comefrom: <qiyuangong>415_Add_Strings_1.java
code: public String addStrings(String num1, String num2) {
          StringBuilder sb = new StringBuilder();
          int carry = 0;
          for(int i = num1.length() - 1, j = num2.length() - 1; i >= 0 || j >= 0 || carry == 1; i--, j--){
              int x = i < 0 ? 0 : num1.charAt(i) - '0';
              int y = j < 0 ? 0 : num2.charAt(j) - '0';
              sb.append((x + y + carry) % 10);
              carry = (x + y + carry) / 10;
          }
          return sb.reverse().toString();
      }
masked: public String var_0 ( String var_1 , String var_2 ) {
    StringBuilder var_3 = new StringBuilder ( ) ;
    int var_4 = 0 ;
    for ( int var_5 = var_1 . length ( ) - 1 , var_6 = var_2 . length ( ) - 1 ;
    var_5 >= 0 || var_6 >= 0 || var_4 == 1 ;
    var_5 -- , var_6 -- ) {
      int var_7 = var_5 < 0 ? 0 : var_1 . charAt ( var_5 ) - '0' ;
      int var_8 = var_6 < 0 ? 0 : var_2 . charAt ( var_6 ) - '0' ;
      var_3 . append ( ( var_7 + var_8 + var_4 ) % 10 ) ;
      var_4 = ( var_7 + var_8 + var_4 ) / 10 ;
    }
    return var_3 . reverse ( ) . toString ( ) ;
  }
  