[leetcode] Rotate Array

Rotate Array

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.

Credits:
Special thanks to @Freezen for adding this problem and creating all test cases.

 

空间复杂度为O(1)。

 

class Solution
{
public:
  void rotate(int nums[], int n, int k)
  {
    if(k == 0 || k == n)
      return;

    if(k > n)
      k = k - n;

    int m = 0;
    for(int i=0; i<k; i++)
    {
      m = nums[n-i-1];
      for(int j=n-i-1; j>=0;)
      {
        if(j-k >= 0)
          nums[j] = nums[j-k];
        else
          nums[j] = m;

        j -= k;
      }
    }

    int len = n % k;
    if(len != 0)
      rotate(nums, k, k - len);
  }
};