chore: Merge pull request TheAlgorithms#789 from devcer/master

Added Maximum product of 3 numbers in an array

Author: raklaptudirm

Dynamic-Programming/MaxProductOfThree.js

@@ -0,0 +1,38 @@
+/**
+ * Given an array of numbers, return the maximum product
+ * of 3 numbers from the array
+ * https://wsvincent.com/javascript-three-sum-highest-product-of-three-numbers/
+ * @param {number[]} arrayItems
+ * @returns number
+ */
+export function maxProductOfThree(arrayItems) {
+ // if size is less than 3, no triplet exists
+ let n = arrayItems.length
+ if (n < 3) throw new Error('Triplet cannot exist with the given array')
+ let max1 = arrayItems[0],
+ max2 = -1,
+ max3 = -1,
+ min1 = arrayItems[0],
+ min2 = -1
+ for (let i = 1; i < n; i++) {
+ if (arrayItems[i] > max1) {
+ max3 = max2
+ max2 = max1
+ max1 = arrayItems[i]
+ } else if (max2 === -1 || arrayItems[i] > max2) {
+ max3 = max2
+ max2 = arrayItems[i]
+ } else if (max3 === -1 || arrayItems[i] > max3) {
+ max3 = arrayItems[i]
+ }
+ if (arrayItems[i] < min1) {
+ min2 = min1
+ min1 = arrayItems[i]
+ } else if (min2 === -1 || arrayItems[i] < min2) {
+ min2 = arrayItems[i]
+ }
+ }
+ let prod1 = max1 * max2 * max3,
+ prod2 = max1 * min1 * min2
+ return Math.max(prod1, prod2)
+}

Dynamic-Programming/tests/MaxProductOfThree.test.js

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+import { maxProductOfThree } from '../MaxProductOfThree'
+
+describe('MaxProductOfThree', () => {
+ it('expects to throw error for array with only 2 numbers', () => {
+ expect(() => {
+ maxProductOfThree([1, 3])
+ }).toThrow('Triplet cannot exist with the given array')
+ })
+
+ it('expects to return 300 as the maximum product', () => {
+ expect(maxProductOfThree([10, 6, 5, 3, 1, -10])).toBe(300)
+ })
+
+ it('expects to return 300 as the maximum product', () => {
+ expect(maxProductOfThree([10, -6, 5, 3, 1, -10])).toBe(600)
+ })
+})