LeetCode No.189 Rotate Array

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.

[show hint]

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

Related problem: Reverse Words in a String II

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题目链接：https://leetcode.com/problems/rotate-array/
题目大意：将给定数组右移k位。（使用O(1)的空间复杂度）
思路：当k整除n的时候，其实就是它本身，再将k对n取模。因为要使用O(1)的空间复杂度，所以我们要想个办法直接对数组进行操作。

具体操作如下：

前半部分反转，后半部分反转，再整体反转。

附上代码：

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