[Leetcode] Rorate Array by k steps

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]

Analysis:
This is a tricky question and is hard to come up with a neat solution at first glance.

Turns out the answer is pretty simple,  be careful about sanity check for value of k.

Solution:

void reverse(int *nums, int start, int end)
{
    if(start > end)
      return;
   
    int i = start, j = end;
    while(i < j)
    {
        int temp = nums[i];
        nums[i] = nums[j];
        nums[j] = temp;
        i++;
        j--;
    }
}

void rotate(int nums[], int n, int k) {
 
    k = k % n;                                 -> The sanity check is a bit tricky
    if(k>0 && k< n)                
    {
      // reverse whole thing first
      reverse(nums, 0, n -1);
 
     // reverse first k elements, then reverse the rest
      reverse(nums, 0, k-1);
      reverse(nums, k, n-1);
    }
}

Further thoughts:
Not much to say about question like this. Most ppl could finish it with hint.