# All Questions

10,506 questions
7k views

### Sum of Powers of 2

The Challenge Given an integer input x where 1 <= x <= 255, return the results of powers of two that when summed give <...
1k views

### The Path Of The Wildebeest

Golf a program or function which gives the $n^{\text{th}}$ location of the wildebeest who starts at square $1$ on an infinite chessboard which is numbered in an anti-clockwise square spiral, where ...
1k views

### Spot all (anti)diagonals with duplicated values

Challenge: Given a matrix input, determine the amount of diagonals and anti-diagonals with duplicated numbers. So if we have a matrix like this: ...
1k views

### Draw a path made by direction changers

This challenge takes place on a grid. ...
278 views

### Partition a square grid into parts of equal area

This challenge is based on the following puzzle: You are given an n by n grid with n cells ...
3k views

### Pointer jumping

Suppose we have an array $\texttt{ps}$ of length $n$ with pointers pointing to some location in the array: The process of "pointer jumping" will set every pointer to the location the pointer it ...
480 views

### Prime Difference [duplicate]

Given an integer n, output the smallest prime such that the difference between it and the next prime is at least n. For example, if n=5, you would output ...
5k views

### Who will win the election?

This is a challenge in which two people, 1 and 2, are running for office. People deterministically vote in certain ways in the world of 1 and 2, which can allow for the candidates to figure out the ...
746 views

### Binary self-rotation

Given a binary 3D array, for each layer, cyclically rotate up each of its columns as many steps as indicated by the binary encoding of the columns of the layer above it, and then cyclically rotate ...
150 views

### No-alphanumeric code exec

Introduction In most interpreted languages, there is an operation that will run code generated at runtime. It generally requires alphanumeric characters to refer to this operation. Write a program, ...
2k views

### Connect 4: Spot the Fake!

The bank has been broken into, and all the local mafia thugs have an unusual alibi: they were at home playing Connect 4! In order to assist with the investigation, you are asked to write a program to ...
280 views

### Count the Closed Polygons

Input: An NxM grid or multi-line string (or other reasonable input-format), containing only printable ASCII (unicode range ...
4k views

It is very hard to remember my password, so I came up with a way to generate a password. The way I generate my password is from a word or a sentence, following these steps: Start from left to right ...
387 views

### Matrix rotation sort

Lets define a non-empty, unsorted and finite matrix with unique numbers as follow: $$N = \begin{Bmatrix} 4&5&7\\1&3&6 \end{Bmatrix}$$ Lets define 4 matrix moves as: ↑* (up): Moves a ...
4k views

### Increment a GUID

Inspired by a recent Daily WTF article... Write a program or function that takes a GUID (string in the format XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX, where each X ...
246 views

### Is it Valid Modified UTF-8?

UTF-8 is a relatively simple way to encode Unicode codepoints in a variable-width format such that it doesn't easily confuse code that isn't Unicode aware. UTF-8 overview Bytes in the range of 1-...
6k views

### Dig a border trench

Background: Too many illegal immigrants from Blandia are crossing the border to Astan. The emperor of Astan has tasked you with digging a trench to keep them out, and Blandia must pay for the expenses....
3k views

### Equal, sum or difference!

Write shortest possible code that will return true if the two given integer values are equal or their sum or absolute difference is 5. Example test cases: ...
198 views

### Work out $x^y$ using only addition and subtraction [duplicate]

The challenge is to implement a function or program that takes two numbers, $x$ and $y$ and return the result of $x^y$. The program cannot use any other mathematical operation other than $+$ ...
78 views

### Chess move validation [duplicate]

Write a program that accepts chess moves, validate them and shows the results. The program should: Check wheter or not a move is valid Check if a king is in check or in checkmate Process the changes ...
3k views

### Matrix Jigsaw Puzzles

Input: An integer n Two equal-sized square matrices (with their width/height being a multiple of n) Output: One of two ...
1k views

### Unix timestamp to datetime string

Given a unix timestamp as an input, give a datetime string, in a format like so: "YYMMDD.HHmm" Rules The input is a number (integer) of a millisecond-precise UNIX epoch time (milliseconds since 1970 ...
327 views

### Matrix Jigsaw Puzzle Pieces

(Randomly inspired by https://codegolf.meta.stackexchange.com/a/17272/42963) Given a rectangular matrix of digits (i.e., 0 - 9), output the "pieces" of the matrix ...
668 views

### Number of $n$-carbon alkanes

Given a positive number $n$, find the number of alkanes with $n$ carbon atoms, ignoring stereoisomers; or equivalently, the number of unlabeled trees with $n$ nodes, such that every node has ...
4k views

### What are the repeating Fibonacci Digits?

As you probably know, a Fibonacci Number is one which is the sum of the previous two numbers in the series. A Fibonacci Digit™ is one which is the sum of the two previous digits. For instance, for ...
272 views

