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Citadel·Software Engineer·Technical Phone Screen·Junior

JuniorRejected
Oct 2026Remote

Summary

Did two rounds for a Citadel SWE intern position and got rejected before the super day, which stings. First round was an OOD question that went sideways pretty fast, second was an AI-assisted coding round that actually felt great. Disappointing result overall, especially as a Canadian trying to break into the US market.

Questions Asked (2)

Q1

Design an object-oriented system for a given problem, and implement the solution.

System DesignTechnical Trade-offs
Author's notes

This one was rough before I even typed a line.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the problem requirements and constraints, then identify the core entities and their relationships. Design the class hierarchy using appropriate design patterns, and implement a clean, extensible solution while discussing trade-offs.

Pro tip: At Citadel, interviewers value code quality and performance. Before coding, briefly outline your design and ask if the interviewer prefers a particular pattern or has any constraints, showing collaboration and foresight.

1. Clarify Requirements

Ask questions to understand functional and non-functional requirements, such as expected scale, performance needs, and any specific features. This ensures you design the right system.

2. Identify Core Entities

Determine the main objects, their attributes, and behaviors. Define relationships like inheritance, composition, and associations.

3. Design Class Structure

Apply SOLID principles and design patterns (e.g., Factory, Strategy, Observer) to create a flexible and maintainable class diagram. Consider interfaces and abstract classes.

4. Implement the Solution

Write clean, modular code with meaningful names and comments. Focus on correctness and extensibility, and handle edge cases.

5. Discuss Trade-offs and Extensions

Explain why you chose certain patterns, discuss alternative approaches, and suggest how the design could scale or adapt to new requirements.

Key Points to Mention

  • SOLID principles and how they apply to the design
  • Design patterns used (e.g., Factory, Singleton, Observer) and their benefits
  • Encapsulation, inheritance, and polymorphism in the class hierarchy
  • Handling concurrency and thread-safety if relevant to the problem
  • Performance considerations and time/space complexity of key operations
  • Extensibility and maintainability of the design

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

Q2

Solve a coding problem (algorithmic), then discuss its trade-offs, optimizations, and alternative approaches.

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

Got the solution coded up fully, which felt good.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the problem and constraints, then walk through a brute-force solution before optimizing. Implement the optimal solution with clean code, test with edge cases, and discuss trade-offs, optimizations, and alternatives.

Pro tip: At Citadel, interviewers value not just correct solutions but also the ability to articulate trade-offs and think about scalability. Always quantify time/space complexity and relate it to real-world performance.

1. Understand and Clarify

Ask clarifying questions to confirm input/output formats, constraints, and edge cases. Restate the problem in your own words to ensure alignment.

2. Explore Approaches

Discuss a brute-force solution first, then propose optimizations. Compare time and space complexity of each approach.

3. Implement and Test

Write clean, modular code for the chosen approach. Walk through test cases, including edge cases, to verify correctness.

4. Analyze Trade-offs

Explain the trade-offs between different solutions (e.g., time vs. space, readability vs. performance). Discuss potential optimizations and alternative algorithms.

5. Reflect and Extend

Consider how the solution would scale with larger inputs or distributed systems. Mention any relevant real-world applications or further optimizations.

Key Points to Mention

  • Time and space complexity analysis (Big O notation)
  • Trade-offs between different data structures (e.g., hash maps vs. arrays)
  • Edge cases and input validation
  • Code readability and maintainability
  • Potential optimizations (e.g., caching, parallelization)
  • Alternative algorithms and their applicability

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