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]
76
questions
14
votes
11answers
695 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\$
...
2
votes
0answers
107 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
1answer
397 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 ...
28
votes
15answers
6k 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 ...
0
votes
4answers
352 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
2answers
696 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, ...
9
votes
2answers
608 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 ...
2
votes
7answers
357 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 ...
5
votes
4answers
476 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, ...
0
votes
4answers
400 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 ...
9
votes
33answers
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 ...
8
votes
3answers
438 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 "Palindrome ...
22
votes
10answers
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 ...
36
votes
19answers
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 ], ...
15
votes
4answers
773 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 ...
301
votes
23answers
39k 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 ...
26
votes
8answers
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 Road" ...
10
votes
12answers
1k 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 ...
18
votes
12answers
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 ...
8
votes
2answers
992 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 ...
11
votes
6answers
6k 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 ...
-6
votes
2answers
251 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&...
29
votes
11answers
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 ...
11
votes
13answers
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 ...
24
votes
1answer
742 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 ...
25
votes
21answers
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 ...
35
votes
9answers
2k 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 ...
9
votes
1answer
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
0answers
168 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 ...
7
votes
10answers
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 ...
2
votes
0answers
441 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
1answer
464 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 ...
17
votes
2answers
797 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 ...
32
votes
8answers
2k views
Latin square compression
A Latin square is a square that has no repeated symbols in the rows or columns:.
13420
21304
32041
04213
40132
And as many Sudoku players know, you don't need ...
16
votes
7answers
879 views
Send a cosmic call
The cosmic call is a message sent into space in 1999 and 2003.
It's made of 23 127*127px monochrome bitmap images, as detailed here.
Your mission is to write a program that displays the entire 127*...
33
votes
29answers
2k views
Is it a prefix code?
In information theory, a "prefix code" is a dictionary where none of the keys are a prefix of another. In other words, this means that none of the strings starts with any of the other.
For example, <...
30
votes
2answers
2k views
Compress an image to a 4 KiB preview
In this challenge you will be creating an image preview compression algorithm. It's goal is to
reduce an arbitrary image file to a 4 KiB preview image, that can be used to quickly identify images
with ...
13
votes
4answers
584 views
Strategies for representing a given large integer using arithmetic expression
I have a specific number in mind, but it's part of a challenge I'm doing, and I don't want people to do (all) the work for me.
Here is a number which has the same digits, but shuffled:
...
243
votes
36answers
44k views
Paint Starry Night, objectively, in 1kB of code
Note: Anders Kaseorg has been awarded the accept for now, to draw attention to his great answer, but the challenge is by no means over! I will award a 1000 point bounty to anyone who takes the top ...
12
votes
5answers
610 views
Implement a URL shortener
URLs are getting too long. So, you must implement an algorithm to shorten a URL.
i. The Structure of a URL
A URL has 2 main parts: a domain and a path. A domain is the part of the URL before the ...
22
votes
3answers
788 views
Golfing Strings
I have always failed to give an answer for kolmogorov-complexity challenges which require string compression, the main reason being that I don't know to use string compression tools as effectively as ...
8
votes
4answers
783 views
Write two programs that compresses and decompresses data
Challenge:
Create a program that compresses a semi-random string, and another program that decompresses it. The question is indeed quite similar to this one from 2012, but the answers will most ...
25
votes
6answers
3k views
Big big numbers
Whilst trying to golf several of my answers, I've needed to write large integers in as few characters as possible.
Now I know the best way to do that: I'll be getting you to be writing this program.
...
12
votes
1answer
738 views
Lossless English language text compression challenge [closed]
Challenge:
Your challenge (should you choose to accept it) is to compress and decompress the 5MB "Complete Works of William Shakespeare" as found here:
http://www.gutenberg.org/cache/epub/100/pg100....
0
votes
1answer
672 views
ASCII art compression
The following challenge is basically a simpler version of the one proposed by Dennis (Lossy ASCII art compression). I found the idea super interesting but a bit too convulted, and seeing as it didn't ...
21
votes
2answers
2k views
Lossy ASCII art compression
Background
PICASCII is a neat tool that converts images into ASCII art.
It achieves different degrees of brightness by using the following ten ASCII characters:
...
14
votes
4answers
572 views
Implement bzip2's run-length encoding
Background
After applying the BWT (as seen in Burrows, Wheeler and Back) and the MTF (as seen in Move to the printable ASCII front), the bzip2 compressor applies a rather unique form of run-length ...
19
votes
7answers
771 views
Move to the printable ASCII front
Background
The move-to-front transform (MTF) is a data encoding algorithm designed to improve the performance of entropy encoding techniques.
In the bzip2 compression algorithm, it is applied after ...
15
votes
3answers
635 views
Burrows, Wheeler and Back
Background
The Burrows–Wheeler transform (BWT) is a reversible permutation of the characters of a string that results in large runs of similar characters for certain types of strings such as plain ...
18
votes
5answers
833 views
Boggle Board Compression
When working on Non-Palindromic Polyglot Boggle, I found it quite tedious to pack the codes as efficiently as possible onto the Boggle board, even with only two strings. But we're programmers, right? ...
