Understanding the Differences Between L3 and L4 Interviews
I'll start by saying this is a personal opinion based on my experience conducting over 400 interviews at Bloomberg, Formation, and my own personal interviews.
One question I often get is about the difference between L3 and L4 interviews. At a high level, the types of questions you can expect are similar, but the expectations differ significantly.
Entry-Level Expectations (L3)
Think of it this way: If I told you someone is entry-level, what are your expectations of them? Generally speaking and keeping it high level for simplicity:
🧑💻 Good Code Competency: The ability to write clean and functional code. An entry-level engineer should demonstrate a solid understanding of basic coding principles and be comfortable with common programming languages. They should be able to produce code that is not only correct but also readable and maintainable.
🛠️ Able to Take a Well-Defined Problem from A to B: Can follow clear instructions to solve a problem. This means that given a specific task with detailed requirements, they can execute it effectively. Entry-level engineers are expected to handle tasks that have a clear path to completion without needing to deal with much ambiguity.
❓ Knows How and When to Ask for Help: Understands their limits and seeks guidance when needed. This is crucial because recognizing when you're out of your depth and asking for help shows maturity and a willingness to learn. It also ensures that issues are addressed before they become bigger problems.
Mid-Level Expectations (L4)
Now, what about a mid-level engineer? Generally speaking, again for simplicity:
💻 Great Code Competency: Demonstrates a high level of coding proficiency. Mid-level engineers are expected to not only write clean and efficient code but also optimize it for performance. They should be adept at using advanced data structures and algorithms to solve more complex problems.
🔍 Able to Take a Partially or Undefined Problem from A to B: Can navigate through ambiguous problems and find solutions. Unlike entry-level roles, mid-level positions often require dealing with incomplete information and figuring out the missing pieces. This involves critical thinking and problem-solving skills to define and execute a plan to solve these issues.
🕵♂️ Can Identify How and Where to Look When Stuck: Knows the resources and methods to overcome obstacles independently. This means they are resourceful and proactive in seeking solutions, whether through documentation, research, or consulting with peers.
Relating This to Coding Interviews
How does this relate to the coding interview process?
When given a problem, how efficiently can you go from the problem statement to discussing your approach and coding the optimal solution? This is a key indicator of your readiness for the role you're interviewing for.
L3 Candidate
An L3 candidate might rush into the problem, making their own assumptions instead of asking clarifying questions. They may not discuss trade-offs of different approaches. However, if their code is clean, they arrive at a workable solution, and they talk through their approach, they’ll likely do well.
For example, if given a problem to reverse a linked list, an L3 candidate might start coding immediately without asking about edge cases or constraints. They might miss the opportunity to optimize their solution because they didn't consider different approaches. However, if their final code is correct and they can explain their thought process, they can still pass.
L4 Candidate
An L4 candidate, on the other hand, should have a general idea of the expected output when given a problem. They should ask clarifying questions to fully understand the problem, even if they think they can solve it with their eyes closed. It’s crucial to show they are not making assumptions. They should also be able to talk through their approach as they code, answer questions from the interviewer without being caught off guard, and ensure their code is clean, coherent, and optimal.
For instance, given the same problem of reversing a linked list, an L4 candidate would ask about the list's potential size, whether it's singly or doubly linked, and if there are any specific constraints they should be aware of. They would discuss the trade-offs between iterative and recursive solutions, and they would write code that handles edge cases effectively. Additionally, they would be prepared to discuss time and space complexity.
The Essential Difference
Essentially, a good L4 candidate would be an exceptional L3; anything less could result in a down-leveling at any of the large companies, or in this market, possibly a rejection.
Mid-level engineers are expected to show a deeper understanding and a higher level of skill. They are seen as potential leaders and mentors for entry-level engineers. This expectation carries through the interview process, where demonstrating an ability to handle complexity, ambiguity, and provide optimal solutions is crucial.
The Importance of Communication
Another key difference in expectations is communication. An L4 candidate must be able to articulate their thought process clearly. This involves not only talking through their approach as they code but also explaining why they chose one method over another, what trade-offs were considered, and how they ensured the solution is optimal.
Communication skills are vital in a collaborative environment. Mid-level engineers often work with cross-functional teams and need to convey technical concepts to non-technical stakeholders. This ability to bridge the gap between technical and non-technical team members is a valued skill in higher-level roles.
Preparing for the Interview
If you're preparing for an L4 interview, focus on honing your problem-solving skills, improving your coding proficiency, and practicing clear and effective communication. Here are a few tips to help you prepare:
Consistent Practice: Regularly solve coding problems on platforms like LeetCode, HackerRank, or CodeSignal. Focus on a variety of problems, especially those that are more complex and require deeper thought.
Mock Interviews: Participate in mock interviews with peers or use platforms like Pramp or Interviewing.io. This will help you get used to the interview format and receive feedback on your performance.
Study Data Structures and Algorithms: Ensure you have a strong understanding of data structures and algorithms, as these are frequently tested in interviews. Study their implementations, use cases, and complexities.
Understand System Design: For higher-level roles (L5), you may be asked system design questions. Familiarize yourself with designing scalable systems, understanding trade-offs, and justifying your design choices.
Practice Communication: Work on explaining your thought process clearly and concisely. Practice discussing trade-offs and answering questions on the fly.
Conclusion
I hope this was helpful! 🚀 If not, let me know so the next post can be better 🤣. My goal is to provide insight and advice where I can.
Feel free to leave your thoughts and questions in the comments below, and to subscribe to my blog for more tips and insights!
Thank you for sharing, it is informative