Rotate String

Given a string and an offset, rotate string by offset. (rotate from left to right)

Example

Given "abcdefg".

offset=0 => "abcdefg"
offset=1 => "gabcdef"
offset=2 => "fgabcde"
offset=3 => "efgabcd"

分析：
利用 （A^TB^T）^T = BA

 public class Solution {
     /**
      * @param str: an array of char
      * @param offset: an integer
      * @return: nothing
      */
     public void rotateString(char[] str, int offset) {
         if (str == null || str.length <= ) return;
         offset = offset % str.length;
         if (offset == ) return;

         int p = str.length -  - offset;

         swapFromIToJ(str, , p);
         swapFromIToJ(str, p + , str.length - );
         swapFromIToJ(str, , str.length - );
     }

     public void swapFromIToJ(char[] str, int i, int j) {
         while (i < j) {
             char temp = str[i];
             str[i] = str[j];
             str[j] = temp;
             i++;
             j--;
         }
     }
 }