All Questions

30
votes
55answers
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 <...
23
votes
3answers
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 ...
17
votes
14answers
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: ...
25
votes
5answers
1k views

Draw a path made by direction changers

This challenge takes place on a grid. ...
17
votes
1answer
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 ...
21
votes
23answers
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 ...
10
votes
14answers
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 ...
32
votes
11answers
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 ...
13
votes
6answers
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 ...
-8
votes
2answers
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, ...
35
votes
3answers
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 ...
8
votes
1answer
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 ...
26
votes
25answers
4k views

Generate a password

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 ...
12
votes
3answers
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 ...
30
votes
23answers
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 ...
9
votes
4answers
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-...
58
votes
20answers
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....
32
votes
35answers
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: ...
1
vote
2answers
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 \$+\$ ...
1
vote
0answers
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 ...
24
votes
15answers
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 ...
8
votes
21answers
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 ...
10
votes
15answers
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 ...
16
votes
4answers
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 ...
30
votes
12answers
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 ...
3
votes
6answers
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 ...
6
votes
3answers
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 ...
7
votes
13answers
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) ...
24
votes
38answers
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 ...
7
votes
11answers
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: ...
10
votes
15answers
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 ...
5
votes
0answers
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 ...
17
votes
21answers
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: ...
18
votes
17answers
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. ...
5
votes
2answers
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 ...
12
votes
14answers
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 ...
58
votes
42answers
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 ...
5
votes
1answer
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 ...
0
votes
1answer
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 ...
8
votes
7answers
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 ...
16
votes
23answers
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 ...
3
votes
0answers
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". ...
9
votes
0answers
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 ...
0
votes
0answers
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\$, ...
23
votes
18answers
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}\$, ...
17
votes
16answers
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 ...
16
votes
18answers
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 ...
12
votes
13answers
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 ...
2
votes
3answers
123 views

All the digisibles [duplicate]

A natural number (written in the decimal base) is qualified as digisible if and only if it fulfills the following 3 conditions: none of its digits is zero, all the digits that compose it are ...
6
votes
5answers
191 views

Find equally-weighted complete graphs

Graph theory is used to study the relations between objects. A graph is composed of vertices and edges in a diagram such as this: ...

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