sum the entries of each column of a matrix which satisfy a logical condition.
Given a numeric matrix A and a logical array L of the same size as A, return a row vector S containing the columnwise sums of th...

13 years ago

Problem


Create logical matrix with a specific row and column sums
Given two numbers *|n|* and *|s|*, build an |n-by-n| logical matrix (of only zeros and ones), such that both the row sums and th...

13 years ago | 17 | 345 solvers

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Bang Bang in Bangalore
Imagine a strange language disorder, Bangolangosis, has developed among trigonometricians of <http://en.wikipedia.org/wiki/Banga...

13 years ago

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Blood test?
Assuming: the genetic makeup (genotype) of a child is coded as a pair with two components, combining half genotype of one parent...

13 years ago

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Use of regexp
* Given a string, containing several sentences, such as: * 'I played piano. John played football. Anita went home. Are you safe...

13 years ago

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Compress strings (not springs)
Please remove excess space, limit one space between others, and no space before punctuation marks. * For example, 'Trendy , ...

13 years ago

Solved


Vectorizing, too easy or too hard?
Please insert a . before any ^, * or / in the string. That's it!!

13 years ago

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letter yes yes & letter no no
Split a string into two strings, first string has all alphabetic letters, next string has all the rest, keep the order please, o...

13 years ago

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Least common multiple of many numbers
1:6 -> 60

13 years ago

Solved


Project Euler: Problem 10, Sum of Primes
The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. Find the sum of all the primes below the input, N. Thank you <http:/...

14 years ago

Solved


Project Euler: Problem 6, Natural numbers, squares and sums.
The sum of the squares of the first ten natural numbers is, 1^2 + 2^2 + ... + 10^2 = 385 The square of the sum of the first ...

14 years ago

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Solitaire Cipher
Implement the <http://en.wikipedia.org/wiki/Solitaire_(cipher) solitaire cipher>. Since this is from Wikipedia, I am capturin...

14 years ago

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Choose the best fitting dominoes
You will be given a cell array of nx2 matrices. Choose one row from each matrix. These are the ordered pairs that will be plac...

14 years ago

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Find best domino orientation
Given a list of pairs, find the orientation they should be placed in a line, such that the sum of the absolute values of the dif...

14 years ago

Solved


Rotate and display numbered tile
Imagine a square tile with four numbers on it, one on each edge. We will call these edges north, east, south, and west. If th...

14 years ago

Solved


Find best placement for ordered dominoes (harder)
Given a list of ordered pairs, find the order they should be placed in a line, such that the sum of the absolute values of the d...

14 years ago

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Longest Divisor Run
Given the vector a, find the longest run of consecutive numbers that can be evenly divided by the same number d where d > 1. ...

14 years ago

Solved


Mandelbrot Numbers
The <http://en.wikipedia.org/wiki/Mandelbrot_set Mandelbrot Set> is built around a simple iterative equation. z(1) = c z...

14 years ago

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Given two strings, find the maximum overlap
Given two strings s1 and s2, create a new string s3 which is as short as possible and contains both strings. If s1 = [1 2...

14 years ago

Solved


What is the next step in Conway's Life?
Given a matrix A that represents the state of <http://en.wikipedia.org/wiki/Conway's_Game_of_Life Conway's game of Life> at one ...

14 years ago

Solved


Kaprekar Steps
6174 is the <http://en.wikipedia.org/wiki/6174_%28number%29 Kaprekar constant>. All natural numbers less than 10,000 (except som...

14 years ago

Solved


Find the palindrome
Given the string a, find the longest palindromic sub-string b. So when a = 'xkayakyy'; you should return b = 'kayak';

14 years ago

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Encode Roman Numerals
Create a function taking a non-negative integer as its parameter and returning a string containing the Roman Numeral representat...

14 years ago

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Interpolator
You have a two vectors, a and b. They are monotonic and the same length. Given a value, va, where va is between a(1) and a(end...

14 years ago

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Find the peak 3n+1 sequence value
A Collatz sequence is the sequence where, for a given number n, the next number in the sequence is either n/2 if the number is e...

14 years ago

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Remove the polynomials that have positive real elements of their roots.
The characteristic equation for a dynamic system is a polynomial whose roots indicate its behavior. If any of the <http://www.ma...

14 years ago

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Read a column of numbers and interpolate missing data
Given an input cell array of strings s, pick out the second column and turn it into a row vector of data. Missing data will be i...

14 years ago

Solved


Change a specific color in an image
The ability to change colors can be a useful tool in image processing. Given an m x n x 3 array (much like CData in images), fin...

14 years ago

Solved


N-Dimensional Array Slice
Given an N-dimensional array, _A_, an index, _I_, and a dimension, _d_, return the _I_ th elements of _A_ in the _d_ dimension. ...

14 years ago

Solved


Mersenne Primes
A Mersenne prime is a prime number of the form M = 2^p - 1, where p is another prime number. For example, 31 is a Mersenne prim...

14 years ago

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