Questions tagged [code-golf]
Code-golf is a competition to solve a particular problem in the fewest bytes of source code.
9,548
questions
26
votes
21answers
5k views
Egg, sausage, bacon and spam (lovely spam!)
You are given four integers: \$e,s,b\in\{0,1\}\$ and \$S\in \{0,1,2,4\}\$, where \$e,s,b,S\$ stand for egg, sausage, bacon and spam respectively.
Your task is to figure out whether the corresponding ...
3
votes
7answers
204 views
String permutations
Print the biggest-size subset of strings in the input that are all permutations of each other. If there are ties, any one will do. If no strings are permutations of each other (for example, only one ...
23
votes
6answers
6k views
ASCII Pizza (no pineapple)
I like pizza!
Task
Given the radius of a pizza and a list of ingredients, create the corresponding ascii pizza!
Example size 4 pizza with mozzarella cheese, olives and ham:
...
10
votes
23answers
1k views
Sort list by types
Rules
You will receive as input a list that contains integers and strings. Your task is to move all of the strings to the end of the list and all of the integers to the beginning of the list.
This ...
15
votes
26answers
2k views
Drawing one-liner
CodeDrawing one-liner
Teaser
Behold this formidable drawing:
Can you draw this in a single stroke? Give it a try.
Can you do this one, now:
Give it a try.
How it works
These "make this drawing ...
21
votes
17answers
2k views
Answer templating
Context
Just look around! Whenever someone posts an answer, the same template is followed over and over again! A first line with the byte count and language name. Then the code. Then the TIO link. ...
12
votes
9answers
1k views
Integer Logarithm
Objective
Take \$a \in ℤ_{>1}\$ and \$b \in ℤ_+\$ as inputs. Write a function \$f\$ such that:
$$
f(a,b) =
\left\{
\begin{array}{ll}
\log_ab & \quad \text{if} \space \log_ab \in ℚ ...
20
votes
2answers
689 views
Are They Similar Polygons?
Task
Given the x,y coordinates (coordinates are guaranteed to be integers) of the vertices of two simple polygons in clockwise or anti-clockwise order. Output a Truthy value if both the polygons are ...
6
votes
4answers
601 views
Count regex matches
Your task
Given a simple regular expression, you have to count how many strings of length n have a match of length n with the ...
17
votes
35answers
2k views
Is it a doubling sequence?
A doubling sequence is an array of numbers where each subsequent number is at least twice the previous number.
Given an ordered list of numbers, determine if the numbers in the list (\$n_{x}\$) have ...
36
votes
37answers
8k views
Is this a triangle?
Task
Write a function/program that, given three positive integers a, b and c, prints a ...
7
votes
13answers
167 views
Computational Parity Party! [duplicate]
The computational parity of an integer is defined as 1 if the integer has an odd number of set bits, and 0 otherwise. (src).
Input
You will receive one nonnegative integer that you will take the ...
20
votes
40answers
3k views
Reversed Iota's
I didn't invent this challenge, but I find it very interesting to solve.
For every input number, e.g.:
4
Generate a range from 1 to that number:
...
14
votes
12answers
319 views
Combinations of stepwise increasing integers
Working on something in probability theory, I stumbled across another combinatorical exercise. These are always fun to solve, searching for intelligent approaches. Of course, one can use brute force ...
23
votes
7answers
2k views
10-pin bowling split spare
Bowling
Bowling is a game where, essentially, each player gets 10 turns to:
Take 2 attempts at knocking down 10 pins arranged in a triangle.
between turns the pins are reset
from the 1st to the 2nd ...
1
vote
0answers
56 views
Shortest Sorting algorithm [duplicate]
So, you need to create the shortest sorting algorithm with a resonably fast run time. It could be any sorting algorithm.
Test code:
...
34
votes
37answers
5k views
Lonely Multiplication
Based on this question from Code Review.
Given precisely three positive integers, return the product of all of the distinct inputs. If none of the inputs are distinct, return 1. That is, implement ...
