Reverse a Linked List in Pairs

Given a singly-linked list, reverse the list in pairs.

Example:
Given 1->2->3->4,
reverseInPairs(1) ==> 2->1->4->3

Need a hand? Try out these hints, one at a time.

The key here is to traverse through the List, two nodes at a time and swap the data between adjacent nodes.

1. Create a pointer for the head node.

2. While the current node curr and next are not null, traverse the List

3. Swap the data between the two nodes.

4. Increment the pointers by two nodes to fetch next pair.

public ListNode reverseInPairs(ListNode head) {
        





    
}

Java

Python