Explain hash maps and solve array intersection
Company: Citadel
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: Medium
Interview Round: Take-home Project
Quick Answer: This question evaluates a candidate's understanding of hash map internals — including array/bucket layout, hash function selection, collision resolution strategies, load factor and resizing behavior, deletion semantics, time-space trade-offs — alongside algorithmic problem-solving for computing intersections across k integer arrays and the generalization to elements appearing in at least t arrays, with attention to duplicates and edge cases. It is commonly asked to assess mastery of core data structures, algorithm design and complexity analysis within the Coding & Algorithms domain, testing both conceptual understanding of data-structure internals and practical application of algorithmic reasoning and performance trade-offs.