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>