Here is the interview question prompt, presented for reference.

Let's build a very basic calculator by programming it! You've probably seen one that look similar to this:

But we won't be building a physical calculator (HardwareDaily will need to wait!)-- instead, we'll be writing a simple program that can serve as one. Can you write a function that will evaluate a simple expression string without using your language's eval method?

const expr = "2 + 2";
calculator(expr)
// 4

expr = "2 + 2"
calculator(expr)
# 4

It should also be able to handle positive and negative symbols +,-, parentheses (), and spaces.

let expr = "3 - 1 + 2";
calculator(expr)
// 4

expr = "(2+(4+2)-1)-(5+8)"
calculator(expr)
// -6

expr = "3 - 1 + 2"
calculator(expr)
# 4

expr = "(2+(4+2)-1)-(5+8)"
calculator(expr)
# -6

Assume for now that you don't need to handle multiplication or division cases.

Constraints

• Length of the given string <= 100000
• The numbers present in the string will be a single digit number
• Expected time complexity : O(n)
• Expected space complexity : O(n)

You can see the full challenge with visuals at this link.