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Bytedance·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
May 2026

Summary

Bytedance software engineer round with a linked list problem that sounds easy until you actually think about the constraints. One question, clean problem statement, two pointer trick required.

Questions Asked (1)

Q1

Given a singly linked list and its head pointer, return the value of the fifth node from the end. You must solve it in a single pass.

Algorithms & Data Structures
Author's notes

The one-pass constraint is the whole point.

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AI HintsAI Generated

Suggested Approach

Use the two-pointer technique: advance a fast pointer 5 nodes ahead, then move both pointers until the fast pointer reaches the end. The slow pointer will then be at the fifth node from the end. This achieves a single pass with O(n) time and O(1) space.

Pro tip: Clarify edge cases upfront, such as when the list has fewer than 5 nodes, and discuss how to handle them (e.g., return null or throw an exception). This shows attention to detail and robustness.

1. Understand the problem and constraints

Restate the problem to ensure clarity: find the value of the fifth node from the end in a singly linked list, in one pass. Confirm assumptions about list length and handling of edge cases.

2. Design the two-pointer approach

Initialize two pointers (slow and fast) at the head. Move the fast pointer 5 nodes ahead. If the list has fewer than 5 nodes, handle appropriately.

3. Traverse the list

Move both pointers one step at a time until the fast pointer reaches the end (null). The slow pointer will then point to the fifth node from the end.

4. Return the result

Return the value of the slow pointer. If the list is too short, return null or throw an exception as per requirements.

5. Analyze complexity and edge cases

State that time complexity is O(n) and space is O(1). Discuss edge cases: empty list, list with exactly 5 nodes, and list with fewer than 5 nodes.

Key Points to Mention

  • Two-pointer technique (slow and fast pointers)
  • Single pass requirement and how it's achieved
  • Time complexity O(n) and space complexity O(1)
  • Handling edge cases: list length < 5, empty list
  • Difference between returning the node vs. the value
  • Potential follow-up: generalize to k-th node from end

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