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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14
votes
5answers
304 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 ...
13
votes
3answers
423 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 ...
16
votes
5answers
645 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? ...
7
votes
4answers
646 views

Write an URL compressor

Today your goal is to invent URL compression. You must write two programs: a compressor and a decompressor. The compressor will be called with one URL on stdin and its output will be read on stdout. ...
8
votes
2answers
616 views

Write a GIF encoder

Yes, the good old GIF. Loved for its versatility, hated for its patents and partly obsoleted due to its limitations (and patents), GIF consists, at the core, of a color palette and a palette-indexed ...
7
votes
6answers
653 views

Writing code for three tasks

When you run your program first, it should print an integer sequence. The second run should print the 'Mary had a little lamb' song. The third run should produce an ASCII image file. Scoring Your ...
0
votes
1answer
229 views

CSS attribute selector efficient “greater than selector” code [closed]

The goal is to find a way better than the current best known way of encoding the index of a child HTML element, so that encoded indices have the following property. if (index_i >= index_p) { ...
28
votes
14answers
3k views

Sudoku Compression

Your job is to write a program (or two separate programs) in any language that: Can take a completed Sudoku board as input (in any logical format) and compress it into a string of characters Can ...
5
votes
1answer
351 views

Invent your own Unicode 7.0.0 encoding (as efficient as possible)

As you may know, the Unicode standard has room for 1,114,111 code points, and each assigned code point represents a glyph (character, emoji, etc.). Most code points are not yet assigned. Current ...
8
votes
2answers
354 views

Rosetta Stone Challenge: Run-Length Encoding v2.0

The goal of a Rosetta Stone Challenge is to write solutions in as many languages as possible. Show off your programming multilingualism! The Challenge We've done run-length encoding before but only ...
4
votes
1answer
218 views

Recover a bzip2 file

The popular .bz2 compression format is used to store all sorts of things. One of the more interesting features is that it consists of several independently decompressible blocks, allowing recovery of ...
6
votes
5answers
465 views

Thwart LZMA2 compression

Goal Create a program or pair of programs that collectively disrupt and fix files with the intent of preventing LZMA2 from working effectively. The disrupt and fix routines must be reciprocal, so ...
11
votes
1answer
498 views

Monopoly Compression

Given a string representing the current state of a game of Monopoly at the beginning of a player's turn, compress all the necessary data into the smallest output. Answers will be judged by output size ...
32
votes
2answers
1k views

Musical Tweet Challenge

This is the audio version of the Twitter image encoding challenge. Design an audio compression format that can represent at least one minute of music in 140 bytes or less of printable UTF-8-encoded ...
5
votes
2answers
462 views

Analysing the most common words in a text, and replacing them with a single byte

This is a very crude text encoding algorithm I came up with the other day. It won't work if the text has more than 256 different characters in it – but it does support Unicode, at least in my Python ...
4
votes
10answers
522 views

Golf an LZW encoder

Given an alphabet and a string, your job is to create the Lempel–Ziv–Welch compression of the string. Your implementation can either be a function with two parameters and a return value, or a full ...
25
votes
14answers
2k views

Smallest chess board compression

Write an algorithm or program that can encode and decode a chess board. The goal is to make the smallest representation of a chessboard that could be used (once decoded) to determine all movement ...
7
votes
2answers
553 views

Create self-extractor script (relaxed rules)

This is the target language-relaxed version of Generate a self-extractor application Create a program in any language, that takes an arbitrary binary input, and generates a valid program (also in any ...
4
votes
2answers
392 views

Generate a self-extractor application

Create a program in any language, that takes an arbitrary binary input, and generates a valid C++11 program, which when compiled and run will print this binary input. So you could do this (on linux ...
1
vote
1answer
468 views

Compressing a DNA-like string [closed]

my app is multiple choice test, where for each question the response results in a 4 letter string "eg" GTAC or ATGC or CATG, etc. There are always just 24 questions. so the final result is something ...
54
votes
9answers
4k views

Encode Images into Tweets (Extreme Image Compression Edition)

Based on the very successful Twitter image encoding challenge at Stack Overflow. If an image is worth 1000 words, how much of an image can you fit in 114.97 bytes? I challenge you to come up with a ...
6
votes
12answers
634 views

Output code-sized text

Output the same length of Lorem ipsum your code is! Rules: length is bits/8 length has to be positive code can't be identical to output no compression library shortest or super creative program in ...
7
votes
2answers
577 views

Compress data with context free grammars

It is possible to compress some kinds of data, such as human text or source code, with straight-line grammars. You basically create a grammar whose language has exactly one word – the uncompressed ...
0
votes
2answers
265 views

Storing a DNS name as compactly as possible in memory (preferably in C#) [closed]

What is the most compact way to encode/save DNS names in memory? For example, storing "www.google.com" as a string in .NET will result in the object being encoded as UTF-16, and it will consume twice ...
26
votes
9answers
3k views

Text compression and decompression — “Nevermore.”

With the recent discussion about the use of compression tools in code golf, I thought it would be a nice challenge to write your own text compressor and decompressor. Challenge: Write two programs: ...
7
votes
3answers
950 views

Lossy Text Compression

Background Of the 256 possible characters that a byte can represent, only a few of these are used under most circumstances. Couldn't we somehow take advantage of this, and make our text files smaller ...
13
votes
15answers
1k views

Run-Length Encoding

Write a program uses run-length encoding to shorten a list of non-negative integers it has to read in. You can assume the non-negative integers can fit in 32bit signed integers. Input Format The ...
5
votes
3answers
292 views

Compress programs

Write a program/script that decompresses and passes any compressed data appended at the end of the binary/file as standard input to a program specified as arguments. $ gzip --to-stdout input >> ...
9
votes
1answer
481 views

Write a compressing util for gzip files

The task of this challenge is as following: Write a program that reads a file of reasonable size (let's say <16 MB) from stdin or anywhere else (however you like, but must not be hardcoded), and ...