最近我们这边有几位同学陆续完成了 eBay (web auction company) Software Engineer / Data 相关岗位的 Online Assessment（OA）。作为长期陪跑 eBayOA 的辅导导师，我们也第一时间帮学员做了完整复盘，把 流程、题型分布、易踩坑点 系统性地整理出来，供正在准备 eBay 或同类大厂 OA 的同学参考。
In summary, eBay’s OA style is quite typical:
It does not pursue "fancy algorithms", but has high requirements for basic skills, code robustness, and business understanding. It falls into the category of "it doesn't look difficult, but it is actually very easy to overturn".
EBay OA overall process overview
Judging from the feedback from students, most eBay technical position OAs have the following characteristics:
- Platform：HackerRank/CodeSignal (slightly different for different positions)
- Question volume:
- Often asked are 2 programming questions
- Some positions will be overlaid with SQL/Data processing questions
- Duration: 60 – 90 minutes
- Language: Python/Java/C++/JavaScript optional
- Do you value complexity analysis?: Yes (but more emphasis is placed on whether it is “reasonable and stable”)
To summarize in one sentence:
The core of eBay OA is not "whether you know the optimal solution", but "do you look like a person who can join the team and write production code?"
EBay OA real test examples (real investigation direction)
Shared below are real examples of question types that have appeared in eBay OA that we compiled during the coaching process. The question itself does not pursue extreme algorithmic difficulty, but places great emphasis on rule understanding, code stability, and ability to handle details. This is also the core criterion for eBay's technical selection of candidates.
Real question 1: Array piecewise subtraction simulation (Simulation + Greedy)
Core description of the topic:
You are given numbers, an array of non-negative integers.
Repeatedly find the leftmost non-zero elementX,subtractXFrom consecutive elements to the right until subtraction is no longer possible, and addXTo the final result.
Return the total accumulated sum.
Focus of inspection:
- Patience and accuracy in simulation problems
- Strict understanding of "leftmost non-zero" "stop condition"
- Whether it can correctly handle multiple rounds of iteration and array state changes
Instructor comments:
This question is not difficult, but it is quite easy to make mistakes due to incomplete understanding of the conditions. We saw in the review that students who overturned were often not algorithmic problems, but:
- One less break condition is evaluated
- Or the processing on loop boundaries is not rigorous.
EBay likes to use this kind of question to see whether a candidate is suitable for writing production-level logic code.
Real question 2: Statistics of upper and lower case letters (String Traversal)
Core description of the topic:
Given a string consisting of uppercase and lowercase English letters,
Return the difference between the number of uppercase and lowercase letters.
Focus of inspection:
- Basic string traversal
- Familiarity with character ranges/ASCII/built-in functions
- Whether it is possible to write a clear, readable, and unambiguous implementation
Instructor comments:
This is a typical question that "looks like a question for scoring points, but is actually used to screen out details."
In the OA scenario, eBay pays more attention to:
- Can you write it right at a glance?
- Is there any redundant logic?
- Are there any hidden bugs (such as misjudgment of non-alphabetic characters)?
Real question three: Binary state + operation sequence simulation (State Machine)
Core description of the topic:
You are given a binary array
StateAnd a list of operations:
"L": set the smallest index with value 0 to 1"C(index)": setState[index] = 0
Return the final state as a binary string.
Focus of inspection:
- Accuracy of status updates
- Ability to parse operating instructions
- Whether it can handle "no change operation" stably
Instructor comments:
This type of question appears frequently in eBay OA. The essence is:
- Business rules → program state mapping capabilities
- Rather than algorithmic brilliance
Interestingly, even in the official examples, individual steps themselves appear to be "ambiguous" and it is exactly what eBay wanted to test:
Can you write code strictly according to the meaning of the question instead of according to your feelings?
The real screening logic of eBay OA can be seen from the real questions
It can be clearly seen from these questions that eBay’s OA is not being tested:
- Advanced DP
- Unpopular data structures
- Math skills
Instead, we are repeatedly verifying three things:
- Do you understand the requirements accurately?
- Is the code you write stable and maintainable?
- Do you have engineering thinking, not just problem-solving thinking?
This is why when we coach eBay OA, we focus on:
- Breakdown of real question types
- Multi-round state simulation training
- Error-prone points are exposed in advance
Instead of just piling up problems.
EBay OA Frequently Asked Questions FAQ (instructor Q&A version)
Based on the recent real OA feedback from many students, we have compiled some frequently asked questions to help you avoid common misunderstandings.
Q1: Is eBay OA difficult? How far does it need to be brushed?
Answer:
Not difficult, butVery "card details".
The difficulty of eBay OA is not the algorithm ceiling, but rather:
- Is the understanding of the question complete?
- Is the status change rigorous?
- Are the boundary conditions written correctly at one time?
If you only pursue AC when answering questions and do not pay attention to code stability and engineering sense, it will be easy to overturn in eBay OA.
Q2: Is the optimal solution (O(n) / O(log n)) required?
Answer:
It’s not mandatory, but you have to “explain it.”
From actual evaluation:
- For most problems O(n) or O(n log n) is sufficient
- What will really be deducted are obviously violent solutions + no awareness of complexity.
EBay is more concerned about:
Do you know what the code you wrote is doing, rather than "happening to run through the sample".
Q3: I understand the examples, but I make mistakes as soon as I write them. Is this normal?
Answer:
Very normal and yes EBay OA’s “Classic Filtering Point”.
Many students will mention during review:
- Examples can be understood
- But when I was writing it, I missed a certain step of the condition.
- Or if the loop order is slightly different, the result will be incorrect.
This is why we force students to repeat the rules of the questions themselves during tutoring instead of typing the code directly.
Q4: Will OA be down directly because of a small bug?
Answer:
Depends on the nature of the bug.
- Fatal logic error / large number of cases However → High risk
- Small boundary errors/few case failures → There is still a certain probability of entering the next round
But the reality is:
EBay's OA is often the first round of hard screening, and there is not much room for error.
About eBay OA "Incognito writing service"illustrate
The real problem that many students encounter in the eBay OA stage is not "not being able to write at all", but:
- Time is extremely tight
- No room for trial and error
- Once you fail the first round, your resume will be invalid for a period of time.
At this high-risk node, we also provide OA practical support solutions for some students, with only one core goal:
Pass the OA smoothly and enter the manual interview stage.
Our OA support focuses on:
- Quickly break down the questions and clarify the test points
- Stable, operable, logically rigorous implementation solution
- The entire process does not affect your account, equipment, or subsequent interview process.
- Leaves no trace and does not affect background checks and subsequent rounds.
Many successful cases have repeatedly verified one point:
What really sets eBay apart is the technical and system discussions behind it, rather than OA itself.
