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_2 , String var_3 ) {
    StringBuilder var_5 = new StringBuilder ( ) ;
    int var_7 = 0 ;
    for ( int var_10 = var_2 . length ( ) - 1 , var_11 = var_3 . length ( ) - 1 ;
    var_10 >= 0 || var_11 >= 0 || var_7 == 1 ;
    var_10 -- , var_11 -- ) {
      int var_14 = var_10 < 0 ? 0 : var_2 . charAt ( var_10 ) - '0' ;
      int var_15 = var_11 < 0 ? 0 : var_3 . charAt ( var_11 ) - '0' ;
      var_5 . append ( ( var_14 + var_15 + var_7 ) % 10 ) ;
      var_7 = ( var_14 + var_15 + var_7 ) / 10 ;
    }
    return var_5 . reverse ( ) . toString ( ) ;
  }
  