Related Coding / DSA
Longest Run of Non-Repeating Characters
Given a string, find the length of the longest contiguous substring in which no character repeats.
1. Problem Statement
You are given a dictionary of words. Build a structure supporting countWithPrefix(prefix), which returns how many dictionary words start with the given prefix. Multiple prefix queries will be made against the same dictionary.
2. Live Coding Format
Work in the provided coding workspace while explaining your decisions to the live interviewer. Validation may use inline tests, examples, comments, or a verbal walkthrough.
3. Key Focus Areas
- 1Problem clarification and contract
- 2Approach exploration and optimality
- 3Think-aloud communication and pacing
- 4Implementation correctness
- 5Code quality and language fluency
- 6Handwritten tests and dry run
- 7Debugging and self-correction
- 8Complexity analysis
- 9Follow-up performance
4. What Strong Candidates Should Demonstrate
- ✓Clarify character set, duplicate words, and empty-prefix behavior before coding.
- ✓Explain a naive per-query full-scan baseline and improve to a trie with per-node word counts.
- ✓Think aloud while implementing careful trie construction and traversal.
- ✓Validate with explicit expected outputs and a top-to-bottom handwritten dry run.
- ✓Analyze time and space complexity and handle a bounded follow-up modification.
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Practice this problem in the live coding workspace while the interviewer probes your clarification, implementation, trade-offs, and validation.
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