Solved

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 ...

4 years ago

Solved

Encode Roman Numerals
Create a function taking a non-negative integer as its parameter and returning a string containing the Roman Numeral representat...

4 years ago

Solved

Roman numbers: how old is that building?
The front of old buildings sometimes show the year when they were built in roman numbers. These number are rather confusing and ...

4 years ago

Solved

Find the logic
There exists one logic in between input and output. Find it (easy math). Example 1: x=13 then y=339; Example 2: x=26...

4 years ago

Solved

Bit calculation
Give me the count of numbers from 1 to n having their last two bits as 0. For example function y = ret_count(4) y = x...

4 years ago

Solved

Compute the sum of reciprocals of quadratics
Write a function to compute the following sum: See also Cody Problem 46000.

4 years ago

Solved

Rock Paper Scissors Lizard Spock

4 years ago

Solved

Pick the die most likely to win
After discussing Rock, Paper, Scissors, Lizard, Spock in The Simpsons and their Mathematical Secrets, Simon Singh writes that in...

4 years ago

Solved

Matrix convolution
A certain convolution step involves an elementwise multipication between two 3x3 matrices and taking the resulting sum of the el...

4 years ago

Solved

All flights lead to Idaho Falls
Using spherical trigonometry and great circle paths, determine the distance (in kilometers) and the initial flight heading (from...

4 years ago

Solved

Compute the effective conductivity of a heterogeneous aquifer
Slow flow through soil or another porous medium follows Darcy’s law, which relates the flow of water to the gradient in piezome...

4 years ago

Solved

Compute a sum involving the totient over divisors of a number
Write a function to compute the following sum: where is the totient function. The sum is computed over the divisors of (inc...

4 years ago

Solved

Nuclear Binding Energy
Compute the approximate nuclear binding energy in MeV using the least-squares fit of the semi-emirical mass formula. Round to th...

4 years ago

Solved

Count numbers whose reciprocals' decimal expansions terminate

4 years ago

Solved

List Proth primes

4 years ago

Solved

Median computation (★★★)
See easy edition of this problem. However, now you must compute the median of any real-valued vector without using the in-built...

4 years ago

Solved

Approximate functions 2 (★★★★)

4 years ago

Solved

Eliminate redundant numbers in text
Occasionally someone might write text such as Briefly explain one (1) common problem that can result from the constant use of ...

4 years ago

Solved

Identify Ruth-Aaron numbers
After Hank Aaron hit his 715th home run and passed Babe Ruth’s total of 714, Carl Pomerance noticed that the union of the prime ...

4 years ago

Solved

Uranium–Lead Dating

4 years ago

Solved

Solve an ODE: equation C
Write a function to solve the following ordinary differential equation: with and . The parameter is a constant. The functi...

4 years ago

Solved

Count unique orderings of vertices of a polygon
Cody Problem 2671 asks us to determine whether four points can be the corners of a rectangle. The points are not necessarily inp...

4 years ago

Solved

Compute a sum of Ramanujan
Srinivasa Ramanujan defined the following function: Write a function to compute for various values of . See also Cody Proble...

4 years ago

Solved

Compute the harmonic numbers
The nth <https://mathworld.wolfram.com/HarmonicNumber.html harmonic number> is defined as the sum of the reciprocals of the inte...

4 years ago

Solved

Find the smallest integer m such that n divides m!
Write a function that takes an integer and finds the smallest integer whose factorial is divisible by . For example, if , then...

4 years ago

Solved

Reverse Boggle
*Description* In the classic Parker Brothers game <http://en.wikipedia.org/wiki/Boggle Boggle>, players find words from a 4x4...

4 years ago

Solved

Determine when snow started
R.P. Agnew posed the following problem: It starts snowing in the morning and continues steadily throughout the day. A snowplow t...

4 years ago

Solved

Code breaker, Part II: Operation Orthos
You have been tasked with decoding several batches of coded messages that have been intercepted. Based on previous intellig...

4 years ago

Solved

Code breaker, Part I: Operation Phoenix
You have been tasked with decoding a set of coded messages that have been intercepted. Based on previous intelligence that ...

4 years ago

Solved

Implement a ROT13 cipher
Replace each character in string s1 with the character that is shifted 13 positions from it (wrap back to the beginning if neces...

4 years ago