Bytedance·Software Engineer·Technical Phone Screen·Intermediate

IntermediatePrefer not to say

May 2026

Summary

Bytedance SWE interview with a parsing problem that looks straightforward until you actually have to handle edge cases. Stack-based approach, nested structures, the usual.

Questions Asked (1)

Given a string like '[1,[2,[3,4]],5]', parse it into the corresponding nested list structure.

Algorithms & Data Structures

Author's notes

I knew pretty quickly it was a stack problem.

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AI HintsAI Generated

Suggested Approach

Clarify the grammar and constraints, then propose a recursive descent parser or a stack-based iterative parser. Walk through the algorithm on the example, discussing time and space complexity and edge cases.

Pro tip: Mention that you would first define the grammar and handle edge cases like negative numbers and multi-digit integers, showing attention to detail. Also, discuss how to avoid deep recursion issues by considering an iterative approach.

1. Clarify requirements and constraints

Ask about input format, allowed characters, nesting depth, and expected output type. Confirm whether the string is always valid and if numbers can be negative or multi-digit.

2. Define the grammar and parsing strategy

Specify the grammar: a list is '[' elements ']' where elements are numbers or lists separated by commas. Choose between recursive descent and stack-based iterative parsing.

3. Implement the parser

For recursive descent, write a function that parses a value (number or list) and recursively parses lists. For iterative, use a stack to track current list and parse tokens.

4. Test with examples and edge cases

Walk through the given example and test edge cases like empty list, single element, deep nesting, and negative numbers. Verify correctness.

5. Analyze complexity and discuss optimizations

State time complexity O(n) and space O(d) for recursion depth or stack size. Mention potential optimizations like avoiding string concatenation or using an index pointer.

Key Points to Mention

Recursive descent parsing vs. stack-based iterative parsing
Handling multi-digit and negative numbers
Time and space complexity analysis
Edge cases: empty list, nested lists, whitespace
Avoiding deep recursion stack overflow
Using an index pointer to avoid string slicing overhead

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