Questions tagged [compression]

Related to compressing or decompressing arbitrary data. Challenges which relate to compressing a single specific input should instead be tagged [kolmogorov-complexity]

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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 <...
  • 10.8k
8 votes
6 answers
284 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\$ ...
21 votes
16 answers
4k views

Who needs 8 bits for one character?

Given a string and the characters used to encode it, you need to compress the string by only using as many bits as each character needs. You will return the character codes for each character needed ...
  • 10.8k
-2 votes
1 answer
160 views

Program compressor

Choose a language and write a program in the language that: Take a valid program of the language as input, Output a string(bytearray, etc.). It needn't be a valid program. Only finite valid inputs ...
  • 13k
13 votes
8 answers
575 views

Compress and decompress

Your task is to make a bidirectional compressor. It takes a list of bytes as input and returns a list of bytes as output. It has the property than whenever it is iterated twice it returns the original ...
  • 6,775
10 votes
2 answers
415 views

Smallest possible Scratch 3.0 project file (SB3)

The objective is to make the smallest SB3 file that can simply be imported into Scratch 3.0 without a "The project file that was selected failed to load" error. Any means can be used, like ...
9 votes
0 answers
323 views

Jelly compression quine

The golfing language Jelly has a very complex and clever string compression system which I'm not going to go into depth about here. You can find a very good explanation here. Basically, Jelly's string ...
  • 31.9k
14 votes
2 answers
489 views

What's my TIO uniqueness?

Try it online! currently has 680 listed languages, all of which are searchable. For most of those languages, when searching for it, you don't have to enter the entire string. For example, entering <...
49 votes
7 answers
7k views

Reverse Zip Bomb

A zip bomb is a compressed file, designed so that unpacking it yields the biggest file possible. These are fairly well known, and there are examples of 42 KB files which expand into multiple petabytes ...
20 votes
3 answers
493 views

Decompress an integer, Jelly style

Jelly has compressed string literals, using the “...» delimiters. The way these work is by interpreting the ... as a base-250 ...
12 votes
9 answers
2k views

Naïve compression

using Prefixed Length Code We are going to implement a compression of text (string, array/list of characters/bytes) by simple substitution of each character by a binary code, based on the frequency of ...
  • 20.6k
10 votes
5 answers
971 views

Breaking Bad - ize any string (compression) [duplicate]

The TV series "Breaking Bad" replaced the letters Br and Ba with a periodic-table like representation, printing [Br35]eaking [Ba56]d. Create a program ...
32 votes
20 answers
3k views

Golf a golf chart

Given a distance in meters as an integer \$60\le d \le 260\$, return the number of clubs that may be used according to the following arbitrary chart, where both \$min\$ and \$max\$ are inclusive: <...
  • 171k
25 votes
14 answers
2k views

Print a Ternary Value

Put simply, you are to print out the following number: ...
  • 3,097
11 votes
10 answers
2k views

Cheat activated

Background The game Grand Theft Auto: San Andreas went down in history also thanks to its wide selection of cheats. They're almost 90 and anyone who has ever touched this game, no doubt has tried ...
  • 2,153
37 votes
12 answers
2k views

lc's dvntrs n Wndrlnd

The task Today's special offer: consonants and punctuation for FREE! Your program or function will be given as input the first 6 paragraphs of Lewis Carroll's famous novel Alice's Adventures in ...
  • 171k
18 votes
34 answers
1k views

Compactify the input

Given a word, your task is to compact it by saving its first character and removing any other vowel (aeiou). Input Your input can be the word in STDIN, a function argument or any other input format ...
19 votes
14 answers
2k views

Let's decompress a bit

Given a compressed string \$s\$ made of printable ASCII characters (32 to 126), your task is to print or return the original text by applying this simple decompression algorithm: Start with \$k=0\$ ...
  • 171k
2 votes
0 answers
167 views

Predictor Generator [closed]

Write a program that when given a string \$S\$, it generates a program of the same language as itself. The generated program, when given a continuous substring of \$S\$, should predict the next ...
9 votes
1 answer
450 views

Caddyshack or: How to compress already-golfed code

In golf, a knowledgable caddie helps an already good golfer to be even better. In this challenge, you build a "caddie" to help you code golf. In particular, your caddie will compress golfed code in ...
30 votes
17 answers
7k views

.-...--..---.-...--..... the red-nosed reindeer

Can you recover a sequence of letters from a sequence of dots and dashes? In Morse code, x is represented by -..-, but without ...
3 votes
4 answers
508 views

Compress my Malbolge!

Background Malbolge is truly intriguing language. But programs written in it are also extraordinairly huge (and in some cases, unpostable on PPCG). Your challenge (shall you accept it) is, to ...
14 votes
2 answers
995 views

Create the least compressible picture

"A picture is worth a thousand words"—so the old saying goes. The average word is about four characters long, so a picture conveys 4kB of information. But how much entropy, rather than information, ...
  • 1,477
9 votes
2 answers
1k views

ASCII Maze Compression

Challenge Design a compression algorithm specialized for compressing ASCII mazes. You will need to create both a compression algorithm and a decompression algorithm. Your score will be based on the ...
  • 9,791
2 votes
7 answers
376 views

Countries by Area

Challenge Given two non negative integers a < b, output all countries, from the below Top 100 Countries, where area is between ...
  • 2,777
6 votes
4 answers
1k views

Generate Matlab plot markers

Matlab has a useful command for visualizing data: plot. It draws data points using "markers" in 2-D space, connecting them with lines; however, for this challenge, ...
  • 12.3k
1 vote
4 answers
456 views

