Problem:
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.

• 使用两次翻转即可，第一次以k分割线翻转[4,3,2,1,7,6,5]，第二次全部翻转[5,6,7,1,2,3,4]