How do you merge two sorted linked lists into one sorted list?
This problem tests your ability to traverse and merge linked structures while maintaining order, a common task in sorting algorithms.
Why Interviewers Ask This
Interviewers ask this to verify your comfort with pointer manipulation and iterative merging techniques. It is a building block for more complex algorithms like Merge Sort. Efficiency and correctness in handling null pointers are key evaluation criteria.
How to Answer This Question
Propose a dummy head node to simplify edge cases. Iterate through both lists, comparing values and appending the smaller node to the result list. Continue until one list is exhausted, then append the remaining nodes of the other list. Analyze time complexity as O(m+n) where m and n are list lengths.
Key Points to Cover
- Use a dummy head node
- Compare and link nodes iteratively
- Append remaining nodes correctly
- Maintain O(m+n) time complexity
Sample Answer
I would create a dummy node to serve as the start of the merged list. Using two pointers, I would compare the current nodes of both lists and attach the smaller one to the result. After advancing the pointer of the chose…
Common Mistakes to Avoid
- Forgetting to handle null lists
- Incorrectly linking nodes
- Creating unnecessary new nodes
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