Medium Article Snippet

iterative_approach_2.js

const input = [1,3,5,7];

function product(inputArr) {
  const beforeMap = new Map();
  const afterMap = new Map();
  const resultArr = [];

  let product = 1;
  let reverseProduct = 1;

  for(let i = 0; i < inputArr.length; i++) {
    product *= inputArr[i];
    beforeMap.set(i+1, product);
  }

  for(let j = inputArr.length - 1; j >= 0; j--) {
    reverseProduct *= inputArr[j];
    afterMap.set(j-1, reverseProduct);
  }

  for(let k = 0; k < inputArr.length; k++) {
    let beforeIndex = beforeMap.get(k);
    let afterIndex = afterMap.get(k);

    if (beforeIndex && afterIndex) {
      resultArr.push(beforeIndex * afterIndex);
    } else if (beforeIndex) {
      resultArr.push(beforeIndex);
    } else {
      resultArr.push(afterIndex);
    }
  }

  return resultArr;
}

console.log(product(input));

Algorithmic Complexity:

speed: O(3n)
space: O(3n)

Previous Approach: https://gist.github.com/naveedn/93b7eaa01da0dbc9d3a1e7e45894cf15
Next Approach: https://gist.github.com/naveedn/00955f4928c1e3d3177eff40967b2fa1