What does the perfect FAANG coding interview look like?
Let's talk about how to send "hireable signals" to your interviewers — and how to prep for your interview efficiently.
One of the most frequent questions I get from learners is: what does the perfect coding interview loop look like?
I have interviewed hundreds of software engineering candidates throughout my career. I have also been through quite a few loops myself as a candidate (and have even failed some when I wasn’t prepared). Here is how I recommend approaching your coding interviews to make yourself as hireable as possible.
It’s more challenging than ever to stand out as a candidate. Only about 20% of candidates that make it to the full loop phase are expected to advance. If you have only made it to the screen, your odds are more like 10%. Pre-screen, your odds of getting hired at a top company (e.g. FAANG) are less than 1%.
Of course the coding interview is just the tip of the iceberg in a full FAANG loop. At most top companies you will have to complete multiple coding interviews, as well as at least one System Design Interview (more for senior roles) and a behavioral interview.
That means a strong coding interview isn’t just important for getting hired — it’s table stakes.
Of course, at the top tech companies in the world, there is no shortage of qualified applicants. With so much competition, you simply will not get the benefit of the doubt. You need to go above and beyond to convince your interviewers that you are hireable — and you need to do so quickly.
So how do you quickly convince interviewers that you are hireable? By sending them the right signals.
How do I prove I’m the best candidate… in only 45 minutes?
When I would sit on hiring loops at Facebook and Microsoft, my fellow interviewers and I were looking for certain “hireable signals” from the candidate. These signals are very concrete. They may vary from company to company, but in the coding interview, they look pretty much like this:
Coding competency
Problem solving ability
Ability to ask clarifying questions
Ability to explain one’s thought process
Coding interviews at the world’s top tech companies are always team-based. Each person on the loop is typically screening for different areas, i.e. looking for different signals. If the hiring committee doesn’t get enough signals from you, then you’re a no-hire.
In this sense, your job as a candidate is straightforward: how do I send enough “hireable signals” to my interviewers during the loop?
In my experience, it comes down to two key things:
Efficient use of time during the interview
Effective preparation before the interview
Let’s start with #1:
Efficient use of time during the interview
If you have ever been in a coding interview, you know that it’s over in a blink of an eye. You typically get only 45 minutes per interview. In reality, those 45 minutes include only 30 minutes of actual coding and problem-solving, after you factor in greetings, getting situated, explanation of the problem, and questions at the end. (30 minutes is really the best case scenario — I actually used to tell candidates to budget for about 20-25 minutes of actual coding).
That means you need to give enough hireable signals in that 30 minute window. This is where most candidates run into trouble.
It happens all the time where a candidate understands the question and knows how to write the code… but they just need more time to do it. (I was actually told this by a screener at Facebook; they were impressed by my previous work experience and skills, but knew I was rusty in a coding interview environment and would be too slow to pass the interview. Luckily for me, they actually recommended that I delay my coding interview loop to take more time to prepare — which is a story I definitely plan to tell in a future newsletter).
In order to be fluent in an interview, you need to achieve a level of proficiency solving “toy problems.” These toy problems are not typically relevant to your day-to-day work, but in order to get hired, you need to prepare for them nonetheless.
That brings us to #2:
Effective preparation before the interview
Effective preparation is all about learning how to optimize your limited coding interview window. In short, you need to feel comfortable doing these two things before you even write your first line of code:
Quickly identify a few possible solutions based on the type of problem you are encountering
Quickly eliminate all other solutions that don’t fit
I call this “reducing your solution space.” This is actually a skill you can learn with the right preparation (I’ll explain how in a bit). But first, let’s get back to the perfect loop.
When people ask me about the perfect FAANG coding interview loop, here is what I tell them.
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The perfect FAANG coding interview loop (in 5 steps)
If you do these 5 things competently in your coding interview, then I typically have enough signals to recommend you:
1) You ask the right clarifying questions at the start of the loop
The goal here is simple: Understand the intent behind the interview question.
Asking thoughtful questions is a good way to show the interviewer that you are thinking critically about the problem. On a practical level, this is your opportunity to identify the pattern behind the question you are being asked, which will enable you to identify the correct solution more quickly. You need to be able to recognize the underlying pattern just from looking at the problem statement (I will share how to do this at the end).
One final note: sometimes interviewers will deliberately leave out a few key details when explaining the problem. They do this because they actually want you to ask clarifying questions. If you fail to ask those clarifying questions at the top of the interview, you may run into issues later on.
I cannot understate the importance of this step. You will save yourself valuable time later on by asking the right questions from the start.
2) You propose a few possible solutions
As we know, every minute counts in a coding interview. You can set yourself up for success with strategic preparation.
I highly recommend using a pattern-based approach to interview prep. Once you understand the problem, it enables you to efficiently triage possible solutions. If you understand the pattern behind a problem, you can quickly zero in on a small set of possible solutions, which dramatically reduces the number of solutions you will need to test.
