Whiteboard Advice

Whiteboard-style interviews are ubiquitous in the tech industry. For those who not had the pleasure, whiteboard interviewing is the practice of asking candidates to solve technical questions on a whiteboard, piece of paper, or computer during the interview. This kind of environment can feel like a pressure cooker and cause even the most competent engineer to fall apart.

The Advice: Communicate!

The best piece of technical interview advice I have received and can impart upon you is to communicate, communicate, communicate! This may seem like an anti-climactic piece of advice, but I hope to be able to demonstrate to you that it’s actually the most important skill to prepare prior to an interview.

What Do You Mean Communicate?

Let’s say you are in the interview and your interviewers throw you a whiteboard question. Do you step up to the whiteboard and feverishly start solving the problem?

No!

That tends to be everyone’s instinct, but it’s definitely not the right way to go. Even if you think you understand the problem, you should take some very important steps before moving forward.

First, Restate the Question

Do you understand what they’re asking you to do? Prove it. Restate the question for them and seek affirmation. You might actually be surprised to find you don’t fully understand what they’re asking for — perhaps the question is similar, but not the same, as a practice problem you have completed in the past.

The interview should give you affirmation or, perhaps, your understanding is incorrect and they will help you understand. There is no situation in which restating the problem will hurt you — it shows you can articulate a problem and gives you time to think it through a bit while you discuss. Furthermore, starting the discussion this way will help quell some nerves that might otherwise manifest while trying to solve the actual challenge.

Ask About Edge Cases

It’s still not time to dive right into coding the solution. Think for a bit about the inputs and expected output and think about potential edge cases to the problem. Ask about them. In many cases, the interviewer hasn’t even thought about edge cases and will make something up. That’s great — it shows you’re analytical and will work hard to try to prevent bugs.

Ask About Test Cases

This is free and you should take advantage of it. Simply ask if there are any test cases that the function should pass. Your interviewer might be expecting you to ask this question, so it might be necessary. But it’s also possible the interviewer was not expecting the question and will think “ah, this candidate knows about testing!”

Write Pseudocode and Ask If It Makes Sense

Again, you don’t actually want to start writing code in an actual language. You’ll find yourself constrained by trying to remember the methods or other idiosyncrasies of the language rather than trying to come up with the correct logic. Instead, let your interviewer know you’re going to start by writing pseudocode and fill in the actual code later.

Here’s the kicker: you can ask if your pseudocode makes sense to the interviewer. It’s possible they will be the type that doesn’t want to “give you hints,” but it’s also possible they’ll be more interested in how you think and want to discuss your pseudocode with you. When I interview candidates, I’m more interested in the latter — rarely do we ever actually develop software in a vacuum.

In other words, in the worst case the interviewer will tell you to continue without actually offering feedback. In the best case, the interviewer might actually point out logical flaws in your pseudocode that will give you some serious benefit when transitioning to actual code.

Write the Actual Code and Ask if it Looks Good

You should now convert your pseudocode into actual code. You don’t even need to remove the comments. At this point, you just need to plug the appropriate code for your language in. If you forget some syntax or a method name, you should be able to ask your interviewer for this information without too much grief. If they give you trouble, just say you’ll leave it as pseudocode for now.

Stuck? Ask for Help!

If you’re having trouble along the way, it’s not illegal to ask for some help. Just phrase it conversationally. For example:

“I’m a bit stuck here, do you have any tips to nudge me in the right direction?”

The answer might be “no, I’d like to see if you can solve it from here on your own,” but it also very well might be a “yes” with a useful tip!