/* Design an algorithm to rotate an array/string to the right by k positions

* http://blog.csdn.net/v_july_v/article/details/6322882

*/

public class RotateArray {

public static void main(String[] args) {

char[] arr = {'a', 'b', 'c', 'd', '1', '2', '3', '4'};

int k = 3;

System.out.println("Before: " + new String(arr));

rotate(arr, k);

System.out.println("After: " + new String(arr));

}

public static void rotate(char[] arr, int k) {

k %= arr.length;

reverse(arr, 0, arr.length-1);

reverse(arr, 0, k-1);

reverse(arr, k, arr.length-1);

}

public static void reverse(char[] arr, int left, int right) {

while(left < right) {

char tmp = arr[left];

arr[left] = arr[right];

arr[right] = tmp;

left++;

right--;

}

}

}