Add Two Large Numbers Represented as Strings
Given two non-negative integers represented as strings, return their sum as a string.
The numbers may be too large for standard numeric data types. You must perform the addition without using any big-integer library or converting the complete strings into numeric values.
Method Signature
String addLargeNumbers(String firstNumber, String secondNumber)
firstNumber is the string representation of the first non-negative integer.secondNumber is the string representation of the second non-negative integer.- Returns the sum of
firstNumber and secondNumber as a string.
Rules
- Each input contains only digits from
'0' to '9'.
- Inputs do not contain leading zeros unless the entire number is
"0".
- The returned string must not contain unnecessary leading zeros.
- Standard big-integer libraries must not be used.
- The complete input strings must not be converted directly into built-in numeric types.
Constraints
1 ≤ firstNumber.length() ≤ 100,0001 ≤ secondNumber.length() ≤ 100,000firstNumber and secondNumber contain only decimal digits.
Examples
Example 1
addLargeNumbers(firstNumber = "875", secondNumber = "968")
Output: "1843"
Example 2
addLargeNumbers(firstNumber = "99999999999999999999", secondNumber = "7")
Output: "100000000000000000006"
Example 3
addLargeNumbers(firstNumber = "0", secondNumber = "45000000000000000000")
Output: "45000000000000000000"