07/16/2016 Array

## Question

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?

## Solution

Result: Accepted Time: 24 ms

Here should be some explanations.

class Solution {
void reverse(vector<int>& nums,int i,int k)
{
int tmp ;
while(i<k)
{
tmp = nums[i];
nums[i++] = nums[k];
nums[k--] = tmp;
}

}
public:
void rotate(vector<int>& nums, int k) {
k = k%(nums.size());
if(!k) return ;
reverse(nums,0,nums.size()-k-1);
reverse(nums,nums.size()-k,nums.size()-1);
reverse(nums,0,nums.size()-1);
}
};


Complexity Analytics

• Time Complexity: $O(n)$
• Space Complexity: $O(1)$