This is a collection of coding challenges that I've solved, in preparation for coding interviews. I've also included some tips for acing your interview.
You can see a list of all the problems I have solved at https://bluprince13.com/apps/coding-interview-prep.
I know my preparation works because I was successful at the two on-site interviews I've had so far. For transparency, the first company did reject me due to my lack of work experience as a software developer, but they assured me they were happy with my interviews. I'm now a full stack web developer in London. You can check out my CV at bluprince13.com/cv.
I focus on Python and Rust in this repo. For a Java/Kotlin approach, checkout https://github.com/gravindran2412/coding-interview-prep
⚠️ I do not intend for you to actually read the code that I've written. It's not ultra efficient or well styled. My hope is just that seeing how I prepped for my interviews inspires you to do your own prep.
Challenges are grouped into folders by type, e.g., arrays, hash tables.
💁 I have also solved some coding puzzles for Advent of Code under the
adventofcodefolder. This was just for fun. The puzzles here are generally way harder and time consuming than what I'd expect in an interview.
One file per challenge. Links to the challenge, e.g. on HackerRank, are provided at the top of each file. Each file contains my solution, comments, and also unit tests to check the solution.
You probably won't need to write unit tests for your interview. I write them
because I'm too lazy to check my solutions manually. Laziness is a virtue. To
run the unit tests, just invoke the file with Python. For example,
python fizzbuzz.py.
The solutions are generally not as perfect as I'd like them to be. However, if you want me to explain a particular solution better, just ask me and I can polish it up. I'm a nice guy. 😛
Here are some good resources for preparing for the coding interview.
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HackerRank's interview preparation kit
Most of the problems I practised on are from here. However, I prefer working on my Mac with the VSCode editor. Therefore, I would solve the problems locally and then upload the solution to HackerRank once I thought it was ready.
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Grokking the Coding Interview: Patterns for Coding Questions
- Free alternative: 14 Patterns to Ace Any Coding Interview Question
Don't worry if you find some of the challenges really hard. There were plenty that I couldn't solve without looking for hints in other people's solutions. On some, I would spend an entire day trying to crack the puzzle! To be honest, knowing how to solve these coding challenges doesn't really help much in the day job as a programmer, but I do believe it's a reasonably good proxy for gauging a person's problem solving abilities / the way we think.
It's not enough to just be able to solve coding challenges. There are a few other topics that you need to be really familiar with. Listed below are some of these topics and links to learning resources that I recommend.
See Hacker Rank data structures playlist
See Sorting Algorithms YouTube playlist.
I can't stress how important it is to internalize this. Practice evaluating the complexity of your coding challenges until it's second nature to you.
Understand differences between these two types of databases and how you might go about choosing one or the other.
I'm not very good at these and I really struggled with the design questions that came my way. However, it's a very interesting subject and something that I'm excited about mastering in my programming career.
If you are applying for an entry level job, you may not need to prepare for this. Do confirm what the company expects from you for your interview.
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Grokking the System Design Interview
This is a paid resource, but it's the only one I came across that had good examples of System Design interview type questions. Highly recommended by moi.
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Grokking the Object Oriented Design Interview
- Free alternative: tssovi/grokking-the-object-oriented-design-interview
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Coding and system design interview questions (YouTube playlist)
I wasn't tested on this at any point, but I think it's good to have at least an awareness of what Agile is: a set of values and principles.
Normally in a coding interview, I forget that I'm interviewing and end up completely absorbed in the thrill of solving the problem. I think that's a good thing. Try to enjoy the experience and not worry too much. It's also okay to mess up as long as you keep your cool. Messing up obviously happens a lot in the day job, and seeing that you can handle it well will probably score you some brownie points.
It's also okay to fail. I have failed so many times that I have lost count. I have even done, and failed, interviews where I had no intention of joining the company, but I just wanted the practice so that I had a better chance of nailing the interviews that mattered. 😛 What doesn't kill you makes you stronger. 😃
Tweet me if this repo has been useful to you. 😃 I wish you all the best at your interviews and your programming career. May the force be with you. Don't be evil.