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MaxProductOfThree.js

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/**

* 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

const n = arrayItems.length

if (n < 3) throw new Error('Triplet cannot exist with the given array')

let max1 = arrayItems[0]

let max2 = null

let max3 = null

let min1 = arrayItems[0]

let min2 = null

for (let i = 1; i < n; i++) {

if (arrayItems[i] > max1) {

max3 = max2

max2 = max1

max1 = arrayItems[i]

} else if (max2 === null || arrayItems[i] > max2) {

max3 = max2

max2 = arrayItems[i]

} else if (max3 === null || arrayItems[i] > max3) {

max3 = arrayItems[i]

}

if (arrayItems[i] < min1) {

min2 = min1

min1 = arrayItems[i]

} else if (min2 === null || arrayItems[i] < min2) {

min2 = arrayItems[i]

}

const prod1 = max1 * max2 * max3

const prod2 = max1 * min1 * min2

return Math.max(prod1, prod2)

}