Medium Article Snippet

iterative_approach_3.js

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

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

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

  product = 1; // reset product
  for(let j = inputArr.length - 1; j >= 0; j--) {
    product *= inputArr[j];
    const beforeIndex = productMap.get(j-1);

    if (beforeIndex) {
      const finalProduct = beforeIndex * product;
      productMap.set(j-1, finalProduct);
    } else {
      productMap.set(j-1, product);
    }
  }

  for(let k = 0; k < inputArr.length; k++) {
    resultArr.push(productMap.get(k));
  }

  return resultArr;
}

console.log(product(input));

Algorithmic Complexity:

O(3n) speed
O(2n) space

Previous Approach: https://gist.github.com/naveedn/b16bd0a15ba089c58187eeacf4448efa
Next Approach: https://gist.github.com/naveedn/c54b39521c0b07b0f9bde8ec020eda9d