题目

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?

思路一

跟字符串左右旋转操作一样的思路。
三次翻转法，第一次翻转前n-k个，第二次翻转后k个，第三次翻转全部。

代码一

    /*--------------------------------------------
    *   日期：2014-02-25
    *   作者：SJF0115
    *   题目: 189.Rotate Array
    *   网址：https://oj.leetcode.com/problems/rotate-array/
    *   结果：AC
    *   来源：LeetCode
    *   博客：
    ------------------------------------------------*/
    #include 
   
     #include 
    
      using namespace std; class Solution { public: void rotate(int nums[], int n, int k) { if(n <= 1){ return; }//if k = k % n; if(k <= 0){ return; }//if // 翻转前n-k个 Reverse(nums,0,n - k - 1); // 翻转后k个 Reverse(nums,n - k,n - 1); // 翻转全部 Reverse(nums,0,n - 1); } private: void Reverse(int nums[],int left,int right){ int tmp; for(int i = left,j = right;i < j;++i,--j){ // 交换 swap(nums[i],nums[j]); }//for } }; int main() { Solution solution; int A[] = {1,2,3,4,5,6,7}; int n = 7; int k = 2; solution.rotate(A,n,k); for(int i = 0;i < n;++i){ cout<