Tuan

Last seen: 19 days ago | Active since 2025

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swap sign sum & multiply castles
It is an easy problem, if you know the answer. Given a square matrix of NxN ordinary numbers. Initially place N identical indi...

1 month 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...

1 month 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...

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Project Euler: Problem 7, Nth prime
By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13. What is the Nth prime numb...

1 month 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]; ...

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The Goldbach Conjecture
The Goldbach conjecture asserts that every even integer greater than 2 can be expressed as the sum of two primes. Given the eve...

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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...

1 month 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...

1 month 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...

1 month 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...

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

1 month 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...

1 month 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...

1 month 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...

1 month ago

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Pi Digit Probability
Assume that the next digit of pi constant is determined by the historical digit distribution. What is the probability of next di...

1 month ago

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Integer Sequence - II : New Fibonacci
Crack the following Integer Sequence. (Hints : It has been obtained from original Fibonacci Sequence and all the terms are also ...

1 month ago

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Fibonacci Decomposition
Every positive integer has a unique decomposition into nonconsecutive Fibonacci numbers f1+f2+ ... Given a positive integer n, r...

1 month ago

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Return fibonacci sequence do not use loop and condition
Calculate the nth Fibonacci number. Given n, return f where f = fib(n) and f(1) = 1, f(2) = 1, f(3) = 2, ... Examples: ...

1 month ago

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Return the Fibonacci Sequence
Write a code which returns the Fibonacci Sequence such that the largest value in the sequence is less than the input integer N. ...

2 months ago

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Find the next Fibonacci number
In the sequence of Fibonacci numbers, every number is the sum of the two preceding ones: 1, 1, 2, 3, 5, 8, 13, 21, 34, 55...

2 months ago

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Pi Estimate 1
Estimate Pi as described in the following link: <http://www.people.virginia.edu/~teh1m/cody/Pi_estimation1.pdf>

2 months ago

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How many Fibonacci numbers?
Find the number of unique Fibonacci numbers (don't count repeats) in a vector of positive integers. Example: x = [1 2 3 4...

2 months 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...

2 months 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...

2 months ago

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Project Euler: Problem 2, Sum of even Fibonacci
Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 te...

2 months ago

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Number of Even Elements in Fibonacci Sequence
Find how many even Fibonacci numbers are available in the first d numbers. Consider the following first 14 numbers 1 1 2...

2 months ago

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Fibonacci-Sum of Squares
Given the Fibonacci sequence defined by the following recursive relation, * F(n) = F(n-1) + F(n-2) * where F(1) = 1 and F(1)...

2 months ago

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matrix zigzag
Unfold a 2-D matrix to a 1-D array in zig-zag order, e.g., for matrix [ 1 2 3 ; 4 5 6 ; 7 8 9 ] the resulting 1-...

2 months 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...

2 months ago