RotateArray.java

package array;

/**
 * Created by gouthamvidyapradhan on 01/08/2017. Rotate an array of n elements to the right by k
 * steps.
 *
 * <p>For example, with n = 7 and k = 3, the array [1,2,3,4,5,6,7] is rotated to [5,6,7,1,2,3,4].
 *
 * <p>Note: Try to come up as many solutions as you can, there are at least 3 different ways to
 * solve this problem.
 *
 * <p>Hint: Could you do it in-place with O(1) extra space? Related problem: Reverse Words in a
 * String II
 */
public class RotateArray {
  /**
   * Main method
   *
   * @param args
   * @throws Exception
   */
  public static void main(String[] args) throws Exception {
    int[] A = {1, 2, 3, 4, 5, 6};
    new RotateArray().rotate(A, 2);
    for (int i : A) System.out.print(i + " ");
  }

  public void rotate(int[] nums, int k) {
    k = k % nums.length;
    reverse(nums, 0, nums.length - 1);
    reverse(nums, 0, k - 1);
    reverse(nums, k, nums.length - 1);
  }

  private void reverse(int[] nums, int s, int e) {
    for (int i = s, j = e; i < j; i++, j--) {
      int temp = nums[i];
      nums[i] = nums[j];
      nums[j] = temp;
    }
  }
}