Solved

Solve an equation involving primes and fractions
Write a function to find pairs of primes and satisfying the equation where is an integer. The function should take a numbe...

1 year ago

Solved

List odd twin composites
Twin primes, or prime numbers that differ by 2 (e.g., 17 and 19, 59 and 61, or 191 and 193), are the subject of several Cody pro...

1 year ago

Solved

List the Beatriz numbers
Write a function to find integers less than or equal to an input value that solve the equation . The function gives the sum o...

1 year ago

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List the Euclid numbers
Euclid proved that the number of primes is infinite with the following argument. Suppose the primes form a finite set , , . Comp...

1 year ago

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Create Combination
Motivation: In many problems, we need to create combinations with the function nchoosek. In some cases, however, choices are lim...

1 year ago

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Usage of java.math : N Choose K with unlimited precision
Calculate the binomial coefficient nchoosek with full accuracy. This challenge may use the wonderful word of java.math that allo...

1 year ago

Solved

Get ranking of a combination looking for speed.
I have the numbers pulled without replacement from the set [1 2 3 4 5 6 7 8 9 10 11 12 13]; They are then ordered from least to...

1 year ago

Solved

Get ranking of a combination
I have the numbers pulled without replacement from the set [1 2 3 4 5 6 7 8 9 10 11 12 13]; They are then ordered from least to ...

1 year ago

Solved

Put m balls into n boxes (again)
According to Cody Problem 1516, if I put 3 balls into 2 boxes then 1 1 1 1 1 2 1 2 2 ...

1 year ago

Solved

Put m balls into n boxes
Can you find all the cases where, if I put 3 balls into 2 boxes the case is 1 1 1 1 1 2 1 ...

1 year ago

Solved

Numbered lottery balls into cells
You are running a lottery, and have a number of different balls numbered 1 to N. Your job is to figure out how many different w...

1 year ago

Solved

A (wrong) place for everything, and everything in its (wrong) place
You have an equal number of cups and balls, each labelled from one to N. You randomly place one ball in each cup. Determine th...

1 year ago

Solved

Possible Outcomes of American Roulette
The payout for American roulette can be calculated by: payout = (38/n)-1 where n is the number of squares the bet covers. ...

1 year ago

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NCHOOSEK - Time Optimization
Input V —— Set of all choices, a vector of N, 1 < N < 100 K —— Number of selected choices, a scalar, 0 <= K <= N Output C ——...

1 year ago

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Combinations without using nchoosek
You have to generate a matrix with all possible combinations of n elements *taken 2* at a time, *without using nchoosek(1:n,2)* ...

1 year ago

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Which permutation is it?
Let write some permutations of positive integers. 1: 1 2 3 4 5 6 ... 2: 2 1 3 4 ... 3: 1 3 2 4 ....

1 year ago

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N-th permutation.
Let write some permutations of positive integers. 1: 1 2 3 4 5 6 ... 2: 2 1 3 4 ... 3: 1 3 2 4 ... ...

1 year ago

Solved

Diophantine Equations (Inspired by Project Euler, problem 66)
Consider the quadratic Diophantine equation of the form: x^2 – Dy^2 = 1 When D=13, the minimal solution in x is 649^2 – 13...

1 year ago

Solved

High Precision Square Root (Inspired by Project Euler 80)
Given a positive integer n which is not a perfect square, write a MATLAB script that will calculate the square root of n truncat...

1 year ago

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Decrypt the cypher using XOR encryption (for beginners)
Inspired by Project Euler n°59 Each character on a computer is assigned a unique code and the preferred standard is ASCII (...

1 year ago

Solved

I've got the power! (Inspired by Project Euler problem 29)
Consider all integer combinations of a^b and b^a for the integer values 2 ≤ a ≤ 4 and 2 ≤ b ≤ 5: 2^2=4, 2^3=8, 2^4=16,...

1 year ago

Solved

Repopulate the City
For any population p of positive integers between pmin and pmax, we can calculate histogram count n for a list of evenly dividin...

1 year ago

Solved

Compute the Lagarias Riemann Hypothesis sequence
Write a function that takes an input number and produces a sequence (i.e., all values up to and including the th value) compute...

2 years ago

Solved

Compute the unitary totient of a number
The totient function , the subject of Cody Problems 656 and 50182, gives the number of integers smaller than that are relativel...

2 years ago

Solved

List the nth term of Rozhenko’s inventory sequence
Consider a sequence constructed by repeated inventories. A new inventory begins each time a zero is encountered. The first few i...

2 years ago

Solved

Count estrangements
Recently I made a puzzle for my wife that included a cryptogram, which involves an arrangement of the letters A through Z. I use...

2 years ago

Solved

Trap a knight
Consider a knight on an infinite chessboard labeled with numbers spiraling outward. A knight starting on the square labeled 1 ca...

2 years ago

Solved

Compute the Tetris sequence
In the Tetris sequence, which starts with a 1, the next term is the smallest positive integer not already in the sequence that h...

2 years ago

Solved

Flip the parity of digits in a decimal expansion
The number 349 has the decimal expansion . If we change the even digits from positive to negative, then the number becomes 269 (...

2 years ago

Solved

Compute the largest number with a given integer complexity
Cody Problems 42831 and 42834 ask us to compute integer complexity, the smallest number of 1s needed to construct a number with ...

2 years ago