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.

Could you do it in-place with O(1) extra space?

要点: 数组中部分元素交换三次 (0, n-1), (0, k-1), (k-, n-1);

Edge cases: [1,2], k=4

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--;
        }
    }

    public void rotate(int[] nums, int k) {
        k = k % nums.length;
        reverse(nums, 0, nums.length-1);
        reverse(nums, 0, k-1);
        reverse(nums, k, nums.length-1);   
    }