All Questions
13,232
questions
23
votes
23
answers
10k
views
`lol` is an ambigram, `dad` isn't
Given a word, decide if it is an ambigram.
When rotated:
b > q
d > p
l > l
n > u
o > o
p > d
q > b
s > s
u > n
x > x
z > z
Assume ...
- 1,311
14
votes
8
answers
2k
views
But is it a pretty place?
Your challenge, should you choose to accept it, is to take as input:
A program in DirectionLang (as an ASCII string consisting of DirectionLang instructions)
A list of pairs of integers, henceforth ...
- 1,443
23
votes
18
answers
4k
views
What's the best die to roll?
The "standard" polyhedral game dice have 4, 6, 8, 10, 12 and 20 sides. (Yes, I know that there are two 10-sided dice which together make a d100, but we're ignoring that right now.)
If I want ...
- 89.4k
5
votes
1
answer
1k
views
fastest matrix multiplication on x86
This challenge requires integration with C, so you can stop reading if you're not interested.
Matrix multiplication is a simple operation, but the performance depends a lot on how efficiently the code ...
- 2,263
10
votes
6
answers
727
views
Counting Rhythms
The Narrative
You are a bad musician. You never bothered to learn how to count rhythms. To remedy this shortcoming, you decide to write a program that will tell you how to count in any given time ...
- 1,357
28
votes
21
answers
4k
views
Add a hidden language to a polyglot
Inspired/mostly copied but I don't think it's a dupe. Also Inspired.
In this challenge, you will create polyglots that include all languages from previous answers, and another language which you won't ...
- 31.5k
7
votes
4
answers
965
views
Invert a Non-commutative Function
Intro
Imagine a list of elements and their outcomes when some non-commutative function is applied to them. For example, we will use the elements Rock, ...
- 2,395
19
votes
15
answers
1k
views
Sample integers that sum to one hundred
Given a positive integer n, randomly output n non negative integers that sum to one hundred. n will be at most 200. The output should be present as a list of integers (not sorted).
Your random sample ...
- 643
12
votes
5
answers
488
views
Whyte Notation Translator
Whyte Notation is a classification method mainly for steam locomotive, that classifies by wheel arrangement. On a steam locomotive ( we're only focusing on non articulated locomotives here ), the ...
- 2,101
15
votes
10
answers
728
views
Determine Uilta Pitch Accent
Uilta is a minority tungusic language spoken in the far east of Russia.
A neat thing about Uilta is that it has pitch accent which can be predicted by a computer program. In this challenge we are ...
- 89.4k
7
votes
12
answers
554
views
Calculate the Lowest Even-Harmonic of the Values in a List
PROBLEM
For a list of numbers, list: Find the lowest possible integer, x, which is optimally close to the whole number even-...
1
vote
0
answers
133
views
Figure out the least amount of duplicate data to fill a quota [closed]
You are given 100 arrays/sets of 5-8 numbers between 1-20. If you combine all the arrays you will always get at least one of each number (1-20), so don't worry about an "unsolvable" case. ...
7
votes
1
answer
217
views
Find run ascending lists faster
In this question I asked you to determine if a run ascending list could be made. It was code-golf so naturally most the answers are very slow. But what if we want it to be fast. In this challenge I ...
- 89.4k
18
votes
13
answers
2k
views
Straighten my corners... diagonally
We can arrange the positive integers like this:
1_| 2 | 5 | 10
4___3_| 6 | 11
9___8___7_| 12
16 15 14 13
That is, in L-shaped brackets expanding down and right ...
- 31.5k
34
votes
37
answers
4k
views
Previous Fibonacci number
The sequence of Fibonacci numbers is defined as follows:
\$
F_0 = 0 \\
F_1 = 1 \\
F_n = F_{n-1} + F_{n-2}
\$
Given a Fibonacci number, return the previous Fibonacci number in the sequence. You do not ...
- 22.2k
18
votes
31
answers
2k
views
Reverse hex cipher
Characters in strings are sometimes represented as their ASCII hexadecimal codes. Printable characters have two hex digits in their representation. Swapping those digits leads to another character, ...
