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# xiao chen

Last seen: 6 months ago Active since 2017

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Pattern matching
Given a matrix, m-by-n, find all the rows that have the same "increase, decrease, or stay same" pattern going across the columns...

6 months 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...

6 months ago

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Elapsed Time
Given two date strings d1 and d2 of the form yyyy/mm/dd HH:MM:SS (assume hours HH is in 24 hour mode), determine how much time, ...

6 months ago

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The Goldbach Conjecture, Part 2
The <http://en.wikipedia.org/wiki/Goldbach's_conjecture Goldbach conjecture> asserts that every even integer greater than 2 can ...

6 months 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...

6 months ago

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

6 months 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...

6 months 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...

6 months 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 ...

6 months ago

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It dseon't mettar waht oedrr the lrettes in a wrod are.
An internet meme from 2003 (read more here) asserted that readers are relatively insensitive to letter order in words, so long a...

6 months 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 between two...

7 months 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...

7 months ago

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

7 months 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...

7 months ago

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Find relatively common elements in matrix rows
You want to find all elements that exist in greater than 50% of the rows in the matrix. For example, given A = 1 2 3 5 ...

7 months 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...

7 months 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...

7 months 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...

7 months ago

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Extract Built In Functions and Toolbox Functions from String or Function Handle
Find the Built-In functions and Toolbox functions in either a string or a function handle. Generate a string of alphabetized ...

7 months ago

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Count letters occurence in text, specific to words with a given length.
Build a function with two input arguments: a string and a word length (number of letters), that outputs a vector of counts of th...

7 months 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 ...

7 months ago

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letter yes yes & letter no no
Split a string into two strings, wherein the first string has all alphabetic letters and the second string has all the remaining...

7 months ago

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QWERTY Shift Code Decoder
Decode a string encoded using the QWERTY shift code. QWERTY shift code is where the message was touch typed but with an offse...

7 months ago

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QWERTY Shift Encoder
Encode a string using the QWERTY shift code. This code is where you touch type but are offset by one character to the right. ...

7 months ago

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QWERTY coordinates
Given a lowercase letter or a digit as input, return the row where that letter appears on a standard U.S. QWERTY keyboard and it...

7 months 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 ...

7 months ago

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Word Distance - Sum
Let's suppose that the distance of a word can be calculated by summing the differences between its letters, having assigned the ...

7 months ago

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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:/...

7 months ago

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Project Euler: Problem 9, Pythagorean numbers
A Pythagorean triplet is a set of three natural numbers, a b c, for which, a^2 + b^2 = c^2 For example, 3^2 + 4^2 =...

7 months ago

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Project Euler: Problem 8, Find largest product in a large string of numbers
Find the greatest product of five consecutive digits in an n-digit number. 73167176531330624919225119674426574742355349194934...

7 months ago