Send the pairs in smallest output

Write two programs A and B. Program A (the encoder) takes 1024 pairs of integers \$(k,v)\$, where \$0≤k<2^{32}\$ and \$0≤v<1024\$, and all \$k\$ will be different. It will output a single ...
  • 13k
9 votes
33 answers
1k views

Output some reserved words

For a computer language, a reserved word is a word that cannot be used as an identifier, such as the name of a variable, function, or label. For other computer languages, keywords can be considered as ...
  • 2,777
8 votes
3 answers
558 views

Compress to Impress

Inspired by both the challenge "Unique is Cheap" by @Laikoni, where the score is based on the challenge itself, as well as the JavaScript (ES6) answer of @ETHproductions for the "...
22 votes
10 answers
2k views

Compressing the Atomic Ionization Energies

This is a different type of compression challenge. In a normal kolmogorov-complexity challenge, you are required to recreate a list exactly. Here, you are allowed to round the values in any way you ...
  • 28.6k
36 votes
18 answers
3k views

Bracket Expansion!

Your challenge is to expand some brackets in a program's input as shown: Find a string s between two matching brackets [ and ], ...
  • 13.3k
15 votes
4 answers
915 views

Palindrome Compression

Challenge Write a program that compresses and decompresses ASCII text losslessly. It should be specialized to work well with palindromes, including case-insensitive and punctuation-insensitive ...
  • 9,791
318 votes
24 answers
44k views

Write Moby Dick, approximately

Here is a 1.2Mb ASCII text file containing the text of Herman Melville's Moby-Dick; or, The Whale. Your task is to write a program or function (or class, etc. -- see below) which will be given this ...
  • 7,182
27 votes
8 answers
2k views

Somewhere On The Tube ...But On Which Lines?

The London Underground A.K.A. The Tube is the oldest underground railway in the world, it currently consists of eleven lines* servicing 267 named stations (strictly 269** stations since "Edgware ...
10 votes
12 answers
2k views

Simple State Sales Tax Calculator

Sales taxes in the United States are complicated, to say the least. Generally, there's a state sales tax (there are a handful of states that do not collect a state sales tax), but there could also be ...
  • 42.9k
20 votes
12 answers
4k views

All your base 97 are belong to us

Many programming languages are written using solely printable ASCII, tabs and newlines. These 97 characters are then stored in 8-bit bytes (which are actually capable of holding 256 different ...
  • 9,346
9 votes
2 answers
1k views

Smallest chess game compression

Inspiration: Heavily inspired by Smallest chess board compression I decided to make a similar but distinctly different competition. tl;dr Take the file Chess_Games.txt and compress it as much as ...
  • 235
11 votes
6 answers
7k views

Compressing RLE data to draw ASCII art

This question is based on what I came up with to answer another question. Sometimes the questions here ask to draw some ASCII art. One simple way to store the data for the art is RLE (run-length ...
  • 12.6k
-6 votes
2 answers
289 views

Output the Wikipedia article for Kolmogorov Complexity

Your job is to output the html of the current version (at the time of this writing) of the Wikipedia page for Kolmogorov complexity: https://en.wikipedia.org/w/index.php?title=Kolmogorov_complexity&...
  • 7,079
30 votes
11 answers
2k views

Which wire to cut

This task is about compressing and processing a sequence of conditionals. In the game Keep Talking and Nobody Explodes, a bomb defuser must disarm a bomb with the help of instructions relayed by ...
  • 139k
11 votes
13 answers
1k views

The weird and wild bean game

Maybe some of you already know this game: you have a collection of jelly beans of different colors. For every color, the bean can have different tastes, some are good and some are bad, and you cannot ...
  • 12.6k
25 votes
1 answer
825 views

Maximal discrepancy-2 sequence with minimal entropy

Background As noted in the PPCG challenge Compress a maximal discrepancy-2 sequence – which inspired this challenge – the authors of the paper Computer-Aided Proof of Erdős Discrepancy Properties ...
  • 207k
29 votes
24 answers
3k views

Converting "0xUsernames"

0xUsernames There's so many people using a messaging service that they're running out of space to store all the usernames! To fix this, they are going to start storing usernames as hexadecimal, where ...
  • 14k
35 votes
10 answers
3k views

Help me recognise my monster

Background The computer game NetHack dates from 1987, before the use of graphics in computer games was widely established. There are lots of monsters in the game, and potentially a lot need to fit on ...
's user avatar
9 votes
1 answer
1k views

The Most Durable Pokemon Types

Background This question is similar to this one. I have provided all of the information needed below. If you are familiar with the other challenge then note that we are ranking all defenses instead ...
1 vote
0 answers
188 views

Self compressing/decompressing program [closed]

Challenge: Write a lossless encoder/decoder that is able to compress its own source code. Usage: progname encode Encodes ...
  • 317
8 votes
10 answers
2k views

DNA Encode a String

Challenge You must write an encoder (and a separate decoder) which takes a string as input and outputs the string encoded in the style of a strand of DNA. DNA DNA is made up of four types of ...
  • 22.8k
2 votes
0 answers
489 views

100KB image compression [closed]

Your task is to, given an image, compress it to 100000 bytes or less, while following all of the below rules: No cheating/loopholes. Your code must not be optimized to work best only on the test set ...
20 votes
1 answer
508 views

Diff compression [closed]

For this challenge, you need to compress a diff. A diff is some data that represents the difference between two strings. For this challenge, you need to provide one or more programs that can: Input ...
18 votes
2 answers
875 views

Thwart Lepton compression

Dropbox recently released Lepton (GitHub), a method that losslessly compresses JPEG images round-trip, saving an average of 22%. Because of the pigeonhole principle, any general compression algorithm ...
  • 3,267