Given an array, rotate the array to the right by k steps, where k is non-negative.

Follow up:

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?

Example 1:

Input: nums = [1,2,3,4,5,6,7], k = 3
Output: [5,6,7,1,2,3,4]
Explanation:
rotate 1 steps to the right: [7,1,2,3,4,5,6]
rotate 2 steps to the right: [6,7,1,2,3,4,5]
rotate 3 steps to the right: [5,6,7,1,2,3,4]

Example 2:

Input: nums = [-1,-100,3,99], k = 2
Output: [3,99,-1,-100]
Explanation: 
rotate 1 steps to the right: [99,-1,-100,3]
rotate 2 steps to the right: [3,99,-1,-100]

Constraints:

1 <= nums.length <= 2 * 104
-231 <= nums[i] <= 231 - 1
0 <= k <= 105

Solution

Time complexity : O(n)
Space complexity : O(1)

class Solution {
public:
    void rotate(vector<int>& nums, int k) {
        if (nums.empty()) return;
        k %= nums.size();
        if (0 == k) return;
        reverse(nums.begin(), nums.end());
        reverse(nums.begin(), nums.begin()+k);
        reverse(nums.begin()+k, nums.end());
    }
};