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? Credits: Special thanks to @Freezen for adding this problem and creating all test cases.

1. reverse all array
2. reverse first k
3. reverse remaining