diff --git a/Maths/FindMaxRecursion.js b/Maths/FindMaxRecursion.js new file mode 100644 index 0000000000..db2325f4f5 --- /dev/null +++ b/Maths/FindMaxRecursion.js @@ -0,0 +1,42 @@ +/** + * @function findMaxRecursion + * @description This algorithm will find the maximum value of a array of numbers. + * + * @param {Integer[]} arr Array of numbers + * @param {Integer} left Index of the first element + * @param {Integer} right Index of the last element + * + * @return {Integer} Maximum value of the array + * + * @see [Maximum value](https://en.wikipedia.org/wiki/Maximum_value) + * + * @example findMaxRecursion([1, 2, 4, 5]) = 5 + * @example findMaxRecursion([10, 40, 100, 20]) = 100 + * @example findMaxRecursion([-1, -2, -4, -5]) = -1 + */ +function findMaxRecursion (arr, left, right) { + const len = arr.length + + if (len === 0 || !arr) { + return undefined + } + + if (left >= len || left < -len || right >= len || right < -len) { + throw new Error('Index out of range') + } + + if (left === right) { + return arr[left] + } + + // n >> m is equivalent to floor(n / pow(2, m)), floor(n / 2) in this case, which is the mid index + const mid = (left + right) >> 1 + + const leftMax = findMaxRecursion(arr, left, mid) + const rightMax = findMaxRecursion(arr, mid + 1, right) + + // Return the maximum + return Math.max(leftMax, rightMax) +} + +export { findMaxRecursion } diff --git a/Maths/test/FindMaxRecursion.test.js b/Maths/test/FindMaxRecursion.test.js new file mode 100644 index 0000000000..4772eeb1d3 --- /dev/null +++ b/Maths/test/FindMaxRecursion.test.js @@ -0,0 +1,58 @@ +import { findMaxRecursion } from '../FindMaxRecursion' + +describe('Test findMaxRecursion function', () => { + const positiveAndNegativeArray = [1, 2, 4, 5, -1, -2, -4, -5] + const positiveAndNegativeArray1 = [10, 40, 100, 20, -10, -40, -100, -20] + + const positiveArray = [1, 2, 4, 5] + const positiveArray1 = [10, 40, 100, 20] + + const negativeArray = [-1, -2, -4, -5] + const negativeArray1 = [-10, -40, -100, -20] + + const zeroArray = [0, 0, 0, 0] + const emptyArray = [] + + it('Testing with positive arrays', () => { + expect(findMaxRecursion(positiveArray, 0, positiveArray.length - 1)).toBe(5) + expect(findMaxRecursion(positiveArray1, 0, positiveArray1.length - 1)).toBe( + 100 + ) + }) + + it('Testing with negative arrays', () => { + expect(findMaxRecursion(negativeArray, 0, negativeArray.length - 1)).toBe( + -1 + ) + expect(findMaxRecursion(negativeArray1, 0, negativeArray1.length - 1)).toBe( + -10 + ) + }) + + it('Testing with positive and negative arrays', () => { + expect( + findMaxRecursion( + positiveAndNegativeArray, + 0, + positiveAndNegativeArray.length - 1 + ) + ).toBe(5) + expect( + findMaxRecursion( + positiveAndNegativeArray1, + 0, + positiveAndNegativeArray1.length - 1 + ) + ).toBe(100) + }) + + it('Testing with zero arrays', () => { + expect(findMaxRecursion(zeroArray, 0, zeroArray.length - 1)).toBe(0) + }) + + it('Testing with empty arrays', () => { + expect(findMaxRecursion(emptyArray, 0, emptyArray.length - 1)).toBe( + undefined + ) + }) +})