How (Not) to Prepare for a Technical Interview

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There are plenty of programs and people out there who can tell you how they think you should prepare for a technical interview. But in my years of interviewing candidates at Facebook and Nextdoor, I’ve seen engineers make the same common mistakes during their interview prep. While there isn’t necessarily a one-size-fits-all approach, there are a few things you should avoid doing if you want to ace your technical. I’ll explain the 4 most common mistakes I’ve seen and why your approach to interview prep should not include them.

What to Avoid When Preparing for a Technical Interview

While this isn't an exhaustive list, these are the top mistakes I've seen engineers make when gearing up for a technical interview.

1. Memorizing solutions

I’ve seen too many software engineers interview prep by memorizing solutions. They try to brute force prepare by seeing every problem and knowing the solution to each one. The very first thing you have to accept is that, in an interview, you will likely not know the questions being asked nor will you have ever heard of them. There are very few technical interview questions you'll come across multiple times. Memorizing solutions isn't going to get you any closer to landing that next role.

There’s a difference between actually learning why a solution works and memorizing one. When you learn why a solution works, it allows you to apply that technique to new problems. When you’re just memorizing the lines of code to a solution, you don’t understand the reason behind why it works, you only know that it works for this specific problem. This won’t help you when you’re in an interview and you get a technical interview question you’ve never seen before. That’s why it’s so important when preparing for an interview to not just memorize solutions, but to understand the "why" behind them.

2. Leetcoding in silence

Leetcoding is a great way to practice solving problems as you prepare for an upcoming interview. Unfortunately, too many great engineers are Leetcoding in silence. What I mean by that is many engineers are solving Leetcode problems exclusively in their head and not talking about their process out loud. By doing this, they’re failing to prepare for one of the most important things that the interviewer is evaluating for—your collaboration and problem-solving abilities.

Here’s what you should do instead:

1. When practicing, record yourself explaining your approach out loud and listen back to it a few days or even weeks later.
2. If your explanation still makes sense to you, great!
3. If your explanation doesn’t make sense or it’s too long, iterate on it until it feels right. Often, it only takes a few sentences to explain a great solution.

3. Studying hard problems

Spending time solving hard problems isn’t necessarily wrong, but it’s not the most efficient way to prepare for a technical. But by far, what I’ve found almost unanimously, is that engineers preparing for interviews are spending too much time solving hard problems instead of perfecting their solutions to easier problems.

Too many engineers are not spending enough time on easy problems. And when I say easy, I mean really easy, like as simple as trying to find the sum of all the elements in a binary tree. Here are a few tips when it comes to solving hard problems to prepare for a technical:

1. A general rule of thumb is that if given an easier problem, you should be able to solve it in 20 seconds flat. If that’s not the case, you should dedicate more time to solving easier problems.
2. More often than not, engineers don’t fail technical interviews because they can’t solve problems, they fail because of execution. If you were interviewing for a writing role and you stumbled over basic grammar questions, your interviewer would question your foundational writing skills. The same goes for technicals. You need to have a solid grasp of the basics to show your interviewer you know what you’re doing.
3. So many engineers over-rotate and prepare for a technical by studying only the hardest problems because the idea of getting a really hard problem in an interview is terrifying. In reality, the vast majority of technical interview questions are actually easy or medium difficulty level. Execute well on an easier problem and it will tell the interviewer all they need to know.

4. Cramming

We’ve all had times in our lives where we’ve crammed for something. Maybe you crammed for a Biology test or perhaps you crammed all your errands into one day. While it may have worked in those instances, cramming is not an ideal way to prepare for technical interviews. Here’s why:

1. Think about preparing for a technical in terms of lifting weights at the gym. You probably wouldn't cram all your lifting for the week into one day, right? Instead, you’d alternate between lifting and a day of rest. The days off recharge you and allow your muscles to rest. The same is true for interview prep. Taking time off between solving problems allows your brain to absorb the information and knowledge you’ve gained and making it more likely that you can apply it.
2. Cramming automatically puts you in a bad mindset. You’re creating a learning journey that’s filled with panic and anxiety. Additionally, you might also be sacrificing components of your wellness that are important if you want to be your best self in an interview.
3. Preparing for a technical interview is like training for a marathon. You wouldn’t run 20 miles the day before the marathon, you would take the day off or run fewer miles. In the same vein, reducing your studying in the days/week leading up to the interview and spreading out your preparation will allow you to focus on having a clear state of mind during the interview.

Technical interview preparation doesn’t have to be frantic or chaotic. In fact, with the right plan in place and plenty of time to study, you’ll go into the interview with confidence.

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