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# Jan

### Research institute

52 total contributions since 2014

Researcher
Professional Interests: Algorithms

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Solved

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...

meer dan 5 jaar 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...

meer dan 5 jaar 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 ...

meer dan 5 jaar ago

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Find the biggest empty box
You are given a matrix that contains only ones and zeros. Think of the ones as columns in an otherwise empty floor plan. You wan...

meer dan 5 jaar 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 ...

meer dan 5 jaar 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 ...

meer dan 5 jaar 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...

meer dan 5 jaar 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 ...

meer dan 5 jaar 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...

meer dan 5 jaar ago

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Elapsed time is -0.005204 seconds.
Write a function that takes less than zero seconds to execute, as measured using tic and toc. For repeatability, the test case p...

meer dan 5 jaar 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...

meer dan 5 jaar ago

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Detect a number and replace with two NaN's
Write code which replaces the number 1 with two NaNs. Example X = [ 1 2 NaN 4 1 3 7 NaN 1 4 NaN 2] ...

meer dan 5 jaar ago

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Who Has the Most Change?
You have a matrix for which each row is a person and the columns represent the number of quarters, nickels, dimes, and pennies t...

meer dan 5 jaar ago

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Back and Forth Rows
Given a number n, create an n-by-n matrix in which the integers from 1 to n^2 wind back and forth along the rows as shown in the...

meer dan 5 jaar ago

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Remove all the consonants
Remove all the consonants in the given phrase. Example: Input s1 = 'Jack and Jill went up the hill'; Output s2 is 'a ...

meer dan 5 jaar ago

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Is my wife right? Now with even more wrong husband
Again, as in "Is my wife right?" ( <http://www.mathworks.com/matlabcentral/cody/problems/149-is-my-wife-right> ), answer 'yes' r...

meer dan 5 jaar ago

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Find the longest sequence of 1's in a binary sequence.
Given a string such as s = '011110010000000100010111' find the length of the longest string of consecutive 1's. In this examp...

meer dan 5 jaar ago

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Solve the Sudoku Row
*Description* A simple yet tedious task occurs near the end of most Sudoku-solving algorithms, computerized or manual. The ta...

meer dan 5 jaar 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...

meer dan 5 jaar ago

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*Description* The Soroban is the name of the modern Japanese abacus. Information on reading a Soroban can be found <http://we...

meer dan 5 jaar ago

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Free passes for everyone!
_Simply return the name of the coolest numerical computation software ever_ *Extra reward* (get a _freepass_): As an addit...

meer dan 5 jaar ago

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Function Iterator
Given a handle fh to a function which takes a scalar input and returns a scalar output and an integer n >= 1, return a handle f...

meer dan 5 jaar ago

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

meer dan 5 jaar ago

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The Hitchhiker's Guide to MATLAB
Output logical "true" if the input is the answer to life, the universe and everything. Otherwise, output logical "false".

meer dan 5 jaar ago

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Sort a list of complex numbers based on far they are from the origin.
Given a list of complex numbers z, return a list zSorted such that the numbers that are farthest from the origin (0+0i) appear f...

meer dan 5 jaar ago

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Summing digits
Given n, find the sum of the digits that make up 2^n. Example: Input n = 7 Output b = 11 since 2^7 = 128, and 1 + ...

meer dan 5 jaar ago

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Check if sorted
Check if sorted. Example: Input x = [1 2 0] Output y is 0

meer dan 5 jaar 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...

meer dan 5 jaar ago

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Find the numeric mean of the prime numbers in a matrix.
There will always be at least one prime in the matrix. Example: Input in = [ 8 3 5 9 ] Output out is 4...

meer dan 5 jaar ago

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Weighted average
Given two lists of numbers, determine the weighted average. Example [1 2 3] and [10 15 20] should result in 33.333...

meer dan 5 jaar ago