### 问题描述

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.

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

### 代码

class Solution {
public:
void rotate(vector<int>& nums, int k) {
int n = nums.size();
if(k>n) k=k%n;
// 翻转整个数组
reverse(nums, 0, n-1);
// 翻转 0:k-1
reverse(nums, 0, k-1);
// 翻转 k:n-1
reverse(nums, k, n-1);
}

void reverse(vector<int>& nums, int i, int j) {
while(i<j) {
int t = nums[i];
nums[i] = nums[j];
nums[j] = t;
i++,j--;
}
}
};