feat: compression

src/compression/README.md

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+# Compression
+
+Compression is a technique to reduce the size of data. It is used to save space and time in data storage and transmission.
+
+Includes the following algorithms:
+
+- Run Length Encoding

src/compression/rle.test.ts

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+import { assertEquals, describe, it } from "../deps.ts";
+import { RLE } from "./rle.ts";
+
+describe("rle", () => {
+  it("should be able to compress a string", () => {
+    assertEquals(RLE.encode("aaaabbbccd"), "4a3b2c1d");
+  });
+
+  it("should be able to decompress a string", () => {
+    assertEquals(RLE.decode("4a3b2c1d"), "aaaabbbccd");
+  });
+
+  it("should be able to compress and decompress a string", () => {
+    const original = "aaaabbbccd";
+    const encoded = RLE.encode(original);
+    const decoded = RLE.decode(encoded);
+
+    assertEquals(decoded, original);
+  });
+});

src/compression/rle.ts

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+// run length encoding
+
+export class RLE {
+  static encode(data: string): string {
+    let result = "";
+    let count = 1;
+
+    for (let i = 1; i < data.length; i++) {
+      if (data[i] === data[i - 1]) {
+        count++;
+      } else {
+        result += count + data[i - 1];
+        count = 1;
+      }
+    }
+    result += count + data[data.length - 1];
+
+    return result;
+  }
+
+  static decode(data: string): string {
+    let result = "";
+    let count = "";
+
+    for (let i = 0; i < data.length; i++) {
+      if (/\d/.test(data[i])) {
+        count += data[i];
+      } else {
+        result += data[i].repeat(Number(count));
+        count = "";
+      }
+    }
+
+    return result;
+  }
+}