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How long is the longest prime diagonal?
Stanislaw Ulam once observed that if the counting numbers are <http://en.wikipedia.org/wiki/Ulam_spiral arranged in a spiral>, t...

13 years ago

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Find a subset that divides the vector into equal halves
Given a vector x, return the indices to elements that will sum to exactly half of the sum of all elements. Example: Inpu...

13 years ago

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Spot the outlier
All points except for one lie on a line. Which one is the outlier? Example: You are given a list of x-y pairs in a column ...

13 years ago

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Make a run-length companion vector
Given a vector x, return a vector r that indicates the run length of any value in x. Each element in r shows how many times the ...

13 years ago

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Flag largest magnitude swings as they occur
You have a phenomenon that produces strictly positive or negative results. delta = [1 -3 4 2 -1 6 -2 -7]; Marching thr...

13 years ago

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Given a window, how many subsets of a vector sum positive
Given a vector: [1 0 -1 3 2 -3 1] and a window of 2, A sliding window would find: 1 + 0 = 1 0 - 1 = -1 ...

13 years ago

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How many trades represent all the profit?
Given a list of results from trades made: [1 3 -4 2 -1 2 3] We can add them up to see this series of trades made a profit ...

13 years ago

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Implement simple rotation cypher
If given a letter from the set: [abc...xyz] and a shift, implement a shift cypher. Example: 'abc' with a shi...

13 years ago

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Remove all the words that end with "ain"
Given the string s1, return the string s2 with the target characters removed. For example, given s1 = 'the main event' your ...

13 years ago

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Knight's Tour Checker
Given a matrix a, determine whether or not a legal <http://en.wikipedia.org/wiki/Knight's_tour knight's tour> is present. The kn...

13 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...

13 years ago

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Calculate the Levenshtein distance between two strings
This problem description is lifted from <http://en.wikipedia.org/wiki/Levenshtein_distance>. The Levenshtein distance betwee...

13 years ago

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Get the area codes from a list of phone numbers
Given a string of text with phone numbers in it, return a unique'd cell array of strings that are the area codes. s = '508-647...

13 years ago

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Find state names that start with the letter N
Given a list of US states, remove all the states that start with the letter N. If s1 = 'Alabama Montana Nebraska Vermont Ne...

13 years ago

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Connect Four Win Checker
<http://en.wikipedia.org/wiki/Connect_Four Connect Four> is a game where you try to get four pieces in a row. For this problem, ...

13 years ago

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Counting in Finnish
Sort a vector of single digit whole numbers alphabetically by their name, in Finnish. See the Wikipedia page for <http://en.wik...

13 years ago

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It dseon't mettar waht oedrr the lrettes in a wrod are.
An internet meme from 2003 (read more <http://www.snopes.com/language/apocryph/cambridge.asp here>) asserted that readers are re...

13 years ago

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Indexed Probability Table
This question was inspired by a Stack Overflow question forwarded to me by Matt Simoneau. Given a vector x, make an indexed pro...

13 years ago

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Renaming a field in a structure array
MATLAB has a <http://www.mathworks.com/help/techdoc/ref/setfield.html setfield> and a <http://www.mathworks.com/help/techdoc/ref...

13 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. ...

13 years 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...

13 years ago

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Remove the small words from a list of words.
Your job is to tidy up a list of words that appear in a string. The words are separated by one or more spaces. Remove all words ...

13 years ago

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

13 years ago

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DNA N-Gram Distribution
Given a string s and a number n, find the most frequently occurring n-gram in the string, where the n-grams can begin at any poi...

13 years ago

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Implement a ROT13 cipher
Replace each character in string s1 with the character that is shifted 13 positions from it (wrap back to the beginning if neces...

13 years ago

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Clean the List of Names
Given a list of names in a cell array, remove any duplications that result from different capitalizations of the same string. So...

13 years ago

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De-dupe
Remove all the redundant elements in a vector, but keep the first occurrence of each value in its original location. So if a =...

13 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';

13 years ago

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Counting Money
Add the numbers given in the cell array of strings. The strings represent amounts of money using this notation: $99,999.99. E...

13 years ago

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Balanced number
Given a positive integer find whether it is a balanced number. For a balanced number the sum of first half of digits is equal to...

13 years ago