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.

[show hint]

Related problem: Reverse Words 
 
in a String II

三步翻轉法, 同 Recover Rotated Sorted Array , 註意反轉順序和k範圍.

如果:

reverse(nums, 0, k);
reverse(nums, k + 1, len-1);
reverse(nums, 0, len-1);

則:

public void rotate(int[] nums, int k) {
        int len = nums.length;
        k %= len;
        reverse(nums, 0, len-1);
        reverse(nums, 0, k-1);
        reverse(nums, k, len-1);
    }
    
    public void reverse(int[] nums, int l, int r) {
        while (l <= r) {
            int temp = nums[l];
            nums[l] = nums[r];
            nums[r] = temp;
            l++;
            r--;
        }
    }

189. Rotate Array