Amazon·Software Engineer·Onsite - System Design / Architecture·Intermediate

Intermediate

Jul 2026

Summary

Amazon SWE interview with a system design question around building a package installer that handles dependency resolution. Pretty focused session, one meaty problem that required thinking through graph traversal and ordering.

Questions Asked (1)

Design a package installer system that resolves dependencies between packages and installs them in the correct order. For example, given a dependency map where pkgA depends on pkgB and pkgC depends on pkgA, the installer should output the correct installation sequence.

System DesignAlgorithms & Data StructuresTechnical Trade-offs

Author's notes

My first instinct was to treat it as a topological sort problem, which is basically right, but I fumbled explaining why for a bit.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and constraints, then model the dependencies as a directed graph and use topological sorting to determine installation order. Discuss handling cycles, parallel installations, and trade-offs between different algorithms and data structures.

Pro tip: Demonstrate awareness of real-world package managers by mentioning version constraints and conflict resolution, and discuss how to scale the solution for large dependency graphs.

1. Clarify Requirements and Constraints

Ask about the scale of the system, whether dependencies can have version constraints, and if parallel installation is needed. Confirm the expected output format and error handling for cycles.

2. Model Dependencies as a Graph

Represent packages as nodes and dependencies as directed edges. Explain that a topological sort will provide a valid installation order.

3. Choose Algorithm and Data Structures

Select between Kahn's algorithm (BFS-based) or DFS-based topological sort. Discuss using adjacency lists and in-degree counts for efficiency.

4. Handle Edge Cases and Optimizations

Address cycles (detect and report), parallel installation of independent packages, and incremental updates. Mention caching or memoization for repeated installs.

5. Discuss Trade-offs and Scalability

Compare time/space complexity of approaches, and discuss how to handle large graphs, distributed systems, and version resolution.

Key Points to Mention

Topological sorting algorithms (Kahn's and DFS-based) and their time/space complexity
Cycle detection and handling (e.g., reporting circular dependencies)
Parallel installation of independent packages to improve performance
Version constraints and conflict resolution (e.g., semantic versioning)
Scalability considerations for large dependency graphs (e.g., using distributed processing)
Real-world examples like apt, yum, or npm and how they handle dependencies

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