First, clarify that the array contains only 0s and 1s and that we want all 0s before all 1s. Then, count the total number of 0s (or 1s) to determine the target partition, and use a two-pointer or sliding window technique to count misplaced elements, which directly gives the minimum swaps.
Pro tip: Mention that the minimum number of swaps equals the number of 1s in the first k positions (where k is the number of 0s), and that this can be computed in O(n) time and O(1) space. This shows you recognize the optimal solution and can articulate it clearly.
Confirm that the array contains only 0s and 1s, and that the goal is to sort it so all 0s come before all 1s. Ask if the array can be modified in-place or if a new array is needed.
Count the total number of 0s (or 1s) in the array. This count determines the size of the left partition that should contain all 0s.
Using a sliding window of size equal to the number of 0s, count how many 1s are in that window. Each 1 in the window is misplaced and needs to be swapped with a 0 outside the window.
The minimum number of swaps is exactly the number of 1s in the window (or equivalently, the number of 0s outside the window). Return that count.
State that the algorithm runs in O(n) time with a single pass to count zeros and another pass to count misplaced ones, and uses O(1) extra space.
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Finished the whole thing in maybe 10 minutes out of the hour they gave.
Start by thoroughly understanding the existing SpringBoot application structure and the two feature tasks, then prioritize based on complexity and dependencies. Implement incrementally with tests, ensuring each feature is working before moving to the next, and communicate your progress and trade-offs clearly.
Pro tip: Demonstrate Amazon's Leadership Principles by taking ownership of the tasks, diving deep into the code, and delivering results with high quality. Also, proactively mention how you would handle edge cases and scalability, showing customer obsession.
Read the task descriptions carefully and explore the existing SpringBoot project structure, including controllers, services, repositories, and models. Identify how the new features integrate with the current architecture.
Break down each feature into smaller sub-tasks, estimate effort, and decide the order of implementation based on dependencies and risk. Consider using a simple checklist to track progress.
Write code for the first feature, following SpringBoot best practices (e.g., layered architecture, dependency injection). Write unit and integration tests to validate functionality and catch regressions early.
After completing the first feature, review and refactor if needed, then move to the second feature. Continuously run tests and ensure the application remains stable.
Verbally explain your approach, decisions, and any trade-offs made during the process. Document key changes and how to run tests, demonstrating clarity and teamwork.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.
Not much detail I can share since I don't remember the exact prompt, but it was part of the same OA flow.
Start by clarifying the problem scope and requirements, then outline a high-level design before diving into details. Focus on scalability, reliability, and trade-offs, and be prepared to justify your choices with data and examples.
Pro tip: Amazon values customer obsession and ownership, so tie your design decisions back to customer impact and operational excellence. Also, explicitly discuss how you would measure success and iterate based on metrics.
Ask questions to understand functional and non-functional requirements, such as expected scale, latency, consistency, and availability needs. Confirm assumptions with the interviewer.
Sketch the main components (e.g., clients, APIs, services, databases, caches) and how they interact. Keep it abstract and focus on data flow.
Elaborate on critical components: data storage choices, partitioning, replication, load balancing, and caching. Discuss how to handle bottlenecks and failures.
Analyze trade-offs (e.g., SQL vs NoSQL, consistency vs availability) and explain how your design scales horizontally. Mention monitoring and metrics.
Summarize the design, reiterate how it meets requirements, and suggest potential improvements or next steps.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.