Technical Interviewing Formats
Technical interviews are where the magic happens. It’s where you get to meet potential teammates and collaborate with other professionals in your field to solve problems.
Interviewers may approach the tech portion differently, but the objective is always the same: assess whether you are the right person to join their team.
No need to worry though. You’ve been building your technical skill set for months and now it’s time to show off those skills! Let’s go over the different formats and how best to prepare.
Formats
There are a number of different formats for technical interviewing. You may encounter one, some, or all of these formats during your interviewing journey. Every company interviews in a different way. Some may start with a code or data challenge, while others start with whiteboarding and save the code challenge for the end. Be ready for anything!
Here is a list of the types of interviews you can expect and should be prepared for.
Coding challenges
Week long coding (or data) project
Timed technical assessment
HackerRank or Codility challenge
Data science case study
Technical phone screens
Trivia
Pair-programming
In-person technical interviews
Trivia
Whiteboarding
Pair-programming
Coding Challenges
Code challenges are when employers ask you to build a feature or application within an allotted time, sometimes in a specific language, sometimes in a language of your choice.
Data challenges/data code challenges can range in depth and breadth. They test your skills in data manipulation, cleaning, and predictive modeling. Sometimes, the challenge may be in the form of a case study, in which you may be given a business question and a dataset and asked to figure out how the data can be used to answer the business question.
Think of it half as an extended technical interview and half as you working on a project with the company. As noted, typically these challenges come with a set of instructions, some acceptance criteria, and a specified due date.
As we’ve talked about in other pieces of content, this activity may be the first step, a middle step, or the final step in a company’s interview process.
Technical Phone Screens
Typically there are two types of technical phone screens:
Trivia: essentially a Q&A session. The interviewer will quiz you on terminology:
What’s the difference between == and === in JavaScript?
What does MVC stand for and how does it work?
Describe the fundamental differences between Random Forest and Gradient Boosting algorithms (data science)
Questions in math and statistics, and/or programming and databases (data science)
To do well, you’ll need to study. An easy way to find interview questions is simply to google Interview Questions <Language> with being whichever language the job requires (e.g. Ruby, JavaScript, etc. (software engineering), or Python or SQL (data science). You can, and should, also read technical books like:
Note: this style of interview is a relic from the past and is becoming less common than pair-programming, but still exists (and you should still be prepared for it!):
Pair-programming: sites like CoderPad have recently enabled remote programmers to share code in real-time. This has shifted technical interviewing from the Q&A format to a more collaborative exercise.
Typically, the interviewer will ask you to solve an algorithmic problem and ask you to code a solution (just like how you solve labs). You’ll be able to view each other’s code on-screen and make edits in real-time. If you get stuck, they’ll likely give you hints. If you finish quickly, s/he might ask you to optimize your answer and do even better. What s/he’s doing here is implicitly asking you about Big-O and how efficient your solution is. Make sure to read up on Big-O notation.
The point of pair-programming is to gauge how you solve problems, how you communicate, and how easy it is to work with you.
You should feel comfortable Googling anything you need to. The interviewer will stop you if it’s not okay. Always try.
Both formats are typical for first-round interviews and usually last 30-60 minutes.
In-Person Technical Interviews
In-person interviews tend to come later in the process once you’ve passed a phone screen and/or completed a technical phone interview or code challenge. In-person technical interviews are often a mix of trivia and whiteboarding or pair programming.
Trivia we’ve already covered. Instead of being asked over the phone or Hangout, you’ll be asked questions in person.
Whiteboarding:
This is the most traditional type of technical interview and is where you are asked to solve an algorithm question using a marker and a whiteboard. You might be asked a question like:
Given an array_of_ints, find the highest_product you can get from three of the integers.
Then you stand at a whiteboard discussing the right solution with your interviewer while writing out the code by hand. Interviewers want to see that you can code the solution without a computer and communicate effectively.
If you can’t remember the method to return the first item in an array and remove it, just ask. It’s not a memorization problem.
Feel free to have magic methods that remove some of the incidental complexities. For example, if I was designing an algorithm to find if a number was prime, and I needed a method to find if a number was divisible by 1 through 10, I would just say “ok I have a magic is divisible method.” Sometimes they will say no-go and have you implement it; other times they’ll be fine with it.
Pro-tip: Be vocal! Walk your interviewer through your thought process and ask questions throughout the process to ensure you fully understand what’s being asked of you. A big piece of critical feedback employers often have is that candidates don’t talk enough in technical interviews
Pair-programming.
Pair-programming we also covered earlier, but this time it’s in person. An added bonus here is that you’ll develop a strong understanding of what it might be like to work with that person.
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