Added descriptions for the following contracts:

* Compression I: RLE Compression
 * Compression II: LZ Decompression
 * Compression III: LZ Compression
This commit is contained in:
Staszek Welsh 2022-04-25 16:48:33 +01:00
parent 6e9f33470b
commit eed95cfa10

@ -306,3 +306,67 @@ The list contains the name of (i.e. the value returned by
| | | Input: [3, [[0, 1], [0, 2], [1, 2]]] |
| | | Output: [] |
+-----------------------------------------+------------------------------------------------------------------------------------------+
| Compression I: RLE Compression | | Run-length encoding (RLE) is a data compression technique which encodes data as a |
| | | series of runs of a repeated single character. Runs are encoded as a length, followed |
| | | by the character itself. Lengths are encoded as a single ASCII digit; runs of 10 |
| | | characters or more are encoded by splitting them into multiple runs. |
| | | |
| | | You are given a string as input. Encode it using run-length encoding with the minimum |
| | | possible output length. |
| | | |
| | | Examples: |
| | | aaaaabccc -> 5a1b3c |
| | | aAaAaA -> 1a1A1a1A1a1A |
| | | 111112333 -> 511233 |
| | | zzzzzzzzzzzzzzzzzzz -> 9z9z1z (or 9z8z2z, etc.) |
+-----------------------------------------+------------------------------------------------------------------------------------------+
| Compression II: LZ Decompression | | Lempel-Ziv (LZ) compression is a data compression technique which encodes data using |
| | | references to earlier parts of the data. In this variant of LZ, data is encoded in two |
| | | types of chunk. Each chunk begins with a length L, encoded as a single ASCII digit |
| | | from 1 - 9, followed by the chunk data, which is either: |
| | | |
| | | 1. Exactly L characters, which are to be copied directly into the uncompressed data. |
| | | 2. A reference to an earlier part of the uncompressed data. To do this, the length |
| | | is followed by a second ASCII digit X: each of the L output characters is a copy |
| | | of the character X places before it in the uncompressed data. |
| | | |
| | | For both chunk types, a length of 0 instead means the chunk ends immediately, and the |
| | | next character is the start of a new chunk. The two chunk types alternate, starting |
| | | with type 1, and the final chunk may be of either type. |
| | | |
| | | You are given an LZ-encoded string. Decode it and output the original string. |
| | | |
| | | Example: decoding '5aaabc340533bca' chunk-by-chunk |
| | | 5aaabc -> aaabc |
| | | 5aaabc34 -> aaabcaab |
| | | 5aaabc340 -> aaabcaab |
| | | 5aaabc34053 -> aaabcaabaabaa |
| | | 5aaabc340533bca -> aaabcaabaabaabca |
+-----------------------------------------+------------------------------------------------------------------------------------------+
| Compression III: LZ Compression | | Lempel-Ziv (LZ) compression is a data compression technique which encodes data using |
| | | references to earlier parts of the data. In this variant of LZ, data is encoded in two |
| | | types of chunk. Each chunk begins with a length L, encoded as a single ASCII digit |
| | | from 1 - 9, followed by the chunk data, which is either: |
| | | |
| | | 1. Exactly L characters, which are to be copied directly into the uncompressed data. |
| | | 2. A reference to an earlier part of the uncompressed data. To do this, the length |
| | | is followed by a second ASCII digit X: each of the L output characters is a copy |
| | | of the character X places before it in the uncompressed data. |
| | | |
| | | For both chunk types, a length of 0 instead means the chunk ends immediately, and the |
| | | next character is the start of a new chunk. The two chunk types alternate, starting |
| | | with type 1, and the final chunk may be of either type. |
| | | |
| | | You are given a string as input. Encode it using Lempel-Ziv encoding with the minimum |
| | | possible output length. |
| | | |
| | | Examples (some have other possible encodings of minimal length): |
| | | abracadabra -> 7abracad47 |
| | | mississippi -> 4miss433ppi |
| | | aAAaAAaAaAA -> 3aAA53035 |
| | | 2718281828 -> 627182844 |
| | | abcdefghijk -> 9abcdefghi02jk |
| | | aaaaaaaaaaa -> 1a911a |
| | | aaaaaaaaaaaa -> 1a912aa |
| | | aaaaaaaaaaaaa -> 1a91031 |
+-----------------------------------------+------------------------------------------------------------------------------------------+