1
vote
1answer
114 views
Self-loathing program/function [duplicate]
Simple task, write a program/function that returns error if and only if presented with itself.
The program must give a valid output for any input other than itself.
For the error part, you can only ...
0
votes
0answers
99 views
Let's learn a bit French: 99 Bottles [duplicate]
The 99 bottles in French
The lyrics of the song goes like this:
...
1
vote
1answer
130 views
Name an arbitrary string [closed]
This should be easy: given an arbitrary string, your program will give it a name.
Requirements
Your program will accept an input of a UTF8 string, and output a string representing the input's "name",...
9
votes
5answers
185 views
Count switches in a smallest square root sequence mod \$2^n\$
Definition
For any \$a\equiv1\ (\text{mod }8)\$ and \$n\ge3\$, there are exactly 4 roots to the equation \$x^2\equiv a\ (\text{mod }2^n)\$. Now, let \$x_k(a)\$ be the smallest root to the equation \$...
9
votes
1answer
190 views
Count the Shantens
Introduction to Mahjong tiles
Mahjong (麻雀) is a board game that originates from China. Mahjong tiles used in this challenge are in Unicode points U+1F000 – U+1F021:
...
30
votes
29answers
5k views
How far should I sum?
How far should I sum?
The harmonic series is the "infinite sum" of all the fractions of the form \$\frac1n\$ for \$n\$ positive integer. I.e. the harmonic series is
$$\frac11 + \frac12 + \frac13 + \...
22
votes
26answers
3k views
Can I join the music box?
The magic music box (MMB)
This explains the motivation for the challenge, feel free to ignore.
The magic music box is a word game played by a group of people, where one is the owner of the magic ...
1
vote
5answers
373 views
Write some Random English
Your Goal:
Given an odd integer input n greater than 1, generate a random English word of length n. An English word is one in ...
3
votes
5answers
269 views
Implement a Caesar Cipher with a Digit Shift
I assume everyone here is familiar with the Caesar Cipher that shifts letters to a certain index. https://en.wikipedia.org/wiki/Caesar_cipher for those who still needs introduction.
But, we can all ...
1
vote
0answers
129 views
What does the shortest pseudo-random algorithm look like? [closed]
After seeing some impossibly short solutions in this SE, I began to wonder what code someone could come up with to build a pseudo-random number generator. Now given that I am new to programming, I ...
27
votes
12answers
3k views
Compress 8 bits to 6 when certain bit patterns will never occur
Consider an eight bit number in which an even position bit will never be 1 if one of its neighbors is 0 (considering MSB and LSB as neighbors). There are fewer than 64 such numbers, so there is at ...
21
votes
35answers
2k views
Give me Triangles [duplicate]
Given an integer n>0, write a program that will output an "isosceles" Triangle out of #'s of height n.
Examples:
...
22
votes
22answers
2k views
Mountain range numbers
Mountain range number
A number is a mountain range number if the inequalities satisfied by their consecutive digits alternate. In a way, looking at the number's digits should exhibit a ...
27
votes
25answers
2k views
The Magical Piper
An old test for programmers, taken from here (Note: in italian).
Along a road (denoted by '_'), there is a Magical Piper (denoted by '...
29
votes
19answers
4k views
Print this maximally long URL
Task
This one is simple. We want to compress a URL, but don't trust URL shorteners.
Write a program that prints to stdout (or a 0-argument function that returns) the following, working URL:
http://...
4
votes
3answers
186 views
Shortest POSIX command line that eagerly removes dual newline sequences
Example:
echo -ne 'a\n\nb\nc\n\n\n\nd\n\n\n' | your-command
should output the same as
echo -ne 'ab\ncd\n'
Watch out, some ...
11
votes
3answers
1k views
Intersection of circles – How can I reduce this golf code to 127 bytes?
I started a CodeWars kata in Python, just two days ago, related to code golf.
Task: Given two congruent circles a and b of radius r, return the area of their intersection rounded down to the nearest ...
