Given an array of integers, return a new array such that each element at index i of the new array is the product of all the numbers in the original array except the one at i. For example, if our input was [1, 2, 3, 4, 5], the expected output would be [120, 60, 40, 30, 24]. If our input was [3, 2, 1], the expected output would be [2, 3, 6].

O(n)arrayProductExcludingIndex.js

/**
Given an array of integers, return a new array such that each element at index i of the new array is the product of all the numbers in the original array except the one at i.

For example, if our input was [1, 2, 3, 4, 5], the expected output would be [120, 60, 40, 30, 24]. If our input was [3, 2, 1], the expected output would be [2, 3, 6].
*/

const productArray = (arr) => {
  const newArr = [];
  let product = 1;
  
  for (let i = 0; i < arr.length; i++) {
    product *= arr[i];
  }
  
  for (let i = 0; i < arr.length; i++) {
    newArr.push(product/arr[i]);
  }
  
  return newArr;
}