Rotate Array

Rotate an array of n elements to the right by k steps.

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].

Note:

Try to come up as many solutions as you can, there are at least 3 different ways to solve this problem.

Hint:

Could you do it in-place with O(1) extra space?
Related problem: Reverse Words in a String II

Solution:

  1. public class Solution {
  2.   public void rotate(int[] nums, int k) {
  3.     int n = nums.length;
  5.     k %= n;
  7.     reverse(nums, 0, n - k - 1);
  8.     reverse(nums, n - k, n - 1);
  9.     reverse(nums, 0, n - 1);
  10.   }
  12.   private void reverse(int[] nums, int i, int j) {
  13.     while (i < j) {
  14.       int val = nums[i];
  15.       nums[i++] = nums[j];
  16.       nums[j--] = val;
  17.     }
  18.   }
  19. }