15
votes
12answers
1k views
It's all about the sum of the digits
The sequence
Given an integer \$n>0\$, we define \$a(n)\$ as the lowest positive integer such that there exists exactly \$n\$ positive integers smaller than \$a(n)\$ whose sum of digits is equal ...
21
votes
17answers
2k views
Concentric rings on a snub square tiling
This challenge takes place on the snub square tiling.
Start by choosing any triangle, and color it \$c_1\$.
Next, find all tiles which touch this triangle at any vertex, and color them \$c_2\$. Next,...
26
votes
7answers
1k views
Roll a cube to a target position
You have your very heavy cubical box on a flat floor at position (0,0). All you can do with it is roll it in four cardinal directions (east, north, west, south). Your task is to bring it to a target ...
27
votes
24answers
4k views
Calculate the Progressive Mean™
Disclaimer: This challenge is inspired by a coding error I once made.
Okay, time for a maths lesson. A normal mean average looks like this:
...
14
votes
15answers
1k views
Find the Inverse Neighbor Pairs
Definition
We say a pair of integers \$(a,b)\$, where \$0<a<b<N\$ and \$N\$ is an integer larger than 4, is an inverse neighbor pair respect to \$N\$ if \$ab\equiv1\text{ }(\text{mod }N)\$ ...
18
votes
13answers
1k views
Number of palindrome splits
In this task you will take as input a non-negative integer \$n\$, and output the number of pairs of non-negative integers \$a,b\$ such that both are palindromes*, \$a \leq b\$, and \$a+b = n\$. For ...
20
votes
24answers
2k views
Power-Ending Patterns
When you look at the last decimal digit of each power of a non-negative integer a repeating pattern forms. For example, 3:
...
15
votes
26answers
1k views
pleTriwapt Sgpin (Triplet Swapping)
Intro/Background
I was looking at a Flybuys card at Coles recently and noticed that if I took something like this:
Source, randomly found on the Internet
And swapped some words around, I'd get ...
14
votes
1answer
295 views
Solve a meta-knowledge puzzle
Alice and Bob are perfect logicians trapped on an island with a puzzle generator. Although they can instantly solve the Riemann hypothesis and P=NP just by thinking about it, rather than doing ...
14
votes
14answers
869 views
Computing a specific coefficient in a product of polynomials
Generator functions
This gives the context for why this challenge came to life. Feel free to ignore.
Generator functions are a nice way of encoding the solution to a problem of combinatorics. You ...
19
votes
13answers
963 views
Walk home one step at a time
You're at integer coordinates \$(x,y)\$ facing one of North, South, East, or West. Your goal is to walk home to \$(0,0)\$. At each step, you may do one of:
Walk one step in the current facing ...
27
votes
66answers
4k views
Repeat every other character in string starting with second character
Requirements:
Take a single word as input with only lowercase alphabetical characters (a-z)
Output a string where every other character is repeated, with the first repeated character being the second ...
5
votes
3answers
243 views
Choose 3 strings and output the exact minimum Hamming distance between any pair
Consider \$3\$ binary strings of length \$n\$ chosen independently and uniformly at random. We are interested in computing the exact expected minimum Hamming distance between any pair. The Hamming ...
33
votes
12answers
3k views
How many countries are in the European Union?
Tonight, 31 January 2020, Brexit will happen and the United Kingdom will leave the European Union, the first time that the number of EU member states will decrease.
Your job is to take a date and ...
11
votes
1answer
312 views
Write a Whitespace Interpreter
Challenge:
Your challenge is to write an interpreter for Whitespace. Given a string consisting of spaces, tabs, newlines, and potential other characters, as well as possible inputs for the Whitespace ...
13
votes
18answers
2k views
Given a list of strings, find all elements which are still in the list when any character is deleted
Write a program using the fewest bytes of source code which given a list of strings finds all elements which are still in the list when any character is deleted.
For example, given a list of all ...
