Jryntorica Qysalind 
If you’re applying for a software engineering role at Amazon, you’ll likely encounter Online Assessments (OAs) as part of the hiring process. Among these, OA2 (Online Assessment 2) is a critical step that tests your coding skills with LeetCode-style problems.
In this blog, we’ll break down:
l What OA means in Amazon’s hiring process
l The differences between OA1, OA2, and OA3
l Whether Amazon OA2 is difficult
l How to prepare effectively to pass this round
Let’s dive in!
What Does Amazon OA?
OA stands for Online Assessment, a series of tests Amazon uses to evaluate candidates before moving them to the final interview rounds. The process typically consists of three stages:
l OA1 – Debugging and reasoning
l OA2 – Coding challenges (LeetCode-style)
l OA3 – Work simulation and behavioral assessment
Each stage filters candidates based on different skills, with OA2 being the most technical.
Amazon OA1, OA2, and OA3 Breakdown
1. OA1 – Debugging & Reasoning
– Format: 20-30 debugging and logical reasoning questions
– Debugging Section: Fix bugs in given code snippets (usually in C++, Java, or Python)
– Reasoning Section: Aptitude questions (similar to IQ tests or basic math/logic problems)
– Time Limit: ~30-45 minutes
– Difficulty: Generally easy if you’re comfortable with basic coding
2. OA2 – LeetCode-Style Coding Questions (Focus of This Guide)
– Format: 2 coding problems (medium to hard difficulty)
– Topics: Arrays, strings, trees, graphs, dynamic programming (DP), and more
– Time Limit: 60-90 minutes
– Evaluation Criteria:
– Correctness (passing all test cases)
– Optimality (time and space complexity)
– Code readability and structure
This round is the most challenging for many candidates because it requires strong problem-solving skills under time pressure.
3. OA3 – Work Simulation & Behavioral Assessment
– No coding questions
– Work Simulation: Simulates real Amazon work scenarios (e.g., prioritizing tasks, system design discussions)
– Behavioral Questions: Based on Amazon’s Leadership Principles
– Time Limit: ~3 hours (but not as intense as OA2)
Is Amazon OA2 Difficult?
The difficulty of OA2 depends on your preparation. Here’s what makes it challenging:
Medium-to-Hard LeetCode Problems – Expect questions similar to LeetCode Medium/Hard (e.g., DFS/BFS, DP, sliding window).
Time Pressure – You have 30-45 minutes per question, so speed matters.
Optimal Solutions Required – Brute-force solutions may fail hidden test cases.
However, if you’ve practiced Amazon-tagged LeetCode questions, you’ll find many problems that are familiar.
How to Prepare for Amazon OA2
1. Master Key LeetCode Topics
Focus on:
– Arrays & Strings (sliding window, two-pointer)
– Trees & Graphs (DFS, BFS, topological sort)
– Dynamic Programming (memoization, tabulation)
– Heap & Priority Queues (useful for optimization problems)
2. Practice Amazon-Tagged Questions
– Filter LeetCode’s Amazon-tagged problems [here](https://leetcode.com/company/amazon/).
– Solve at least 50-100 problems before the test.
3. Simulate Real Test Conditions
– Use a timer (30-45 mins per question).
– Write code in LeetCode’s environment (no IDE help).
– Test edge cases manually.
4. Optimize Your Approach
– Brute-force first, then optimize.
– Explain your thought process (interviewers may review your code).
– Ensure O(n) or O(n log n) solutions for most problems.
Final Tips for Success
Understand Amazon’s Leadership Principles – Even in OA2, clean and efficient code reflects Ownership and Customer Obsession.
Write Readable Code – Use proper variable names and comments.
Test Thoroughly – Check edge cases (empty input, large inputs).
Stay Calm Under Pressure – If stuck, try a different approach.
Conclusion
Amazon OA2 is a LeetCode-style coding round that tests your problem-solving skills with medium-to-hard questions. While it’s challenging, consistent practice and optimal solutions will help you pass. ProgramHelp encourages you to check recommended LeetCode problems, join coding communities, and practice regularly to boost your chances of securing an offer.
Next Steps
– Start practicing Amazon-tagged LeetCode problems.
– Join coding communities (e.g., LeetCode Discuss, Blind 75).
– Mock interviews will simulate real test conditions.
Good luck, and happy coding!
Need more help? Check out:
– [Amazon OA2 LeetCode Questions List](https://leetcode.com/company/amazon/)
– [Top 50 Amazon Coding Questions](https://programhelp.net/amazon-oa2-work-simulation/) (placeholder)
