24. Swap Nodes in Pairs

Level: Meduim
Link: https://leetcode.com/problems/swap-nodes-in-pairs/

Problem

Given a linked list, swap every two adjacent nodes and return its head.

You may not modify the values in the list's nodes, only nodes itself may be changed.

Example:

Given 1->2->3->4, you should return the list as 2->1->4->3.

Solution

• Approach 1: Recursive Approach
• Approach 2: Iterative Approach