This is another difficult linked list algorithm question which is mostly asked to experienced programmers e.g. programmer having 3 to 6 years of experience. You have been given a singly linked list and you need to write a function to reverse every alternate k nodes (where k is an input to the function) in an efficient way. You also need to calculate the time and space COMPLEXITY of your algorithm.

Example:

INPUTS: 1->2->3->4->5->6->7->8->9->NULL and k = 3

Output: 3->2->1->4->5->6->9->8->7->NULL.

This is another difficult linked list algorithm question which is mostly asked to experienced programmers e.g. programmer having 3 to 6 years of experience. You have been given a singly linked list and you need to write a function to reverse every alternate k nodes (where k is an input to the function) in an efficient way. You also need to calculate the time and space complexity of your algorithm.

Example:

Inputs: 1->2->3->4->5->6->7->8->9->NULL and k = 3

Output: 3->2->1->4->5->6->9->8->7->NULL.