Rotate String

 1 public class Solution {
 2     /**
 3      * @param str: an array of char
 4      * @param offset: an integer
 5      * @return: nothing
 6      */
 7     public static char[] rotateString(char[] str, int offset) {
 8         if (str == null || str.length == 0){
 9             return str;
10         }
11         int len = str.length;
12         offset %= len;
13         reverse(str, 0, len - offset - 1);
14         reverse(str, len - offset, len - 1);
15         reverse(str, 0, len - 1);
16         return str;
17     }
18     public static void reverse(char[] str, int start, int end){
19         while (start < end){
20             char temp = str[start];
21             str[start] = str[end];
22             str[end] = temp;
23             start++;
24             end--;
25         }
26     }
27 }