- 12.1k
33
votes
33
answers
5k
views
Eh, codegolf shmodegolf
This challenge is about implementing Shm-reduplication, originating in Yiddish, where one takes a word, duplicates it, and replaces the first syllable in the second word with "Shm" in order ...
- 663
16
votes
16
answers
1k
views
Divisible subset sums
Inspired by the recent 3Blue1Brown video
Consider, for some positive integer \$n\$, the set \$\{1, 2, ..., n\}\$ and its subsets. For example, for \$n = 3\$, we have
$$\emptyset, \{1\}, \{2\}, \{3\}, \...
- 47.5k
13
votes
8
answers
915
views
Can a run ascending list be made?
A run ascending list is a list such that runs of consecutive equal elements are strictly increasing in length. For example [1,1,2,2,1,1,1] can be split into three ...
- 89.4k
18
votes
28
answers
4k
views
Generate All 8 Knight's Moves
Introduction
In chess, Knights can move two squares in one direction, and then one square in an orthogonal direction. On an x/y plane, these can be thought of as being a relative change of coordinates,...
- 180
13
votes
12
answers
2k
views
I want 8 bits for every character!
This is the reverse of this challenge.
Given an encoded list of codepoints and the characters used to encode it, you need to decompress it to its original string.
For example, given the encoded list <...
- 8,986
18
votes
12
answers
1k
views
In between fractions
Given two positive integer fractions \$x\$ and \$y\$ such that \$x < y\$, give the fraction \$z\$ with the smallest positive integer denominator such that it is between \$x\$ and \$y\$.
For example ...
- 89.4k
7
votes
24
answers
2k
views
Find the nth Fibonacci number, where n is the mth Fibonacci number
Introduction
If \$\newcommand{\fib}{\operatorname{fib}}\fib(x)\$ calculates the \$x\$th Fibonacci number, write a program that calculates \$\fib(\fib(m))\$ for any integer value of \$m \ge 0\$. (Of ...
- 195
14
votes
13
answers
745
views
Find the dimensions of a ragged list
For any ragged list its dimensions will be a list of non-negative integers defined as follows:
Elements that are not a list will have dimensions \$\textbf{[}\,\,\textbf{]}\$.
An empty list has ...
- 89.4k
6
votes
2
answers
234
views
Solve the Zany car game
The Zany Car Game is a tile matching game. You are given a number of tiles, with coloured cars split into a top and bottom half. To win the game, you need to find a square arrangement of the tiles so ...
- 1,201
10
votes
13
answers
2k
views
Robbers: Smallest subset of characters required for Turing Completeness
This is the robbers' challenge. The cops' one is here.
In Fewest (distinct) characters for Turing Completeness, the goal is to find the minimum number of characters which make a language Turing ...
- 17.6k
27
votes
30
answers
7k
views
Smallest subset of characters required for Turing Completeness
In Fewest (distinct) characters for Turing Completeness, the goal is to find the minimum number of characters which make a language Turing Complete...in other words, allow it to do any computation ...
- 17.6k
12
votes
15
answers
5k
views
LOOOOONG TEEEEEXT
Definition of long text
Long text usually shows emphasis, for instance, loooooool or yaaaaaaaaaay. Usually the vowel is ...
- 1,311
16
votes
21
answers
2k
views
Apartment Building
Draw an "apartment" building according to the specifications below.
Basic Rules
Take, as input, the number of floors of the building.
Return a building with that many floors meeting the ...
- 1,308
6
votes
1
answer
459
views
Irradiated Polyglots
Design a function or program that, when run normally, outputs the triangular numbers. However, when any single character is deleted, the program/function should not function in the original ...
- 1,308
2
votes
1
answer
265
views
King of the Cards
King of the Cards
Code available here!
In this King of the Hill challenge, you must write a bot that can play Crazy Eights. This is a card game often played by children, in which the objective is to ...
- 3,410
12
votes
8
answers
782
views
Count the Liberties - Advanced
Here's an advanced version of the Count the Liberties challenge.
The definitions of the terms liberty and group are the same as the previous challenge, so have a look at the previous one for details, ...
- 2,263
17
votes
26
answers
2k
views
Alternating sums of multidimensional arrays
Given a multidimensional array, find the recursive alternating sum. An alternating sum is simply the sum of an array, where every other item (starting with the second) is negated. For example, the ...
