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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...

14 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...

14 years ago | 17 | 352 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...

14 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...

14 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...

14 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 , ...

14 years ago

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

14 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...

14 years ago

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

14 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

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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

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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

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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

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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

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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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