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[Compressor] RLE Compressor implementation (TheAlgorithms#1671)
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* [Solution] Project euler challenge 19 with tests

* update leap year function

* Remove unnecessary, confusingly placed comments

* [COMPRESSOR] RLE

* [COMPRESSOR] RLE style fixed

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Co-authored-by: Lars Müller <[email protected]>
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ddaniel27 and appgurueu authored Jun 23, 2024
1 parent 5844242 commit 5f8d4d4
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38 changes: 38 additions & 0 deletions Compression/RLE.js
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/*
* RLE (Run Length Encoding) is a simple form of data compression.
* The basic idea is to represent repeated successive characters as a single count and character.
* For example, the string "AAAABBBCCDAA" would be encoded as "4A3B2C1D2A".
*
* @author - [ddaniel27](https://github.com/ddaniel27)
*/

function Compress(str) {
let compressed = ''
let count = 1

for (let i = 0; i < str.length; i++) {
if (str[i] !== str[i + 1]) {
compressed += count + str[i]
count = 1
continue
}

count++
}

return compressed
}

function Decompress(str) {
let decompressed = ''
let match = [...str.matchAll(/(\d+)(\D)/g)] // match all groups of digits followed by a non-digit character

match.forEach((item) => {
let [count, char] = [item[1], item[2]]
decompressed += char.repeat(count)
})

return decompressed
}

export { Compress, Decompress }
13 changes: 13 additions & 0 deletions Compression/test/RLE.test.js
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import { Compress, Decompress } from '../RLE'

describe('Test RLE Compressor/Decompressor', () => {
it('Test - 1, Pass long repetitive strings', () => {
expect(Compress('AAAAAAAAAAAAAA')).toBe('14A')
expect(Compress('AAABBQQQQQFG')).toBe('3A2B5Q1F1G')
})

it('Test - 2, Pass compressed strings', () => {
expect(Decompress('14A')).toBe('AAAAAAAAAAAAAA')
expect(Decompress('3A2B5Q1F1G')).toBe('AAABBQQQQQFG')
})
})

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