From 5f8d4d447a85fb4aeb065983ab275a582d4ff07b Mon Sep 17 00:00:00 2001
From: Daniel <67126972+ddaniel27@users.noreply.github.com>
Date: Sun, 23 Jun 2024 00:20:25 -0500
Subject: [PATCH] [Compressor] RLE Compressor implementation (#1671)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

* [Solution] Project euler challenge 19 with tests

* update leap year function

* Remove unnecessary, confusingly placed comments

* [COMPRESSOR] RLE

* [COMPRESSOR] RLE style fixed

---------

Co-authored-by: Lars Müller <34514239+appgurueu@users.noreply.github.com>
---
 Compression/RLE.js           | 38 ++++++++++++++++++++++++++++++++++++
 Compression/test/RLE.test.js | 13 ++++++++++++
 2 files changed, 51 insertions(+)
 create mode 100644 Compression/RLE.js
 create mode 100644 Compression/test/RLE.test.js

diff --git a/Compression/RLE.js b/Compression/RLE.js
new file mode 100644
index 000000000..81a153864
--- /dev/null
+++ b/Compression/RLE.js
@@ -0,0 +1,38 @@
+/*
+ * 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 }
diff --git a/Compression/test/RLE.test.js b/Compression/test/RLE.test.js
new file mode 100644
index 000000000..0094b5b7e
--- /dev/null
+++ b/Compression/test/RLE.test.js
@@ -0,0 +1,13 @@
+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')
+  })
+})