38 Binary Tree Interview Questions (With Sample Answers)

By Indeed Editorial Team

Published April 2, 2022

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

A binary tree lets you store hierarchical data, unlike a list ideal for linear data. As a programmer, it's vital to master binary tree questions when preparing for coding interviews. Knowledge of frequently asked binary tree interview questions may help you impress the hiring manager and secure employment. In this article, we review 38 common binary tree interview questions to help you prepare for your next interview.

General interview questions

A hiring manager usually asks general questions to understand candidates better when starting an interview. The questions to expect here may range from queries on work ethic to your career goals. Here are 14 examples of general questions you're likely to encounter during a binary tree interview:

  • How did you hear about this position?

  • What's something interesting you can tell us about yourself?

  • Why do you want this job?

  • Why did you choose our company to hire you?

  • Do you work best when alone, or do you prefer working with a team?

  • How do you deal with stressful situations or pressure?

  • How do you prioritize your work?

  • What are some of your career goals, and how do you intend to achieve them?

  • What do you think our company could do to be better or different?

  • If you were an animal, which one would you be?

  • What missing information on your resume does the hiring team need to know?

  • Are there any other companies interviewing you?

  • What kind of workplace environment do you prefer?

  • Have you ever disagreed with a superior's decision at work?

Related: 21 Job Interview Tips: How To Make a Great Impression

Experience and background questions

The second part of the interview is where the interviewers ask about work experience and background to verify your competence. Hiring managers also ask these questions to determine your accomplishments, performances on previous projects or the jobs you've held. Based on what you know about the company, try to give answers that directly relate to the vacant position. Here are 11 questions about experience and background to familiarize yourself with and reflect on your potential answers:

  • What is a binary tree?

  • What is a binary heap?

  • What are your first steps when creating a new binary tree?

  • Can you explain some projects you have on your resume?

  • What more can you tell us about your work experience?

  • Which programming language do you prefer ?

  • What is your most outstanding professional achievement?

  • How have you grown your skills in your last role?

  • What do you dislike most about binary trees?

  • Can you define what a binary search tree is?

  • How do you stay updated with advances and current trends in the industry?

Related: Interview Question: "Tell Me About Your Work Experience" (With Example Answers)

In-depth questions

Hiring managers use in-depth interview questions to collect data through conversations while gaining insights into your behavior, attitude and perception. When answering, give detailed explanations to demonstrate your understanding of your role and the industry. Here are some examples of in-depth questions to expect in a binary tree interview:

  • How do you find the lowest common ancestor of a binary tree in your preferred language?

  • Can you classify tree traversal algorithms?

  • How do inserting or deleting nodes affect a red-black tree?

  • What are some common ways to implement a priority queue?

  • What is a balanced tree, and why is it important?

  • What are some benefits of using a binary search tree instead of a hash table data structure?

  • How do you recover the original binary search tree if you have a binary search tree that's swapped nodes?

  • How do you determine if a given binary tree is indeed a binary search tree or not?

  • Can you update every key in the binary search tree to contain the sum of all greater keys?

  • Do you prefer building a binary tree from a postorder or preorder sequence?

Related: 12 Tough Interview Questions and Answers

Binary tree interview questions with sample answers

Employers ask different questions to learn vital information about applicants that may not appear on the resume. Consider some of these questions and answers for binary tree interviews to discover how to give your answers briefly and concisely:

1. Have you ever had a big challenge at work? How did you deal with it?

When an interviewer asks you this question, be straightforward and honest because challenges are commonplace in many work settings. The way you resolve challenges shows potential interviewers that you have the experience and willingness to handle diverse situations effectively. Keep your answer brief and only talk about the most important details. Remain professional throughout the entire interview and focus on solutions instead of discussing the challenges.

Example: "In my previous job, I was given two binary trees to check if they were structurally identical and if the nodes had the same value. This was very challenging for me, but I solved it by doing a preorder that traverses both trees while checking if the nodes on every tree are the same. I first used an iterative approach and then the recursive approach to solve the problem."

2. What can you tell us about a time you failed?

To answer this question, try to recall an absolute, actual failure and start your answer by clarifying to the interviewers how you define failure. You might explain failure as when you have several projects that you can't deliver on time or a challenging task that takes more time than usual to complete. Clarify the methods you choose that help you eventually succeed.

Example:While working on a project, I completely failed to create a binary tree from the given order and depth-first-search after numerous tries. Although the task's completion seemed futile at first, I continued looking for alternative solutions and asking for help from other colleagues. It wasn't long before a supervisor came to my workstation, and we discovered the data was erroneous. We started again from the beginning with the correct data and did the job within a few moments.”

Read more: Interview Question: "What Is Your Biggest Failure?"

3. How do you convert a binary tree to its sum?

Interviewers may ask this question to gauge your problem-solving and decision-making skills. The question also reveals the depth of your expertise and understanding of the job. When answering, give a detailed guide on how to perform the process to demonstrate your versatility in the field.

Example: “When given a binary tree, assume that the value of an empty child is zero, then replace each value of a node with the sum of all elements existing in its right and left subtree. Use a recursive approach to convert the right and left subtree, and then process a node using the tree traversal in a postorder manner. Update each node's value to the sum of elements in its right and left subtree before you revert the sum of every detail in the subtree rooted at the node from the function to calculate its value.”

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