How to Solve the Most Asked Whiteboard Interview Questions at Google — 2021

A whiteboard interview is an opportunity to showcase your technical skills, thinking capability, and communication skills. Technical interview preparation for any software engineering or related management role at Google involves whiteboard interviews. There are, however, some unique challenges associated with whiteboard interviews. This article addresses the associated challenges and provides tips to help you prepare for your Google whiteboard interview.  

If you are preparing for a tech interview, check out our technical interview checklist, interview questions page, and salary negotiation e-book to get interview-ready! Also, read How to Get Software Engineering Jobs at Google and How to Prepare for Google's Onsite Interview for specific insights and guidance on Amazon tech interviews.

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In this article, we’ll cover:

  • Whiteboard Interviews at Google 
  • Key Topics to Prepare for Google Whiteboard Interview
  • Whiteboard Interview Prep: Before the Google Whiteboard Interview
  • Whiteboard Interview Prep: During the Google Whiteboard Interview
  • The UMPIRE Method
  • Whiteboard Practice Questions: Google Algorithm Interview Questions
  • FAQs on Whiteboard Interviews

Whiteboard Interviews at Google

Whiteboard interviews are a test of your problem-solving capabilities in real-time. They are also a way for the interviewer to understand your thought process. You need to write your code without a code editor that would usually help you with syntax. If the syntax comes naturally to you, it’ll help you focus your attention on problem-solving. Knowing the syntax of the language you’re using well will help boost your confidence. 

As you solve the problem, the interviewers will watch what you do and listen to what you think. Think out loud when making tradeoffs and other important decisions. They’ll also ask questions throughout the process of you solving the problem. The problem-solving can take up to 60 minutes, and the entire interview may take a full workday.

It’s okay to make some mistakes during the interview; in fact, you’re quite likely to. The test is how you handle them.

Key Topics to Prepare for Google Whiteboard Interview

Not all topics carry equal importance in coding interviews, although strong fundamentals are essential to clear any Google interview. Some of the topics you should make sure you’re exceptionally skilled at include:

  • Sorting
  • Graphs
  • Big-O Notation
  • Recursion
  • OOP
  • Data structures and algorithms
  • APIs
  • Mathematics
  • Testing code

Whiteboard Interview Prep: Before the Google Whiteboard Interview

Given the unique challenges associated with whiteboard interviews, preparing for them well before the interview is crucial. Here are some steps you can take before your whiteboard interview to put your best foot forward:

  • Practice solving questions on a whiteboard or paper without the help of an editor. 
  • Choose one or two OOP languages you are comfortable with and become excellent at them. It’ll help you to know their syntax well.

Recommended Reading: Most Popular Coding Languages for FAANG Interviews in 2021

  • Practice previous interview questions by pausing at every moment of decision making and explaining your thought process to a friend for practice by thinking aloud.
  • Think about the possible questions interviewers can ask you at each step. Doing this exercise will help you understand the kinds of questions you can expect at your whiteboard interview.
  • Do a few mock interviews. IK offers mock interviews with FAANG hiring managers to help you with your preparation. Click here to learn more. 
  • Watch a mock interview to learn more about the ideal tonality, pace, non-verbal cues, posture, etc.

Keep in mind that along with rigorous prep, you also need adequate rest and a calm state of mind to nail that interview:

  • Adjust your sleep schedule to make sure you are at your best during your whiteboard interview, whatever the timing may be. Being fresh is crucial because you need to think on your feet, implement the solution and effectively communicate your problem-solving process all at once.
  • Make sure you have everything you need for the interview the night before.
  • Wind down early the night before the interview and engage in calming activities like mindfulness or whatever works to calm your nerves if needed.
  • Dress appropriately and comfortably for the interview.

Whiteboard Interview Prep: During the Google Whiteboard Interview

You’ve got your preparation right, and you’re fresh and ready for the interview. It’s D-day. There are specific steps during the interview you’d be wise not to miss. Here are some of them:

  • Do choose the OOP language you’re most comfortable with for the interview. You can often change the language if it is better to solve a particular question using it. That said, you need to explain your reasoning for the change.
  • It would be best to ask follow-up questions until you are clear about precisely what the problem is and what the constraints are.
  • You should verify and state any assumptions you make.
  • We highly recommend you pause before solving a problem instead of quickly starting to code with whatever solution comes to you first. Plan your approach well and then move forward.
  • Explain the decisions you take and tradeoffs you make and why. When you’re working through something, talking aloud will help them see how you handle it when you get stuck and how you get yourself out of it. They evaluate you based on this, so be sure to showcase how you think about solving problems.
  • A fully implemented but not-so-optimized solution is better than having no implemented code at all, despite coming up with the most optimized solution. Aim to have at least one working solution at the end of the interview, even if you can’t implement or develop the most efficient solution. It is essential to manage your time correctly to make sure you have that choice.
  • Review your solution in terms of time and space complexity, and think aloud, so your thought process is evident to the interviewers. Be clear and confident; try to speak at a moderate pace. Take a pause and take time to think when needed.

The UMPIRE Method

Much of what we discussed in detail above is effectively abbreviated and included in the UMPIRE problem-solving framework. According to UMPIRE, the problem-solving process goes in the following order:

  • U: Understand the problem
  • M: Match the problem with the interviewer
  • P: Plan your approach and solution
  • I: Implement your solution
  • R: Review your solution
  • E: Evaluate your solution

Remembering this acronym can help you quickly check to ensure you don’t forget any critical steps as you focus on problem-solving, communicating, and answering the interviewer’s questions.

Whiteboard Practice Questions: Google Algorithm Interview Questions

Now that we have an idea of what to expect and how to prepare for the whiteboard interview, let us look at some of the coding questions that have been asked to software developers, coding engineers, and others at Google whiteboard interviews:

  • Given: An array of integers, a target number. Task: To return the indices of the two numbers in the array that add up to a specific target number. Allowed assumptions: Each input has only one solution, and the same element cannot be used twice.
  • Given: The union of ordered sublists. Task: Create an ordered list from it.
  • Task: Generate all unique possible letter racks in scrabble.
  • Given: An array with non-negative integer characters. Task: Find the contiguous subarray that comprises the maximum sum.
  • Given: An array of size N-1, with numbers ranging from 1 to N- but one number missing. Task: Find the missing number.
  • Given: An array of size N, comprising sets of zeroes, ones, and twos. Task: Sort the array in ascending order.
  • Given: Two sorted linked lists. Task: Merge the two linked lists.
  • Given: A linked list. Task: Find the middle element of the linked list.
  • Given: A String. Task: Find the longest substring with only distinct characters.
  • Given: A linked list. Task: Implement loop detection and loop removal functions for the linked list.

Check out our Problems page for more coding questions with solutions.

FAQs on Whiteboard Interviews

Q. Where do I start my preparation for my Google Interview?

You can start by visiting Google’s careers page and going through the requirements for some of the job opportunities of your interest. Also, learn about their goals, values and check out Google’s official tech dev guide. We also recommend checking out our article on Google Coding Interview Questions.

Q. How can IK help me prepare for my Google Whiteboard Interview?

Whether you’re applying for the role of a software engineer, engineering manager, or tech lead, we at Interview Kickstart have got you covered. 

IK is the gold standard in tech interview prep. Our programs include a comprehensive curriculum, unmatched teaching methods, FAANG+ instructors, and career coaching to help you nail your next tech interview.

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