Adds Quick sort implementation in JavaScript and TypeScript

Author: NisargChokshi45

JavaScript/algorithms/sorting/quicksort.js

@@ -0,0 +1,79 @@
+/* Quick Sort
+
+Description: Quick sort is a divide-and-conquer algorithm that works by selecting a 'pivot' element from the array and partitioning the other elements into two sub-arrays according to whether they are less than or greater than the pivot. The sub-arrays are then sorted recursively.
+
+Time Complexity:
+- Best/Average Case: O(n log n)
+- Worst Case: O(n²)
+
+Space Complexity: O(log n)
+*/
+
+function quickSort(arr) {
+  if (arr.length <= 1) {
+    return arr;
+  }
+
+  const pivot = arr[Math.floor(arr.length / 2)];
+  const left = [];
+  const right = [];
+  const equal = [];
+
+  for (let element of arr) {
+    if (element < pivot) {
+      left.push(element);
+    } else if (element > pivot) {
+      right.push(element);
+    } else {
+      equal.push(element);
+    }
+  }
+
+  return [...quickSort(left), ...equal, ...quickSort(right)];
+}
+
+function runTests() {
+  console.log("---------- Quick Sort Test Cases ----------");
+
+  // Test 1: Regular unsorted array
+  const test1 = [64, 34, 25, 12, 22, 11, 90];
+  console.log("\nTest 1 - Original:", test1);
+  console.log("Test 1 - Sorted:", quickSort(test1));
+
+  // Test 2: Already sorted array
+  const test2 = [1, 2, 3, 4, 5];
+  console.log("\nTest 2 - Original:", test2);
+  console.log("Test 2 - Sorted:", quickSort(test2));
+
+  // Test 3: Reverse sorted array
+  const test3 = [5, 4, 3, 2, 1];
+  console.log("\nTest 3 - Original:", test3);
+  console.log("Test 3 - Sorted:", quickSort(test3));
+
+  // Test 4: Array with duplicates
+  const test4 = [3, 1, 4, 1, 5, 9, 2, 6, 5];
+  console.log("\nTest 4 - Original:", test4);
+  console.log("Test 4 - Sorted:", quickSort(test4));
+
+  // Test 5: Single element array
+  const test5 = [42];
+  console.log("\nTest 5 - Original:", test5);
+  console.log("Test 5 - Sorted:", quickSort(test5));
+
+  // Test 6: Empty array
+  const test6 = [];
+  console.log("\nTest 6 - Original:", test6);
+  console.log("Test 6 - Sorted:", quickSort(test6));
+
+  // Test 7: Large array
+  const test7 = [38, 27, 43, 3, 9, 82, 10];
+  console.log("\nTest 7 - Original:", test7);
+  console.log("Test 7 - Sorted:", quickSort(test7));
+
+  // Test 8: Array with negative numbers
+  const test8 = [-5, 2, -3, 8, -1, 0];
+  console.log("\nTest 8 - Original:", test8);
+  console.log("Test 8 - Sorted:", quickSort(test8));
+}
+
+runTests();

TypeScript/algorithms/sorting/quicksort.ts

@@ -0,0 +1,79 @@
+/* Quick Sort
+
+Description: Quick sort is a divide-and-conquer algorithm that works by selecting a 'pivot' element from the array and partitioning the other elements into two sub-arrays according to whether they are less than or greater than the pivot. The sub-arrays are then sorted recursively.
+
+Time Complexity:
+- Best/Average Case: O(n log n)
+- Worst Case: O(n²)
+
+Space Complexity: O(log n)
+*/
+
+function quickSort(arr: number[]): number[] {
+  if (arr.length <= 1) {
+    return arr;
+  }
+
+  const pivot: number = arr[Math.floor(arr.length / 2)];
+  const left: number[] = [];
+  const right: number[] = [];
+  const equal: number[] = [];
+
+  for (let element of arr) {
+    if (element < pivot) {
+      left.push(element);
+    } else if (element > pivot) {
+      right.push(element);
+    } else {
+      equal.push(element);
+    }
+  }
+
+  return [...quickSort(left), ...equal, ...quickSort(right)];
+}
+
+function runTests(): void {
+  console.log("---------- Quick Sort Test Cases ----------");
+
+  // Test 1: Regular unsorted array
+  const test1: number[] = [64, 34, 25, 12, 22, 11, 90];
+  console.log("\nTest 1 - Original:", test1);
+  console.log("Test 1 - Sorted:", quickSort(test1));
+
+  // Test 2: Already sorted array
+  const test2: number[] = [1, 2, 3, 4, 5];
+  console.log("\nTest 2 - Original:", test2);
+  console.log("Test 2 - Sorted:", quickSort(test2));
+
+  // Test 3: Reverse sorted array
+  const test3: number[] = [5, 4, 3, 2, 1];
+  console.log("\nTest 3 - Original:", test3);
+  console.log("Test 3 - Sorted:", quickSort(test3));
+
+  // Test 4: Array with duplicates
+  const test4: number[] = [3, 1, 4, 1, 5, 9, 2, 6, 5];
+  console.log("\nTest 4 - Original:", test4);
+  console.log("Test 4 - Sorted:", quickSort(test4));
+
+  // Test 5: Single element array
+  const test5: number[] = [42];
+  console.log("\nTest 5 - Original:", test5);
+  console.log("Test 5 - Sorted:", quickSort(test5));
+
+  // Test 6: Empty array
+  const test6: number[] = [];
+  console.log("\nTest 6 - Original:", test6);
+  console.log("Test 6 - Sorted:", quickSort(test6));
+
+  // Test 7: Large array
+  const test7: number[] = [38, 27, 43, 3, 9, 82, 10];
+  console.log("\nTest 7 - Original:", test7);
+  console.log("Test 7 - Sorted:", quickSort(test7));
+
+  // Test 8: Array with negative numbers
+  const test8: number[] = [-5, 2, -3, 8, -1, 0];
+  console.log("\nTest 8 - Original:", test8);
+  console.log("Test 8 - Sorted:", quickSort(test8));
+}
+
+runTests();