189. 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.

 

class Solution {

    public void rotate(int[] nums, int k) {

       k = k % nums.length;

       reverse(nums, 0, nums.length - 1); //先整体倒置

       reverse(nums, 0, k - 1); //前k个倒置

       reverse(nums, k, nums.length - 1); //剩余的倒置

   }

   

    private void reverse(int[] nums, int start, int end) {

       while (start < end) {

          int temp = nums[start];

          nums[start] = nums[end];

          nums[end] = temp;

          start++;

          end--;

       }

    }    

}