Merge Two Sorted Linked Lists — Algorithm interview question

Given two sorted singly linked lists, explain how you would merge them into a single sorted linked list.

For example:

List 1: 1 -> 3 -> 5
List 2: 2 -> 4 -> 6
Merged: 1 -> 2 -> 3 -> 4 -> 5 -> 6

How do you handle cases where the lists have different lengths? What about when one or both lists are empty?

Explain your approach and analyze the time and space complexity.

How to approach it

Hint 1
Compare the heads of both lists and pick the smaller value first.
Hint 2
Consider using a dummy head node to simplify the logic so you don't need special handling for the first element.
Hint 3
After one list is exhausted, append the remainder of the other list directly.

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