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Amazon·Software Engineer·Online Assessment (OA)·Junior

JuniorPending
Jun 2026Europe

Summary

Sat the Amazon OA for an SDE I role in Europe and it was a mess from start to finish. The DSA section threw a genuinely hard DP problem at me, and the AI-assisted coding section had a broken AI tool the whole time.

Questions Asked (2)

Q1

String manipulation problem involving merging branches with conflicts.

Algorithms & Data Structures
Author's notes

Went with two pointers, felt reasonable at the time.

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AI HintsAI Generated

Suggested Approach

Clarify the problem by defining what 'merging branches with conflicts' means in string terms, then propose a two-pointer or stack-based approach to identify and resolve conflicts. Walk through a concrete example, discuss time/space complexity, and handle edge cases like empty strings or multiple conflicts.

Pro tip: Demonstrate Amazon Leadership Principles by proactively discussing trade-offs (e.g., time vs. space) and asking clarifying questions about conflict resolution rules before coding.

1. Clarify the Problem

Ask questions to understand the input format, conflict markers, and expected output. Confirm whether conflicts are resolved by choosing one branch or merging characters.

2. Define Conflict Resolution Rules

Establish clear rules for resolving conflicts, such as preferring the first branch, concatenating, or using a priority. This ensures a deterministic solution.

3. Choose Data Structures & Algorithm

Select an efficient approach, e.g., two pointers for linear scan or a stack for nested conflicts. Explain why it's optimal for the given constraints.

4. Walk Through an Example

Trace the algorithm on a sample input, highlighting how conflicts are detected and resolved step by step.

5. Analyze Complexity & Edge Cases

State time and space complexity, and discuss edge cases like empty strings, no conflicts, or all conflicts.

Key Points to Mention

  • Two-pointer technique for linear time complexity
  • Stack-based approach for handling nested or multiple conflicts
  • Conflict resolution strategy (e.g., prefer first branch, merge characters)
  • Time and space complexity analysis (O(n) time, O(1) or O(n) space)
  • Edge cases: empty strings, no conflicts, all conflicts
  • Amazon Leadership Principles: Customer Obsession (clarify requirements), Dive Deep (analyze edge cases)

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

Q2

Debug a Spring Boot repository with multiple bugs introduced into the codebase.

Root Cause AnalysisAPI & Integrations
Author's notes

This was supposed to be AI-assisted but the AI tool on the platform errored out every single time I tried to use it.

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AI HintsAI Generated

Suggested Approach

Start by reproducing the bugs with tests or manual calls, then systematically isolate each issue using logs, debugger, and code inspection. Prioritize fixes based on impact and verify each fix with automated tests to prevent regressions.

Pro tip: Demonstrate a methodical approach by first writing a failing test for each bug before fixing it—this shows you value test-driven debugging and ensures the fix is correct. Also, mention that you'd check for common Spring Boot pitfalls like misconfigured beans, transaction boundaries, and improper exception handling.

1. Reproduce and Document Bugs

Run the application and execute test cases to reproduce each bug. Document the symptoms, error messages, and stack traces for each issue.

2. Isolate Root Causes

Use debugging tools, logging, and code review to trace each bug to its source. Check for common Spring Boot issues like incorrect annotations, dependency injection problems, or misconfigured properties.

3. Prioritize and Fix

Rank bugs by severity and fix them one by one, ensuring each fix is minimal and targeted. Write unit or integration tests to confirm the fix and prevent regressions.

4. Verify and Validate

Run the full test suite and perform manual testing to ensure all bugs are resolved and no new issues are introduced. Validate that the application meets the original requirements.

5. Reflect and Prevent

Summarize the root causes and suggest improvements to prevent similar bugs, such as better test coverage, code reviews, or static analysis tools.

Key Points to Mention

  • Use of Spring Boot testing annotations like @SpringBootTest, @DataJpaTest, and @WebMvcTest to isolate layers.
  • Common Spring Boot pitfalls: misconfigured application.properties, incorrect bean scopes, missing @Transactional, and improper exception handling.
  • Debugging tools: IDE debugger, logging frameworks (SLF4J, Logback), and Spring Boot Actuator for runtime insights.
  • Importance of writing failing tests first to confirm the bug and then passing tests after the fix.
  • Root cause analysis techniques like the 5 Whys or fishbone diagram to systematically identify underlying issues.
  • Communication: explaining the debugging process clearly and documenting findings for the team.

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