415. Add Strings

easy

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"

Solution

class Solution {
public:
    string addStrings(string num1, string num2) {
        int carry = 0;
        int i = num1.size() - 1;
        int j = num2.size() - 1;
        string result;
        while (i >= 0 || j >= 0 || carry) {            
            int temp = carry;
            if (i>=0) {
                temp += num1[i] - '0';
                i--;
            }
            if (j>=0) {
                temp += num2[j] - '0';
                j--;
            }
            result = to_string(temp % 10) + result; 
            carry = temp / 10;        
        }
        return result;
    }
};