Oracle·Software Engineer·Technical Phone Screen·Intermediate

Intermediate

May 2026

Summary

Oracle SWE interview, just one coding question about merging two sorted linked lists. Pretty standard stuff, nothing too wild.

Questions Asked (1)

Given two sorted linked lists, merge them into a single sorted linked list.

Algorithms & Data Structures

Author's notes

Classic problem and I still fumbled the pointer logic the first time through.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the problem constraints and edge cases, then propose an iterative two-pointer approach that merges the lists in O(n+m) time and O(1) space. Walk through the algorithm step-by-step, and if time permits, discuss alternative solutions like recursion and their trade-offs.

Pro tip: Demonstrate awareness of production concerns by mentioning that you would handle null inputs gracefully and consider whether modifying the input lists is acceptable, as this shows maturity beyond just solving the algorithm.

1. Clarify requirements and edge cases

Ask about input constraints (e.g., can lists be empty? are they singly or doubly linked? can we modify inputs?) and confirm expected output format. This ensures you understand the problem fully before coding.

2. Outline the two-pointer approach

Explain that you'll use two pointers, one for each list, and a dummy node to build the merged list. Compare the current nodes and append the smaller one to the result, advancing that pointer.

3. Walk through the algorithm with an example

Trace the algorithm on a small example (e.g., 1->3->5 and 2->4->6) to demonstrate correctness and clarify pointer manipulation. This helps catch off-by-one errors early.

4. Analyze complexity and discuss trade-offs

State that the iterative solution runs in O(n+m) time and O(1) space. Mention that a recursive solution is also possible but uses O(n+m) stack space, so iterative is preferred for large lists.

5. Handle edge cases and conclude

Explain how to handle empty lists, lists of different lengths, and duplicate values. Summarize that the dummy node simplifies edge cases and the solution is optimal.

Key Points to Mention

Use a dummy node to simplify edge cases and avoid special handling for the head of the merged list.
Maintain two pointers to traverse the input lists, comparing values and advancing the pointer of the smaller node.
Time complexity is O(n+m) and space complexity is O(1) for the iterative approach.
Recursive solution is elegant but uses O(n+m) stack space, which may cause stack overflow for large lists.
Handle edge cases: one or both lists empty, lists of unequal length, and duplicate values.
Clarify whether the input lists can be modified; if not, create new nodes instead of rearranging pointers.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.