For example, say you are asked a question about nuts and bolts. You might recognize that this is what we call a quicksort problem, and you need to identify partitions.
At this step, it also helps to walk the interviewer through your thought process.
3) You try a solution (and write the code)
Once you fully understand the problem and know how to structure your solution, writing the code is the easy part (as long as you are comfortable coding in the language of your choice).
Most solutions in a coding interview should be no more than 5-10 lines.
4) You test your code
A lot of people miss this step. Do not miss this step. Run through examples to validate your solution.
Taking the time to test your code is important for many reasons. It shows that:
You can code competently
You have established the habit of testing your code
If you encounter a bug, you can fix it
You can evaluate the merits of different solutions
One last note: a lot of people miss on validating basic inputs. This is a telltale sign that they aren’t careful coders, which is disqualifying in most cases.
(An example: I want you to write a function that converts LBs to KGs. In order to solve this properly, you need to remember to bypass a negative integer. That’s just common sense: you can’t have a negative weight. This is also a reminder to be sure to ask good questions to identify all of your constraints before you get started).
5) You are able to talk through your thought process
Your interviewer will have follow-up questions. Be prepared to speak to the choices and trade-offs you made. This is where you can demonstrate your deeper understanding of the problem. This is also where people who don’t fully understand the problem get caught.
We see candidates “copy and paste” solutions from memory all the time. Sometimes they even try to pretend like they didn’t already know the specific solution beforehand, and try to play it off like they are solving the problem in real time. However, a calibrated interviewer will catch this every time.
But here’s the most important thing: this “copy and paste” approach does not work at scale. You simply can’t expect to practice every toy problem you might encounter. LeetCode now has over 2,400 problems. It’s simply not feasible to practice and/or memorize them all. It’s impossible to send enough hireable signals in 45 minutes (again, more like 30 minutes) without a more structured approach.
So now that we know what the perfect interview loop looks like, let’s talk about how to prepare yourself for the big moment. We already know that success in coding interviews requires both efficient use of time during your interview and effective preparation ahead of time.
How do you prepare for the coding interview the right way?
How to prepare efficiently for the coding interview
In order to achieve the perfect interview loop, here’s how I tell candidates to prepare:
1) Brush up on the fundamentals of your programming language (and coding interview basics)
Choose the programming language that you feel most comfortable working in. Most companies won’t care which language you use, as long as you show mainstream proficiency. (I personally always used C++ in my coding interviews, because that’s what I’m comfortable with. Even though Python is a more efficient and less verbose language, I feel far more confident and fluent in C++. So that’s what I use).
You’ll likely be nervous during your interview, so it’s easy to blank on even the basics. This part needs to be automatic. Don’t waste time trying to recall in real-time. Every second counts.
After brushing up on your language, I would dig into data structures and algorithms. Remember to review topics like:
Complexity Analysis (a.k.a BigO)
Arrays
Stacks
Queues
Linked List
Trees
Tries
Graphs (BFS and DFS)
Hash Tables
Heaps
Sorting
Searching
I also recommend looking at relevant APIs (e.g. string processing, math functions, etc.), which will help you move faster in the coding portion of the interview.
2) Practice pattern matching
Now it’s about putting your skills into practice — and to get comfortable moving fast.
To do this, you could attempt to run through thousands of practice problems on websites like LeetCode. However, this is not an efficient way to do things (and it’s definitely not how the most successful developers in the industry prepare).
This is why I recommend a pattern-based approach to coding interview preparation.
If you are just drilling practice problems, you are missing something very important. You aren’t developing a framework for pattern matching in your head that enables you to connect problems to other problems you have seen before. In short, you aren’t internalizing the “why” behind each question.
Without seeing the underlying pattern behind common questions, it becomes extremely difficult to efficiently solve new problems in real-time.
This pattern-matching approach becomes especially useful when exploring and validating potential solutions. Recognizing the pattern behind each question enables you to quickly eliminate solutions that don’t fit, and reduce your solution space to only a few applicable solutions. Then you can test the remaining solutions, and arrive at your final answer much quicker.
This is exactly why we created our new Grokking Coding Interview Patterns course. It was designed to help you make that pattern recognition automatic.
Think of yourself like an Olympic table tennis player that decides in milliseconds what kind of shot they will use. The point is for this pattern recognition to become second nature, and that you build the muscle memory you need to be successful in a lightning fast coding interview loop.
So I invite you to give Grokking Coding Interview Patterns a try. We created this course specifically to help you send hireable signals to your interviewers. It will teach you problem solving, pattern recognition, and will enable you to prepare more efficiently than you would just drilling endless practice sets.
I hope the “perfect” coding interview loop feels more attainable now. With some strategic preparation, I am confident that your ability to send hirable signals will become second-nature.
Happy learning!