### Nested lists as printable 2D objects [closed]

I don't know if something like this exists already (and I'm not finding the right key words) but if not, it felt like it could be an interesting coding puzzle. The challenge is, to take an ...
285 views

### Range interval insert which should split into unique ranges

Given a range and a list thereof, while keeping the existing intervals in the list unchanged, split the additional range into sub-intervals and add them to the list, such that all the ranges in the ...
502 views

### An Séimhiú agus an tUrú

An Séimhiú agus an tUrú In Irish Gaelic (Gaeilge) there are a number of ways that the start of a word can be changed. The most common of these are lenition (an séimhiú) and eclipsis (an t-urú) ...
2k views

### Enumerate each series of identical numbers in-place

Given a list of strictly positive integers, go through each distinct number and replace all occurrences of it with successive indices (zero or one based) of a new series. Examples ...
419 views

### Mis-decode a date

Background Inspired by a now deleted question by John Burger from which I quote: Now obviously no human made this mistake. It's a mis-decode of something - perhaps the ISBN? My question is: ...
2k views

### Multi-level marketing “legs” investment rule

Multi-level marketing related challenge. A peer wants to get rewarded. So it attracted N investors (N>=1), each i-th ...
129 views

### Pattern Finder - Find Repeated Pattern in String [closed]

Introduction This is a little challenge with the goal of identifying repeated pattern "blocks" in a string, and outputting them with their frequency of occurence from left to right. A friend asked ...
896 views

### Write a function/method that takes in a string and spells that word out using the NATO Phonetic Alphabet. Titlecase optional

Write a program that takes in a string and spells that word out using the NATO Phonetic Alphabet. The mapping is as follows: ...
1k views

### How many consecutive descending numbers in my number?

2019 has come and probably everyone has noticed the peculiarity of this number: it's in fact composed by two sub-numbers (20 and 19) representing a sequence of consecutive descending numbers. ...
251 views

### Execute Triangularity Move

TL;DR for those not interested: Look at the test cases at the bottom. Have a program/function that outputs the 2D list displayed for the given input. Introduction: On November 15th, 2018 puzzle ...
1k views

### Clock (transliterate) Cipher

Introduction: I have loads of different ciphers stored in a document I once compiled as a kid, I picked a few of the ones I thought were best suitable for challenges (not too trivial, and not too ...
11k views

### Oreoorererereoo

Oreoorererereoo Given an input string that is similar to the word "oreo", give an ASCII representation of the cookie that is as wide as the input string (to ensure cookie stability). Rules The ...
293 views

### Surreal Numbers

Surreal Numbers Surreal numbers are one way of describing numbers using sets. In this challenge you will determine the value of a surreal number. Intro A surreal number consists of two sets: a left ...
80 views

### Remove indentation [duplicate]

Write a program which removes any common leading spaces from the input string. For example, if the least indented line started with 3 spaces, and every other line has ...
815 views

### Length of the Longest Descent

Your task is to determine the length of the longest descent down a "mountain" represented as a grid of integer heights. A "descent" is any path from a starting cell to orthogonally adjacent cells with ...
2k views

### Find if a list is an ABC-triple

Three positive integers A, B, C are ABC-triple if they are coprime, with A < B and satisfying the relation : A + B = C Examples : 1, 8, 9 is an ABC-triple ...
161 views

### Min-Max GHC command line error bytes to bytes of source code

GHC command line errors can be horrible, lets make them as bad as possible. To disincentivize very long programs use the following formula to calculate your "score". ...
108 views

### Order of Elements of the Rubik's Cube [duplicate]

Introduction All the possible moves and their combinations of a Rubik's Cube form a group. A group in general is a set with some binary operation defined on it. It must contain a neutral element with ...
46 views

### Polynomial to String [duplicate]

I'm new to code-golf, but I was trying to solve this problem myself, and thought there must be a much "better"/shorter way of doing it. Given a sequence (list) of numbers $a_0, a_1,\cdots,a_n$, ...
2k views

### Collapsing numbers

Let's define the a function on natural numbers $n$, written as base 10 digits $d_k\; d_{k-1}\; \dotsc\; d_1\; d_0$, as follows: As long as there are equal adjacent digits $d_i\;d_{i-1}$, ...
1k views

### Get the date of the nth day of week in a given year and month

Introduction Often, people refer to dates as the "second Friday in August, 2018" or the "fourth Sunday in March, 2012". But it's hard to tell what date that is! Your task to is to write a program ...
769 views

### Most contributing rows

Given a non-empty matrix of non-negative integers, answer which unique rows contribute most to the sum total of elements in the matrix. Answer by any reasonable indication, for example a mask of the ...
445 views

### Count the contiguous submatrices

Migrated from chat Given two non-empty non-negative integer matrices A and B, answer the number of times A occurs as a contiguous, possibly overlapping, submatrix in B. Examples/Rules 0. There may ...