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Counting Sequence
Given a vector x, find the "counting sequence" y. A counting sequence is formed by "counting" the entries in a given sequence...

4 years ago

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Largest Twin Primes
<http://en.wikipedia.org/wiki/Twin_prime Twin primes> are primes p1, p2 = p1 + 2 such that both p1 and p2 are prime numbers. Giv...

4 years ago

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Find the next prime number
Find the next prime number or numbers for given n. For example: n = 1; out = 2; or n = [5 7]; out = [7 11]; ...

4 years ago

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Find nearest prime number less than input number
Find nearest prime number less than input number. For example: if the input number is 125, then the nearest prime number whi...

4 years ago

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Sophie Germain prime
In number theory, a prime number p is a *Sophie Germain prime* if 2p + 1 is also prime. For example, 23 is a Sophie Germain prim...

4 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...

4 years 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:/...

4 years ago

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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 ...

4 years ago

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"mirror" matrix
Create n x 2n "mirror" matrix of this type: Examples For n = 2 m = [ 1 2 2 1 1 2 2 1 ] For n = 3 m = ...

4 years ago

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Create a Multiplication table matrix...
Create a product table in this format: P = [ 1 2 3 4 5; 2 4 6 8 10; 3 6 9 12 15; 4 8 12 1...

4 years 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 <http://en.wikipedia.org/wiki/Keyboa...

4 years ago

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Maximum running product for a string of numbers
Given a string s representing a list of numbers, find the five consecutive numbers that multiply to form the largest number. Spe...

4 years 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 ...

4 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...

4 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...

4 years ago

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Replace NaNs with the number that appears to its left in the row.
Replace NaNs with the number that appears to its left in the row. If there are more than one consecutive NaNs, they should all ...

4 years ago

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Remove the vowels
Remove all the vowels in the given phrase. Example: Input s1 = 'Jack and Jill went up the hill' Output s2 is 'Jck nd Jll wn...

4 years ago

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Return the 3n+1 sequence for n
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...

4 years 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 + ...

4 years ago

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Making change
Given an amount of currency, return a vector of this form: [100 50 20 10 5 2 1 0.5 0.25 0.1 0.05 0.01] Example: Input a = ...

4 years 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...

4 years 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, ...

4 years ago

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Is the Point in a Triangle?
Check whether a point or multiple points is/are in a triangle with three corners Points = [x, y]; Triangle = [x1, y1; x...

4 years ago

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Find the sides of an isosceles triangle when given its area and height from its base to apex
Find the sides of an isosceles triangle when given its area and the height from its base to apex. For example, with A=12 and ...

4 years ago

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Height of a right-angled triangle
Given numbers a, b and c, find the height of the right angled triangle with sides a and b and hypotenuse c, for the base c. If a...

4 years ago

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Right Triangle Side Lengths (Inspired by Project Euler Problem 39)
If _p_ is the perimeter of a right angle triangle with integral length sides, { _a_, _b_, _c_ }, there are exactly three solutio...

4 years ago

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Find my daddy long leg (No 's')
Given the ratio of the two legs (longer / shorter), and the hypotenuse length, find the value of the bigger leg.

4 years ago

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Project Euler: Problem 3, Largest prime factor
The prime factors of 13195 are 5, 7, 13 and 29. What is the largest prime factor of the number being input, input might be ui...

4 years ago

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Project Euler: Problem 1, Multiples of 3 and 5
If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23...

4 years ago

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There are 10 types of people in the world
Those who know binary, and those who don't. The number 2015 is a palindrome in binary (11111011111 to be exact) Given a year...

4 years ago