feat: add array rotation algorithms

Author: Zahir-R

Data-Structures/Array/RotateArray.js

@@ -0,0 +1,57 @@
+/**
+ * Rotates an array to the right by k positions
+ * @param {number[]} array - The array to rotate
+ * @param {number} k - Number of positions to rotate
+ * @returns {number[]} - New array rotated to the right by k positions
+ * @throws {TypeError} - If input is not an array
+ */
+export function rotateRight(array, k) {
+  if (!Array.isArray(array)) {
+    throw new TypeError('Input must be an array')
+  }
+
+  if (!Number.isInteger(k) || k < 0) {
+    throw new TypeError('Rotation count must be a non-negative integer')
+  }
+
+  const length = array.length
+  if (length === 0) return []
+
+  const normalizedK = k % length
+  const rotated = new Array(length)
+
+  for (let i = 0; i < length; i++) {
+    rotated[(i + normalizedK) % length] = array[i]
+  }
+
+  return rotated
+}
+
+/**
+ * Rotates an array to the left by k positions
+ * @param {number[]} array - The array to rotate
+ * @param {number} k - Number of positions to rotate
+ * @returns {number[]} - New array rotated to the left by k positions
+ * @throws {TypeError} - If input is not an array
+ */
+export function rotateLeft(array, k) {
+  if (!Array.isArray(array)) {
+    throw new TypeError('Input must be an array')
+  }
+
+  if (!Number.isInteger(k) || k < 0) {
+    throw new TypeError('Rotation count must be a non-negative integer')
+  }
+
+  const length = array.length
+  if (length === 0) return []
+
+  const normalizedK = k % length
+  const rotated = new Array(length)
+
+  for (let i = 0; i < length; i++) {
+    rotated[i] = array[(i + normalizedK) % length]
+  }
+
+  return rotated
+}

Data-Structures/Array/test/RotateArray.test.js

@@ -0,0 +1,53 @@
+import { rotateRight, rotateLeft } from '../RotateArray.js'
+
+describe('rotateRight', () => {
+  it('should rotate array to the right by k positions', () => {
+    expect(rotateRight([1, 2, 3, 4, 5], 2)).toEqual([4, 5, 1, 2, 3])
+    expect(rotateRight([1, 2, 3], 1)).toEqual([3, 1, 2])
+  })
+
+  it('should handle rotation count larger than array length', () => {
+    expect(rotateRight([1, 2, 3], 5)).toEqual([2, 3, 1])
+    expect(rotateRight([1], 10)).toEqual([1])
+  })
+
+  it('should return empty array for empty input', () => {
+    expect(rotateRight([], 3)).toEqual([])
+  })
+
+  it('should handle zero rotation', () => {
+    expect(rotateRight([1, 2, 3], 0)).toEqual([1, 2, 3])
+  })
+
+  it('should throw TypeError for invalid inputs', () => {
+    expect(() => rotateRight('not an array', 1)).toThrow(TypeError)
+    expect(() => rotateRight([1, 2, 3], -1)).toThrow(TypeError)
+    expect(() => rotateRight([1, 2, 3], 1.5)).toThrow(TypeError)
+  })
+})
+
+describe('rotateLeft', () => {
+  it('should rotate array to the left by k positions', () => {
+    expect(rotateLeft([1, 2, 3, 4, 5], 2)).toEqual([3, 4, 5, 1, 2])
+    expect(rotateLeft([1, 2, 3], 1)).toEqual([2, 3, 1])
+  })
+
+  it('should handle rotation count larger than array length', () => {
+    expect(rotateLeft([1, 2, 3], 5)).toEqual([3, 1, 2])
+    expect(rotateLeft([1], 10)).toEqual([1])
+  })
+
+  it('should return empty array for empty input', () => {
+    expect(rotateLeft([], 3)).toEqual([])
+  })
+
+  it('should handle zero rotation', () => {
+    expect(rotateLeft([1, 2, 3], 0)).toEqual([1, 2, 3])
+  })
+
+  it('should throw TypeError for invalid inputs', () => {
+    expect(() => rotateLeft('not an array', 1)).toThrow(TypeError)
+    expect(() => rotateLeft([1, 2, 3], -1)).toThrow(TypeError)
+    expect(() => rotateLeft([1, 2, 3], 1.5)).toThrow(TypeError)
+  })
+})