Given two non-negative integers num1 and num2 represented as string, return the sum of num1 and num2.
Note:
num1 and num2 is < 5100.num1 and num2 contains only digits 0-9.num1 and num2 does not contain any leading zero.1 class Solution { 2 public String addStrings(String num1, String num2) { 3 StringBuilder sb = new StringBuilder(); 4 int carry = 0; 5 int i = num1.length() - 1, j = num2.length() - 1; 6 while (i >= 0 || j >= 0 || carry == 1){ 7 int x = i < 0 ? 0 : num1.charAt(i) - ‘0‘; 8 int y = j < 0 ? 0 : num2.charAt(j) - ‘0‘; 9 sb.append((x + y + carry) % 10); 10 carry = (x + y + carry) / 10; 11 i--; 12 j--; 13 } 14 return sb.reverse().toString(); 15 } 16 }
原文：https://www.cnblogs.com/beiyeqingteng/p/12271848.html