Add Strings
Difficulty: Easy
Category: DSA
Topics: String
Asked at: Facebook, Adobe, Google, Wayfair, Microsoft, Square, Uber, Bloomberg, Amazon, Oracle
Given two non-negative integers, `num1` and `num2` represented as string, return the sum of `num1` and `num2` as a string.
Example 1:
Input: num1 = "11", num2 = "123"
Output: "134"
Example 2:
Input: num1 = "456", num2 = "77"
Output: "533"
Example 3:
Input: num1 = "0", num2 = "0"
Output: "0"
Constraints:
`1 <= num1.length, num2.length <= 104`
`num1` and `num2` consist of only digits.
`num1` and `num2` don't have any leading zeros except for the zero itself.
Follow up: Could you solve it without using any built-in `BigInteger` library or converting the inputs to integer directly?