An anagram chain quine permutations code-golf Your challenge is to create a program, P_0, that outputs P_1, that outputs P_2, that outputs... P_n, which finally outputs P_0. Every program in that chain has to be a permutation of every other program, and every program has to be distinct. For exa...

Secret Message-Part 1, Elements code-golf string encryption You and your friend want to send each other secret messages. However, because you are conspiracy theorists and think that the government has a quantum computer that can crack any standard encryption. Therefore, you are inventing one o...

You are an employee at the hip new grocery store Half Foods, and it's the day before Thanksgiving Christmas Easter. Since the store will be packed with customers rushing to get their foodstuffs, the store needs a traffic manager to send everyone to the appropriate lines. Being lazy, you'd like to...

Given a set of nine single (not necessarily distinct) digits, (say 0, 0, 1, 3, 4, 6, 7, 8, 9),using each of the digits only once, it is possible to form several distinct times in a 12-hour time format (HH:MM:SS), For example: 10:36:40 or 01:39:46. The objective is to find the maximum possible va...

A curve is a set of points on a square grid such that each point has exactly two neighbors in the four-neighbor neighborhood and the points form a single connected component. That is, the graph induced by the points on a grid graph is isomorphic to a single cycle. "Induced" means that two points ...

This challenge is pretty simple: Your task is to draw a schematic of a (simplified) memory array. You will be given two (positive) integers n,m and the task is to draw the n:2^n decoder connected to the memory array with d data lines. The addressing will be in the order of gray codes, to check i...

For this challenge you need to make a given word by concatenating "pieces" (a.k.a contiguous substrings) from other words. Given a word and a list of words as input, output the fewest number of pieces needed to create the first word. Rules Words consist of characters in the ASCII range 33 to ...

Given a single positive odd integer as input, return a converging zigzag as a list of strings, list of lists of characters, or newline-separated string, in this form: # # # # # # # # # # # You can replace # with any consistent non-whitespace character. Trailing whitespac...

You will be given a String consisting of printable ASCII (without newlines). Your task is to build a nice Stairway for my Castle. How to build a nice Stairway? First off, you should get all the rotations of the String. For example, the String abcd has the following rotations: abcd, bcda, cdab,...

Given a string containing only letters (case-insensitive), split it into words of uniformly random lengths, using the distribution below, with the exception of the last word, which can be of any valid length (1-10). Your output is these words, as a space-separated string ("test te tests"), an arr...

Is it cat-urday? Caturday is one of the oldest memes out there. For this challenge you need to write a program that outputs the input, but only on Saturday. The catch: You can acquire the date via UNIX timestamp, or as a formatted date string (local or UTC). However, you can not: use day of...

Identify Topology code-golfdecision-problemmathtopology Given a set T of subsets of a finite set S={1,2,3,...,n}, determine whether T is a topology or not. Explanation The powerset P(S) of some set S is the set of all subsets of S. Example: S = {1,2,3} P(S) = {{}, {1}, {2}, {3}, {1,2}, {1,3}...