循环移k位，3个reverse完成

LeetCode189. Rotate Array

class Solution {public:    void rotate(vector<int>& nums, int k) {        int n = nums.size();        k = k % n;        reverse(nums.begin(), nums.begin() + n - k);        reverse(nums.begin() + n - k, nums.begin() + n);        reverse(nums.begin(), nums.begin() + n);    }};