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Extract leading non-zero digit
<http://en.wikipedia.org/wiki/Benford%27s_law Benford's Law> states that the distribution of leading digits is not random. This...

2 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...

2 years ago

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Which doors are open?
There are n doors in an alley. Initially they are all shut. You have been tasked to go down the alley n times, and open/shut the...

2 years ago

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Make a Palindrome Number
Some numbers like 323 are palindromes. Other numbers like 124 are not. But look what happens when we add that number to a revers...

2 years ago

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Trimming Spaces
Given a string, remove all leading and trailing spaces (where space is defined as ASCII 32). Input a = ' singular value deco...

2 years ago

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Reverse Run-Length Encoder
Given a "counting sequence" vector x, construct the original sequence y. A counting sequence is formed by "counting" the entrie...

2 years ago

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Find the alphabetic word product
If the input string s is a word like 'hello', then the output word product p is a number based on the correspondence a=1, b=2, ....

2 years ago

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Which values occur exactly three times?
Return a list of all values (sorted smallest to largest) that appear exactly three times in the input vector x. So if x = [1 2...

2 years ago

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Pascal's Triangle
Given an integer n >= 0, generate the length n+1 row vector representing the n-th row of <http://en.wikipedia.org/wiki/Pascals_t...

2 years ago

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Binary numbers
Given a positive, scalar integer n, create a (2^n)-by-n double-precision matrix containing the binary numbers from 0 through 2^n...

2 years ago

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Most nonzero elements in row
Given the matrix a, return the index r of the row with the most nonzero elements. Assume there will always be exactly one row th...

2 years ago

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Create times-tables
At one time or another, we all had to memorize boring times tables. 5 times 5 is 25. 5 times 6 is 30. 12 times 12 is way more th...

2 years ago

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Quote Doubler
Given a string s1, find all occurrences of the single quote character and replace them with two occurrences of the single quote ...

2 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 ...

2 years ago

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Nearest Numbers
Given a row vector of numbers, find the indices of the two nearest numbers. Examples: [index1 index2] = nearestNumbers([2 5 3...

2 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...

2 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 roots of the p...

2 years ago

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Find the two most distant points
Given a collection of points, return the indices of the rows that contain the two points most distant from one another. The inpu...

2 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...

2 years ago

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Find common elements in matrix rows
Given a matrix, find all elements that exist in every row. For example, given A = 1 2 3 5 9 2 5 9 3 2 5 9 ...

2 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...

2 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),...

2 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...

2 years ago

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Pangrams!
A pangram, or holoalphabetic sentence, is a sentence using every letter of the alphabet at least once. Example: Input s ...

2 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...

2 years ago

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Summing Digits within Text
Given a string with text and digits, add all the numbers together. Examples: Input str = '4 and 20 blackbirds baked in a...

2 years ago

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Word Counting and Indexing
You are given a list of strings, each being a list of words divided by spaces. Break the strings into words, then return a maste...

2 years ago

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Bullseye Matrix
Given n (always odd), return output a that has concentric rings of the numbers 1 through (n+1)/2 around the center point. Exampl...

2 years ago

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Alphabetize by last name
Given a list of names in a cell array, sort the list by the last name. So if list = {'Barney Google','Snuffy Smith','Dagwood ...

2 years ago

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Kaprekar Steps
6174 is the Kaprekar constant. All natural numbers less than 10,000 (except some with same digits) can be reduced to 6174 in the...

2 years ago

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