Interviewers ask this question to evaluate whether you can connect core data structures to real engineering constraints, not just recite definitions. A strong answer shows that you understand access patterns, complexity, memory trade-offs, and operational needs.
Describe one data structure you used in a real or hypothetical project and explain why you chose it.
Address these points:
The interviewer expects a concrete, engineering-focused explanation rather than a generic definition. Use one specific example, discuss the dominant read/write/query patterns, and justify the choice with complexity and practical constraints.