LeetCode:Rotate Array



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.

思路：

方法一：使用O(K)个空间，复杂度为O(n)，将后半段保存在数组中，然后将前半段后移，切记：是倒着移动！

方法二：使用O(N)个空间，复杂度为O(n)，将前后半段分别存储，代码略。

代码：

public:    void rotate(vector<int>& nums, int k) {    int n = nums.size();    if(k == 0)    {        return;    }    else if(k > 0)    {        k = k % n;        int array[k];        for(int i = n - k,j = 0; i < n; ++ i,++ j)            array[j] = nums[i];        for(int i = n - k -1,j = n - 1; i >= 0; --i,--j)            nums[j] = nums[i];        for(int i = 0,j = 0; i < k; ++i,++j)            nums[i] = array[j];    }    else    {        k = k % n ;  k = n + k;  int array[k];        for(int i = n - k,j = 0; i < n; ++ i,++ j)            array[j] = nums[i];        for(int i = n - k -1,j = n - 1; i >= 0; --i,--j)            nums[j] = nums[i];        for(int i = 0,j = 0; i < k; ++i,++j)            nums[i] = array[j];    }    }};</span>