An arithmetico-geometric sequence is the elementwise product of an arithmetic sequence and a geometric sequence. For example, 1 -4 6 -32 is the product of the arithmetic sequence 1 2 3 4 and the geometric sequence 1 -2 4 -8. The nth term of an arithmetico-geometric sequence can be expressed as $...

Least Weighted Path Let A be an m by n rectangular matrix of positive integers. We are interested in paths from the upper-left cell of A to the lower right cell; where each successive cell of the path is horizontally or vertically adjacent to the previous cell. Given any such path, we can take ...

Some people are very good code golfers but for their own reasons do not want to join PPCG. Is it acceptable to post their solutions as answers to challenges? If at all acceptable, I would personally do so only as Community Wiki and only with full reference to the original author and their code. ...

ASCII art H trees An H tree is a fractal tree structure that starts with a line. In each iteration, T branches are added to all endpoints. In this challenge, you have to create an ASCII representation of every second H tree level. The first level simply contains three hyphen-minus characters: ...

Randomness is fun. Challenges with no point are fun. Write a function that, given integer input n, will output a set (unordered, unique) of exactly n random integers between 1 and n^2 (inclusive) such that the sum of all integers is equal to n^2 Randomness does not have to be uniform, provided ...

Given an array A of integers, there exists at least one positive integer p such that A[i] == A[j] for all i and j for which i % p == j % p == 0. Find the smallest p. Examples: Input array: [1, _, 1_, 1, _, 1, _, 1]. Output: 2 Input array: [1, _, _, 1, _, _, 1, _, _]. Output: 3. Input array: [1...

Given integer n, calculate a set of n random unique integers in range 1..n^2 (inclusive) such that the sum of the set is equal to n^2 Random, in this case, means uniformly random between valid outputs. Each valid output for a given n must have a uniform chance of being generated. For example, n...

The question is in the title. I'm interested in submissions that terminate with probability 1 but have unbounded worst case running times. This is related to the question Do programs have to terminate?, but that question is specifically about submissions that definitely do not terminate. For ...

The Hungry Moose code-golf Inspiration. Moose face harsh conditions during the winter. According to one source: Their winter foods are lower quality than what they eat in summer and provides less energy, consequently, they need to eat more of it. During harsh winters, having both extreme c...

Find the best K year period to have invested A stock index is a way of measuring the overall performance of the stock prices of a group of companies (which may change from time to time). An example from the US is called the S&P 500. An index fund is an investment that grow at the same rate as th...