Rotate Array

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:
  • Space Complexity: