Given a singly linked list of size N. The task is to swap elements in the linked list pairwise.
For example, if the input list is 1 2 3 4, the resulting list after swaps will be 2 1 4 3.
Example 1:
Input:
LinkedList: 1->2->2->4->5->6->7->8
Output: 2 1 4 2 6 5 8 7
Explanation: After swapping each pair
considering (1,2), (2, 4), (5, 6).. so
on as pairs, we get 2, 1, 4, 2, 6, 5,
8, 7 as a new linked list.
Your Task:
The task is to complete the function pairWiseSwap() which takes the head node as the only argument and returns the modified head.
Expected Time Complexity: O(N). Expected Auxiliary Space: O(1).
