Many people think Amazon a VO interview is just about grinding problems, but from real experience, coding, Leadership Principles, and project deep dives are almost tested in parallel. If any part is not prepared enough, the interview can easily go badly.
My timeline this time was fairly typical:
Applied in February
Received the OA in March
Entered the VO stage in April
Completed the interview in late April
Passed successfully afterward
At that time, I also had other interviews and had to balance coursework and projects, so my preparation time was very fragmented. To be honest, I was quite anxious in the early stage of VO preparation: my LP stories were not fully organized, my coding state was average, and I often had pacing issues during mock interviews. With Programhelp's support, I gradually brought the preparation rhythm back on track. The final result was good, and I passed the VO successfully. Looking back, beyond basic preparation, interview pacing and on-the-spot performance were really important.
Below, I will go through the real process, questions, and pitfalls from this Amazon VO in late April.
First round
The interviewer was a white male engineer, and he asked very deeply about my Redis caching project:
- Why did you introduce caching in the project?
- How did you handle cache penetration, cache avalanche, and cache consistency?
- Follow-upFor write operations, should you delete the cache first or update the database first? What problems does each approach have? How would you implement delayed double deletion?
I explained the causes and solutions for the three cache-related issues clearly using my real project experience, and the interviewer seemed satisfied.
Coding section:
Length of the longest palindromic substring
TopicGiven a string, find the length of the longest palindromic substring.
IdeasUse the center expansion method, with O(n²) time and O(1) space.
Follow-upIf the string length reaches 10^5, center expansion will time out. How would you optimize it? I answered with MManacher's algorithm, which can achieve O(n) time, and briefly explained the idea of trading space for time.
Minimum number of palindrome partitions
TopicGiven a string s, split it into several substrings so that each substring is a palindrome, and find the minimum number of cuts.
IdeasClassic dynamic programming: dp[i] represents the minimum cuts for the first i characters, with O(n²) time.
Follow-upIf we need not only the number of cuts but also all possible partition plans, I answered that we can use backtracking plus DP preprocessing to compute all palindromic substrings in advance.
Overall, the first round went smoothly, and both my project discussion and algorithm solution were recognized.
Round 2: BQ + LRU Cache Design
BQ
Scenario: the product launch date has already been set, and the manager says it must be delivered on time no matter what. I answered that I would plan backward, break down tasks, cut non-core features, and sync risks in daily stand-ups.
Follow-upOne day before delivery, you suddenly discover a serious performance flaw and only have 24 hours left. How would you make decisions and act?
I emphasized rapid risk assessment, urgent communication, prioritizing core functionality, and preparing a fallback plan.
CodingDesign an LRU Cache. You need to implement LRU manually so that both get and put are O(1).
Implementation points:
- Custom Node class (key, val, prev, next)
- Use a doubly linked list with dummy head and tail nodes to simplify boundary handling
- Use a HashMap to store the mapping from key to Node
Follow-upIf it is changed to LFU (Least Frequently Used), how can get and put still be O(1)? I briefly explained that we need to maintain frequency counters and a mapping from frequency to linked lists.
Additional tips
- 英语没听清时，可以礼貌地说：“Sorry, could you please repeat the last part?” 或 “Do you mean I need to implement xxx?”
- When writing LRU-style problems, pay close attention to the order of removeNode and addToHead to avoid losing pointers.
- Keep a good mindset. Amazon interviewers are generally friendly and care more about your thinking process and communication skills.
Recommended resources for Amazon 2026 Intern VO preparation
Finally, here are several resources that I found useful while preparing for Amazon VO:
- Coding practice: LeetCode Amazon high-frequency question list
Focus on arrays, graphs, trees, binary search, and basic OOD problems. Amazon interviews are not only about hard questions; they also value your communication logic, complexity analysis, and optimization thinking while coding. - Leadership Principles：Amazon official Leadership Principles
I suggest going through all 16 Leadership Principles and preparing your STAR stories in advance. The point is not to memorize answers, but to make sure every story can withstand deep follow-up questions. - Interview-experience sites: Glassdoor + Reddit
I mainly checked Glassdoor, Reddit (r/csMajors / r/leetcode), and recent interview experiences on Chinese forums to understand high-frequency questions and interview-style changes. - Mock Interview
If you usually solve problems well but get nervous in real interviews, I recommend doing mock interviews in advance. Simulating the real interview rhythm and practicing expression is more helpful than only grinding problems. - Programhelp Support services
If you are handling multiple processes at the same time like I was and your preparation time is fragmented, you can also look into Programhelp. They provide OA support, VO mocks, interview assistance, and related services. I mainly used it for mock interviews and organizing my interview rhythm, which helped improve my real-time performance.
