Acoding interview is the most standard process to measure the capability of an engineer candidate. As the COVID-19 pandemic continues to spread, most of the tech companies switched to “virtual onsite” interview now. Although each interviewer has his/her own style and each question is different, they all collects the same group of signals to judge the candidate is qualified or not.

In this article, I am going to unveil the types of signals interviewers are looking for and some important tips to help you get prepared for an online coding interview.

Image from educative.io

Over-Prepare

Among all types of interviews(coding, behavior, system design), the coding interview is actually the easiest one to prepare and score. Because in most cases, there’s only one version of the optimal solution.

To prepare it, when scheduling the interview with a recruiter, ensure you have enough time to charge your confidence by doing massive coding questions practices. You can easily find some coding interview practices website online. I am not going to make any recommendation here.

To help you get the most result from your practicing time, there’re some tips.

Stick to One Language

The language itself doesn’t matter that much, from my experience, so it’s best to choose whatever language you are most familiar and comfortable with for practicing and interview. No matter what you choose, C++ or Python. Ensure you understand some basics of this language, like:

1. How is this language being executed by a computer? Compile or Interpret?
2. Parameters are passing by value(copy), pointer, or reference?
3. How this language manage memory?

Practice Selectively

Nowadays, the number of coding questions is way more than someone can consume within a month. When practicing, be selective is critical. Typically, you need to get yourself familiar with the representative questions in following categories:

1. String manipulation
2. Tree traversal
3. Interval scheduling
4. BFS, DFS search problems
5. Two-dimension “Dynamic Programming”

Noted that there are some hard problems online, like “Red-Black Tree”. From my experience, it’s rarely being asked, if your time is limited, I will suggest prioritizing other more representative ones.

Image from iglu

Signals Interviewer Collects

For the interviewer, we are constantly trying to extracting signals from communication and written code.

Understand the Input and Output

After presenting the question, usually, the interviewer will expect the candidate to ask some questions regarding the function signature, specifically the input and output type.

This is a great differentiator that distinguishes whether a candidate has experience in writing code in the real-world setting or not. Typically, a candidate should check:

1. Parameters are null or non-null
2. Parameters are empty or non-empty
3. Should throw an exception or return if the input is illegal

Always ask for some examples for the coding question, these can help test code as well.

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