comefrom: <qiyuangong>541_Reverse_String_II_1.java
code: public String reverseStr(String s, int k) {
          char[] a = s.toCharArray();
          for (int start = 0; start < a.length; start += 2 * k) {
              int i = start, j = Math.min(start + k - 1, a.length - 1);
              while (i < j) {
                  char tmp = a[i];
                  a[i++] = a[j];
                  a[j--] = tmp;
              }
          }
          return new String(a);
      }
masked: public String var_0 ( String var_2 , int var_3 ) {
    char [ ] var_5 = var_2 . toCharArray ( ) ;
    for ( int var_7 = 0 ;
    var_7 < var_5 . length ;
    var_7 += 2 * var_3 ) {
      int var_10 = var_7 , var_14 = Math . min ( var_7 + var_3 - 1 , var_5 . length - 1 ) ;
      while ( var_10 < var_14 ) {
        char var_15 = var_5 [ var_10 ] ;
        var_5 [ var_10 ++ ] = var_5 [ var_14 ] ;
        var_5 [ var_14 -- ] = var_15 ;
      }
    }
    return new String ( var_5 ) ;
  }
  