class Solution {
public:
    void myReverse(vector<int> &nums,int start, int end)   {
        while(start < end)  {
            swap(nums[start++], nums[end--]);
        }
    }
    void rotate(vector<int>& nums, int k) {
        if(nums.size()<2)   return;
        k = k % nums.size();
        myReverse(nums, 0, nums.size() - k - 1);
        myReverse(nums, nums.size()-k, nums.size() - 1);
        myReverse(nums, 0 , nums.size() - 1);
    }
};