- 17.6k
13
votes
9
answers
2k
views
Magic: the Gathering - Colour Sorting
Related: Deck Names Friends or Foes Paying for Spells
The Magic: the Gathering card game has five colours of magical mana: white (W), blue (U), black (B), red (R), and green (G). Cards can be any of ...
- 2,087
-2
votes
3
answers
183
views
Graphical Hello World [closed]
In this challenge, you will create the shortest graphical program that displays exactly "Hello, world!"
You will need no input.
You might be asking yourself, "what does he mean by ...
- 165
14
votes
24
answers
2k
views
There's more than one way to skin a set
Given a set of positive integers \$ S \$, output the set of all positive integers \$ n \$ such that \$ n \$ can be made by summing a subset of \$ S \$ in more than one different way, i.e., that are ...
- 22.2k
4
votes
1
answer
148
views
BitCycle Metagolf
Background
BitCycle is a two-dimensional Turing-complete programming language involves moving bits around a playfield.
Because I am too lazy to write BitCycle programs myself, you will be writing a ...
- 5,712
18
votes
23
answers
3k
views
Crossing a Lily Pond
The Narrative
You are a frog who is at the edge of a pond with waterlilies. You would like to cross the pond without getting wet, so you plan to jump from lily to lily. There is, however, one problem: ...
- 1,357
11
votes
9
answers
413
views
Convert Alpha-2 to Alpha-3
The Task
The task is easy: given an Alpha-2 country code, output the Alpha-3 equivalent. The input may be in any case you choose, and the output in any consistent case of your choosing. Here are the ...
- 3,347
-3
votes
2
answers
197
views
King of the Hill: Greed Control [duplicate]
King of the Hill: Greed Control
What is Greed Control
Greed control is a multiplayer round-based game
in which in every round, a player bet a number inside
a ...
- 1,311
7
votes
2
answers
264
views
Write a (simplified) BitCycle interpreter
Implement a function or program that can run simplified BitCycle code. The functions you must implement are:
<^>v: Change the direction of a bit to the ...
- 1,308
11
votes
14
answers
1k
views
Draw the Archimedean Spiral
Overview
I was playing with Desmos and discovered a really cool spiral:
Doing some research, I discovered that this spiral was the Archimedian spiral. Every point on the spiral is exactly \$\theta\$ ...
- 3,347
10
votes
15
answers
338
views
center a matrix [closed]
The words "center a" probably give flashbacks to any decent HTML developer. Luckily, we are not working with divs, we are working with matrices.
Given a matrix where w=h, and given a "...
- 691
8
votes
6
answers
269
views
Random Pixels Image Compression
Challenge:
Given an integer \$n\$, guaranteed to be \$\geq2\$ and a power of 2, we are going to draw multiply boards either side-by-side or below one another, where the first has dimensions of \$n\$ ...
- 107k
21
votes
13
answers
2k
views
Bitwise XOR of floats
This is different from Floating Point XOR, and more in the spirit of a comment by R.. GitHub STOP HELPING ICE on that challenge, but I thought of this idea independently.
Generalized XOR
The bitwise ...
- 313
-4
votes
2
answers
77
views
Is it a good chord?
Is it a good chord?
Definition of a chord:
We define a chord as three notes together.
Definition of a ...
- 1,311
4
votes
18
answers
2k
views
Palindromic Powers
Powers
We define an important power as a number that can be represented as \$ x^y \$ where \$ x ≥ 2 \$ and \$ y ≥ 2 \$.
Palindrome
We define an ...
- 1,311
27
votes
5
answers
4k
views
Haplololololololology!
Haplology
Haplology is a linguistic term:
the omission of one occurrence of a sound or syllable that is repeated within a word, for example probly for probably.
For this challenge, it means ...
- 2,671
14
votes
10
answers
1k
views
Storing a band matrix
Related challenge
A band matrix is a matrix whose non-zero entries fall within a diagonal band, consisting of the main diagonal and zero or more diagonals on either side of it. (The main diagonal of a ...
- 33.3k
-3
votes
6
answers
493
views
Connecting Dots
Connecting Dots
We define a type of question on the test, connecting the dots
Question parameters
There are two parameters. Suppose they are 5 and ...
- 1,311