0189.md

• 这就是 std::rotate 的功能，它可以交换两个区间范围内的元素

class Solution {
 public:
  void rotate(vector<int>& nums, int k) {
    std::rotate(rbegin(nums), rbegin(nums) + k % size(nums), rend(nums));
  }
};

• 原理是三次翻转

1234 567 => 目标 567 1234
765 4321
567 1234

• 实现如下

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