Xinyi

Last seen: 2 years ago | Active since 2024

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Doubling elements in a vector
Given the vector A, return B in which all numbers in A are doubling. So for: A = [ 1 5 8 ] then B = [ 1 1 5 ...

2 years ago

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Magic is simple (for beginners)
Determine for a magic square of order n, the magic sum m. For example m=15 for a magic square of order 3.

2 years ago

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Return the first and last characters of a character array
Return the first and last character of a string, concatenated together. If there is only one character in the string, the functi...

2 years ago

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Create times-tables
At one time or another, we all had to memorize boring times tables. 5 times 5 is 25. 5 times 6 is 30. 12 times 12 is way more th...

2 years ago

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Finding Perfect Squares
Given a vector of numbers, return true if one of the numbers is a square of one of the numbers. Otherwise return false. Example...

2 years ago

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Test if a Number is a Palindrome without using any String Operations
*Description* Given an integer _X_, determine if it is a palindrome number. That is, _X_ is equal to the _X_ with the digits ...

2 years ago

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Increment a number, given its digits
Take as input an array of digits (e.g. x = [1 2 3]) and output an array of digits that is that number "incremented" properly, (i...

2 years ago

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Split bread like the Pharaohs - Egyptian fractions and greedy algorithm
How would you split 5 loaves of bread among 8 people in all fairness? Get a hint from the Pharaohs. 5/8 = 4/8 + 1/8 , i.e. each ...

2 years ago

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7 segment LED display
Given a whole number, output how many segments would be lit up to display it on a 7 segment LED display (see Wikipedia: http://e...

2 years ago

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Convert Roman to Arabic Numerals
Based upon what I see on tv and at the movies, the use of Roman numerals indicates something is important or sophisticated (e.g....

2 years ago

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Number of 1s in the Binary Representation of a Number
*Description* Return the number of 1s in the (unsigned integer) binary representation of a number. This function should be ab...

2 years ago

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Sum of series VI
What is the sum of the following sequence: Σk⋅k! for k=1...n for different n?

2 years ago

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Sum of series IX
What is the sum of the following sequence: Σ 1/k! for k=1...n for different n?

2 years ago

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Sum of series VIII

2 years ago

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Sum of series
a(n) = n^2 - (n-1)^2 find the summation of the series upto n i.e. a(1)+a(2)+...+a(n)

2 years ago

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Sum of series IV
What is the sum of the following sequence: Σ(-1)^(k+1) (2k-1)^2 for k=1...n for different n?

2 years ago

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Sum of series V
What is the sum of the following sequence: Σk(k+1) for k=1...n for different n?

2 years ago

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Sum of series III
What is the sum of the following sequence: Σ(2k-1)^3 for k=1...n for different n?

2 years ago

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Sum of series II
What is the sum of the following sequence: Σ(2k-1)^2 for k=1...n for different n?

2 years ago

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Sum of series I
What is the sum of the following sequence: Σ(2k-1) for k=1...n for different n?

2 years ago

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Sum of series VII
What is the sum of the following sequence: Σ(km^k)/(k+m)! for k=1...n for different n and m?

2 years ago

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Split Even Number Into Two Primes
Given an even whole number n (> 2), return a 2-element vector of primes, p, such that p(1) + p(2) = n. The elements of p should ...

2 years ago

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Determine if Input is Oddish or Evenish (Odd/Even Sum of Digits)
Given a positive integer n, determine whether n is "oddish" or "evenish" - that is, whether the sum of the digits of n is odd or...

2 years 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...

2 years 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 years 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 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...

2 years 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...

2 years 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 = 9 + 16 ...

2 years ago

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First N Perfect Squares
*Description* Return the first N perfect squares *Example* input = 4; output = [ 1 4 9 16 ];

2 years ago