Ismael Valdes

Last seen: 3 years ago | Active since 2021

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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 + ...

3 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...

3 years ago

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Make a Palindrome Number
Some numbers like 323 are palindromes. Other numbers like 124 are not. But look what happens when we add that number to a revers...

3 years ago

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Sums with Excluded Digits
Add all the integers from 1 to n in which the digit m does not appear. m will always be a single digit integer from 0 to 9. no...

3 years ago

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Tic Tac Toe FTW
Given a tic tac toe board: * 1 represents X * 0 represents empty. * -1 represents O It is X's move. If there is an imme...

3 years ago

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

3 years ago

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Return the largest number that is adjacent to a zero
This example comes from Steve Eddins' blog: <http://blogs.mathworks.com/steve/2009/05/27/learning-lessons-from-a-one-liner/ Lear...

3 years ago

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Nearest Numbers
Given a row vector of numbers, find the indices of the two nearest numbers. Examples: [index1 index2] = nearestNumbers([2 5 3...

3 years ago

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Which values occur exactly three times?
Return a list of all values (sorted smallest to largest) that appear exactly three times in the input vector x. So if x = [1 2...

3 years 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...

3 years 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...

3 years ago

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Remove any row in which a NaN appears
Given the matrix A, return B in which all the rows that have one or more <http://www.mathworks.com/help/techdoc/ref/nan.html NaN...

3 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...

3 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...

3 years ago

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Fibonacci sequence
Calculate the nth Fibonacci number. Given n, return f where f = fib(n) and f(1) = 1, f(2) = 1, f(3) = 2, ... Examples: Inpu...

3 years ago

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Determine whether a vector is monotonically increasing
Return true if the elements of the input vector increase monotonically (i.e. each element is larger than the previous). Return f...

3 years ago

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Return a list sorted by number of occurrences
Given a vector x, return a vector y of the unique values in x sorted by the number of occurrences in x. Ties are resolved by a ...

3 years ago

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Find all elements less than 0 or greater than 10 and replace them with NaN
Given an input vector x, find all elements of x less than 0 or greater than 10 and replace them with NaN. Example: Input ...

3 years ago

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Determine if input is odd
Given the input n, return true if n is odd or false if n is even.

3 years ago

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Generate n equally spaced "intervals" between -x and x (★)
Given n and x, return a list of numbers (in ascending order) that divides the interval [-x x] into n equal-length intervals. ...

3 years ago

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Create a vector of the first n odd numbers (★)
If n = 10, your program should return a vector y, where y = [1 3 5 7 9 11 13 15 17 19].

3 years ago

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Remove the row average (★★★)
(copy of Prob. 963) Given a 2-d matrix, remove the row average from each row. Your solution MUST be vectorized. The solut...

3 years ago

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Doubling elements in a vector (★★)
(copy of prob. 1024) Given the vector A, return B in which all numbers in A are doubling. So for: A = [ 1 5 8 ] t...

3 years ago

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Create times-tables (★★★)
(copy of prob 33) At one time or another, we all had to memorize boring times tables. 5 times 5 is 25. 5 times 6 is 30. 12 ti...

3 years ago

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Create logarithmically spaced values (★)
Given three numbers a,b,n with b>a, create a vector y with n logarithmic spaced values between 10^a and 10^b. Thus, if a = -2, ...

3 years ago

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Element-wise vector product (★)
Given two vectors x and y, compute their element-wise product z. Thus, if x = [1 3 5] and y = [0.5 -1 2], then z = [1*0.5...

3 years ago

Solved

Vector raised to a power, element-wise (★)
Given a vector A and a number x, raise each element of the vector to the power of x. Thus, if A = [2 5 7 1] and x = 0.5, then ...

3 years ago

Solved

Generate a vector which contains a pyramid pattern (★★★★)
Generate a vector that contains terms that follows a pyramid pattern up to the nth row: 1 2 2 3 3 3 4 4 4 4 ...

3 years ago

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Create a vector with n repeated values of a number x (★★)
If x=3 and n=7 then the vector y would be y=[3 3 3 3 3 3 3]

3 years ago

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Average of corner elements of a matrix (★★)
(copy of prob 2235) Calculate the average of corner elements of a matrix. e.g. x=[1 2 3; 4 5 6; 7 8 9;] avg = (1+3+7+9)...

3 years ago