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Workday·Software Engineer·Technical Phone Screen·Senior

Senior
Jun 2026

Summary

Workday SWE interview that was basically one meaty coding problem with a follow-up that caught me off guard. The core question was manageable but the fuzzy matching extension is where things got interesting and honestly a bit painful.

Questions Asked (2)

Q1

Design a class that takes a body of text at construction time and supports a query method that returns all 0-indexed starting positions where a given keyword appears in the text.

Algorithms & Data StructuresSystem Design
Author's notes

The straightforward part.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements: case sensitivity, overlapping matches, and whether the text is static. Then propose a class that preprocesses the text (e.g., builds a suffix array or trie) to enable efficient queries, and discuss trade-offs between preprocessing time and query time.

Pro tip: Mention that for a static text, you can preprocess to answer queries in O(m + k) time using a suffix automaton or suffix array with binary search, which is optimal. Also, clarify if the keyword can be empty or if matches should be case-insensitive.

1. Clarify requirements

Ask about case sensitivity, overlapping matches, expected query frequency, and text size to determine the best approach.

2. Choose data structure

Decide between simple string search (O(n*m) per query) or preprocessing (e.g., suffix array, suffix automaton, trie) for faster queries.

3. Design class interface

Define constructor that takes text and builds the chosen data structure, and a query method that returns a list of starting indices.

4. Implement query method

For preprocessing approach, use the data structure to find all occurrences efficiently; for simple approach, use a string search algorithm like KMP.

5. Analyze complexity and trade-offs

Discuss time and space complexity of construction and query, and justify the choice based on expected usage.

Key Points to Mention

  • Case sensitivity and overlapping matches handling
  • Preprocessing vs. on-the-fly search trade-offs
  • Suffix array or suffix automaton for efficient substring search
  • Time complexity: O(n) preprocessing, O(m + k) query where k is number of matches
  • Space complexity of the chosen data structure
  • Edge cases: empty keyword, keyword longer than text, no matches

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

Q2

Extend the query method to also return positions where the text matches the keyword with at most one edit (insertion, deletion, or substitution).

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

This is where I started sweating.

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AI HintsAI Generated

Suggested Approach

Clarify the current query method's behavior and constraints, then propose extending it using an edit-distance-aware search such as Levenshtein automaton or dynamic programming with early termination. Discuss trade-offs between preprocessing, time/space complexity, and practical implementation for the given scale.

Pro tip: Mention that you would first check if the existing query method can be augmented with a bounded edit distance filter, and consider using a trie or BK-tree if multiple queries are expected, showing awareness of real-world performance beyond the naive approach.

1. Clarify requirements and constraints

Ask about the expected input size, query frequency, allowed edits (only one), and whether the text is static or dynamic. This determines the appropriate algorithm and data structure.

2. Choose an algorithm for approximate matching

Select a method like dynamic programming (Levenshtein distance with early exit), Levenshtein automaton, or trie-based search that efficiently finds matches within edit distance 1.

3. Integrate with existing query method

Modify the query method to iterate over candidate positions or use an index, applying the edit distance check and collecting positions where distance ≤ 1.

4. Analyze complexity and trade-offs

Compare time and space complexity of the chosen approach versus alternatives, and discuss when preprocessing (e.g., building an index) is beneficial.

5. Test and handle edge cases

Consider empty strings, keyword longer than text, multiple matches, and overlapping edits. Write unit tests to validate correctness.

Key Points to Mention

  • Levenshtein distance and how to compute it with at most one edit efficiently
  • Early termination in dynamic programming when distance exceeds 1
  • Use of data structures like trie or BK-tree for multiple queries
  • Time complexity: O(n*m) naive vs. optimized approaches
  • Space complexity and potential preprocessing costs
  • Edge cases: empty keyword, keyword longer than text, case sensitivity

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