Leetcode | Solution of Subtract the Product and Sum of Digits of an Integer in JavaScript

April 3rd, 2020
3 min read

In this post, we will solve Subtract the Product and Sum of Digits of an Integer from leetcode and compute it's time and space complexities. Let's begin.

Problem Statement

The question can be found at leetcode Subtract the Product and Sum of Digits of an Integer problem

The problem states that we are given an integer and we need to return the difference between the product and sum of its digits


Here's the approach that we'll take

  • We'll declare two variables product and sum and initialize it with 1,0
  • Next, we will loop over all the digits of the number and find their product and sum iteratively
  • At last, we will return their difference

We have discussed the approach, I urge you to go ahead on leetcode and give it another try. emoji-smile

If you are here, it means something went wrong in implementation or you are just too lazy emoji-smile. In any case, let's see a simple implementation of the above logic.
var subtractProductAndSum = function (n) {
  let product = 1, sum = 0;

  while (n > 0) {
    const digit = n % 10;
    n = parseInt(n / 10);

    product = product * digit;
    sum += digit

  return product - sum

The only thing to note in the solution is how we find digits of a number. We iterate until the number is greater than zero. Finding modulus of the number by 10 will give us the last digit of the number. Similarly, dividing by 10 would give us the next number. For example - if the number is 123, modulus 10 would be 3 and divided by 10 would be 12.

Finally, the number would converge to 0. At last, we return the difference of the product and sum.

Here are the stats on submission

Status: Accepted
Runtime: 52ms
Memory: 34MB

Time and space complexity

Time complexity

We are looping over the digits of the integer, so time complexity would depend on the number of digits in the number O(len n) or simply O(n)

Space complexity

We are not using any extra space except for a couple of variables. So space complexity is constant, O(1).


So, we solved the Subtract the Product and Sum of Digits of an Integer problem by using a simple while loop and calculated the time and space complexities.

I hope you enjoyed solving this question. This is it for this one, complete source code for this post can be found on my Github Repo. Will see you in the next one.

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