CODING INTERVIEWS G U I D E: A Comprehensive Beginner's Guide to Learn the Realms of Coding Interviews and Top 150 Programming Questions and Solutions

By Olivia Miller

If this is your first time preparing for a coding interview, you will be somewhat overwhelmed. You are nervous, and rightly so.

Interviewers will hurl questions at you, expect you to write clean code on a whiteboard, and ask you to create an algorithm right there

and then. Honestly, unless this is not your first coding interviewer, y

• Language: English
• Publisher: Olivia Miller
• Release date: Oct 12, 2023
• ISBN: 9798868919886

Book preview

Introduction

If this is your first time preparing for a coding interview, you will be somewhat overwhelmed. You are nervous, and rightly so. Interviewers will hurl questions at you, expect you to write clean code on a whiteboard, and ask you to create an algorithm right there and then. Honestly, unless this is not your first coding interviewer, you should be nervous but think about this - everyone going for that interview is in the same boat as you are.

If you've done your homework, been through mock interviews, and practiced answering random questions until you are word perfect, you don't have a lot to worry about, but there are some things you can do to help you:

Write Your Code on Paper - when you attend your interview, you likely won't have a computer at your disposal. Instead, most interviewers will require you to write your code on paper or a whiteboard. Write all your code by hand on paper or invest in a whiteboard to prepare for this. Once you've done that, type your code into a computer exactly as you have written it. This serves two purposes - first, it prepares you for your interview environment, and second, it will highlight any errors. It is far easier for a programmer to use a computer, and having to write on paper can be a bit of an eyeopener. 

Learn Your Resume - technical skills will always be important, but your resume is too, so don't neglect it. Take some time to go over your resume and be prepared - you may be asked for a summary of a job or project you were involved in, and you may also be asked to talk about a tough problem you solved.

Never Memorize the Solutions - while this book promises to help you crack the coding interview, the questions are only a small sample of what you may be asked. There are, quite literally, thousands of potential questions, so use this book purely as a guide and do not make the mistake of memorizing the answers - the chances of you actually being asked these questions are small.

Talk Aloud - your interviewers want to know how you approach problems and how you think. While you are solving the problems, they set you, talk aloud. Let them hear your thought processes - often, how you approach a task is as important as the answer.

One last thing to remember - no interview is easy. Sure, you might get a few easy questions thrown your way, but you'll also get hard ones. Easy questions don't make it a given that you'll get the job. Being offered a coding job isn't just about being able to answer questions and solve problems; it's about doing it better than anyone else. If you get a tricky question, don't panic. Most likely, all the other candidates found it hard too.

You are about to embark on one of the most exciting journeys of your life. Preparing well will give you a great chance at getting the job of your dreams, but it will also help you learn a ton of new communication and technical skills.

Hard study and practice will make all the nerves disappear, so let's dive in and get started right away.

Chapter 1

Preparing for the Interview

So you need to prepare for an upcoming coding interview. You haven't a clue where to start, what to do, or what to focus on, but while this book will lay out everything you need to do, this chapter will focus on preparing for that interview.

What Is a Coding Interview?

A coding interview is a technical interview that assesses your competencies in software engineering with a view to landing a job at the end of it. Typically, these interviews are much the same as any other job interview, in that you will be asked questions and will have the opportunity to ask your own. However, they differ because you will be asked to solve some programming problems.

Most of the focus is on algorithms and data structures. However, other areas may be brought into the interview, depending on whether you are interviewing for an entry-level or more senior position.

Expect your interview to last around 30 to 45 minutes; they rarely last longer. The interviewer will give you one or more technical questions to answer, and you will be required to write code. Some interviewers will provide you with a virtual onsite coder to do this, but most will ask you to write it on a whiteboard. You must solve the problem/s within the allotted time.

How You Are Evaluated

The final chapter in this book will detail how candidates are scored during a coding interview. However, while techniques may differ from company to company, they will all use the following evaluation criteria:

Communication: you will be evaluated based on how clearly you ask clarifying questions and how you communicate your approach to a problem in a way that the interviewer understands you

Solving Problems: how well you understand the given problems and solve them with a systematic, logical, and accurate approach. You are also evaluated on whether you discuss potential approaches to solving the problem and how accurately you can determine and optimize space and time complexity.

Technical Competency: whether you can easily translate your solutions into code, using a clean implementation, and demonstrate a good working knowledge of how the programming language is constructed.

Testing: how you can test code against different cases and correct any issues that arise

The Best Way to Prepare for Your Interview

While plenty of resources online can help you prepare for your interview, it may not be a great use of your time. After all, most resources have thousands of questions, and you cannot possibly work your way through them all. The best approach is always a structured one:

1.  Choose a Programming Language

Unless a specific programming language is required, most interviews are structured in a way that suits most languages. It's best to choose the one you know well for your coding interview.

Languages suited to these interviews should be high-level with sufficient standard data structures and built-in library functions; these are the best coding languages, including Java, C++, Python, and JavaScript.

2.  Make a Plan and Stick to It

Plan your time accordingly and list out all the questions and topics in order of importance. How long you need to prepare for your interview depends on the level you prepare for. Typically, you should allocate around 30 hours total to cover the absolute minimum but if you want to be better prepared, expect it to take around 100 hours.

Start by calculating how long it is until your interview and how much time, realistically, you have to prepare in. Plan every topic you will cover each day and prioritize - don't forget, most questions are about algorithms and data structures.

For those that have plenty of time, try to spend a couple of hours per day over three months to ensure you are as prepared as you can be.

3.  Combine Study with Practice

To save time and ensure your brain can retain the information, move straight on to practice questions when you have studied a concept. Don't study every topic first because you'll have forgotten everything you learned by the time you get to the questions.

4.  Use Cheat Sheets

Cheat sheets are a great way to maximize what you learn and practice and should be used alongside your study time. Look for cheat sheets on the following strategies:

Techniques for coding interviews

Best practices for coding interviews

Cheat sheets on algorithms and data structures

Techniques for Coding Interviews

These cheat sheets provide you with several techniques to do the most important things needed in any coding interview: finding the right approach to solving a problem, determining space and time complexity, and optimizing it. These are particularly useful for encountering questions you've never come across before and getting you out of a hole when you are stuck.

Best Practices for Coding Interviews

As mentioned earlier, most tech companies use four criteria to evaluate interview candidates: communication, your ability to solve problems, technical competency, and testing abilities. Cheat sheets will give you guidance on what to do before your interview, during it, and after (more about this in a later chapter.

Algorithm and Data Structure Cheat Sheets

These will walk you through the best resources, questions to practice, and plenty of tips to help you learn and retain information on the important coding concepts.

5.  Prepare How to Introduce Yourself and Your Final Questions

These are two of the most important parts of an interview, and doing it right will leave your interviewers with a great impression of you. Take the time to write a good self-introduction and think hard about your final questions - these will be expected.

6.  Do Some Mock Coding Interviews

Interviews are nerve-wracking at the best of times, and coding interviews are among the most difficult. Try your hand at some mock coding interviews to give you some experience. You can find plenty of them online, and most are done with real software engineers who have been in your position.