# Hoang The Duong

Last seen: nästan 3 år ago Active since 2021

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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 ...

nästan 3 år ago

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Mersenne Primes vs. All Primes
A Mersenne prime (M) is a prime number of the form M = 2^p - 1, where p is another prime number. <https://www.mathworks.com/matl...

nästan 3 år ago

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Get all prime factors
List the prime factors for the input number, in decreasing order. List each factor. If the prime factor occurs twice, list it as...

nästan 3 år ago

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Factorize THIS, buddy
List the prime factors for the input number, in decreasing order. List each factor only once, even if the factorization includes...

nästan 3 år ago

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Generalised Hamming Number
Inspired by Project Euler n°204 and Problem 1308 by James A generalised Hamming number of type n, has no prime factor larger ...

nästan 3 år ago

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Numbers with prime factors 2, 3 and 5.
Make a function which takes one positive integer n and returns a matrix with the numbers of the form (2^i)*(3^j)*(5^k) which are...

nästan 3 år ago

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Find vampire numbers
A <http://en.wikipedia.org/wiki/Vampire_number vampire number> is a number v that is the product of two numbers x and y such th...

nästan 3 år ago

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Proper Factors
Generate the proper factors of input integer x and return them in ascending order. For more information on proper factors, refer...

nästan 3 år ago

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Multiples of a Number in a Given Range
Given an integer factor _f_ and a range defined by _xlow_ and _xhigh_ inclusive, return a vector of the multiples of _f_ that fa...

nästan 3 år ago

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Smith numbers
Return true if the input is a Smith number in base ten. Otherwise, return false. Read about Smith numbers at <http://en.wikipedi...

nästan 3 år 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...

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Primes Faster for Large N
This Challenge is to improve the "primes" function for speed. This may be accomplished by fixing memory usage. The Matlab fun...

nästan 3 år ago

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Circular Primes (based on Project Euler, problem 35)
The number, 197, is called a circular prime because all rotations of the digits: 197, 971, and 719, are themselves prime. The...

nästan 3 år 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]; ...

nästan 3 år ago

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Make a vector of prime numbers
Input(n) - length of vector with prime numbers Output(v) - vector of prime numbers Example: * n=1; v=2 * n=3; v=[2 3 5...

nästan 3 år 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...

nästan 3 år ago

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Mersenne Primes
A Mersenne prime is a prime number of the form M = 2^p - 1, where p is another prime number. For example, 31 is a Mersenne prim...

nästan 3 år 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...

nästan 3 år 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...

nästan 3 år ago

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Stuff the Board
You have a stack of tiles to put onto an array-like playing board. Each tile has a number (always an integer), and the board var...

nästan 3 år ago

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Rotate and display numbered tile
Imagine a square tile with four numbers on it, one on each edge. We will call these edges north, east, south, and west. If th...

nästan 3 år ago

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Find best domino orientation
Given a list of pairs, find the orientation they should be placed in a line, such that the sum of the absolute values of the dif...

nästan 3 år ago

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Choose the best fitting dominoes
You will be given a cell array of nx2 matrices. Choose one row from each matrix. These are the ordered pairs that will be plac...

nästan 3 år ago

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Find best placement for ordered dominoes (harder)
Given a list of ordered pairs, find the order they should be placed in a line, such that the sum of the absolute values of the d...

nästan 3 år ago

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Find perfect placement of non-rotating dominoes (easier)
Given a list of ordered pairs, find the order they should be placed in a line, such that the sum of the absolute values of the d...

nästan 3 år ago

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Scoring for oriented dominoes
Given a list of ordered pairs, and the order they should be placed in a line, find the sum of the absolute values of the differe...

nästan 3 år ago

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Can we make a triangle?
Given three positive number, check whether a triangle can be made with these sides length or not. remember that in a triangle su...

nästan 3 år 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 ...

nästan 3 år 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...

nästan 3 år 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...

nästan 3 år ago