Merging Two Sorted Linked Lists Using Iterative Method in Python

Problem Explanation You are given two sorted linked lists list1 and list2 . Your task is to merge them into a single sorted linked list . The new list should be created by reusing the existing nodes . Example: Input: list1 = [1,2,4] , list2 = [1,3,4] Output: [1,1,2,3,4,4] Input: list1 = [] , list2 = [] Output: [] Method Used: Iterative Approach (Two Pointer Technique) Idea Compare nodes from both lists Pick the smaller one Move forward Repeat until one list ends Why This Method? Time complexity: O(n + m) Space complexity: O(1) Efficient and easy to implement No extra memory required Python Code with Explanation class Solution : def mergeTwoLists ( self , list1 , list2 ): Defines the function. dummy = ListNode ( 0 ) Create a dummy node to simplify merging. tail = dummy tail will build the merged list. while list1 and list2 : Loop until one list becomes empty. if list1 . val < list2 . val : Compare values of both lists. tail . next = list1 list1 = list1 . next Attach smaller node from li