Software Engineering Job Interview - Full Mock Interview

Technical programming interviews are challenging, but being able to do well is what lands you a job at a top tech company. Improve your interviewing skills by watching this mock full-length, real-world coding technical interview (OOP + dynamic programming) for a software engineering role.
Interviewer: @KeithGalli
Interviewee: @KylieYYing
The first half of the mock interview, Keith asks Kylie to use object-oriented programming (OOP) to design a reading application, given a library of books. In the second half of the interview, Keith asks Kylie a dynamic programming (DP) question trying to find the max length of the longest common substring in two strings.
⭐️ Contents ⭐️
00:00 Intro
01:26 Beginning the Interview
03:25 Object-Oriented Design Question
32:21 Dynamic Programming Algorithm Question
56:35 Feedback Chat
1:11:35 Closing Thoughts
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[@jheelgala6353]

This is pretty cool....but honestly I would cry if the interviewer started with , "Let's make a book application". I learned a lot today

[@paultvshow]

I think this is one of the easiest problems you can ask for.

[@bacon5481]

​@@paultvshow what's the next step up from this kind of question? Leetcode medium?

[@hassegawamkt]

I have one coming up Thursday. I've been told to use LeetCode and go for medium and hard challenges. A bit overwheliming TBH.@@bacon5481

[@Brian-ro7st]

This is about as cake an interview as you can have

[@spamgarbage6999]

I understand this all as she says it, but if I had to pull all this out of my brain in an interview Id cry or leave

[@benicia9408]

Same lol. Too much pressure

[@MrArkaneMage]

That's why CS50 ppl get a rubber duck to talk and explain to :) It does not only help with understanding but also being able to explain/recall something "on command" is an important skill to learn over time. In that case you are your own worst enemy you have to defeat in order to get the job. Unfortunately there is no way around this as it is expected to be able to function properly even under heavy pressure as this reflects daily business. It's hard to get if you are coming straight out of school/college/uni but you need to fix this if you want to create your own place in the working class.

[@11Khalid11]

As someone who is poor in programming, there is something beautiful in seeing someone program so eloquently, like how we write paragraphs for a nice essay.

[@bunnyman6321]

have you improved yet?

[@user-ff1fx9vq3m]

Do leetcode , read text books , leave tutorials

[@JamesballadMD]

I’m great with hardware but suck @ coding.

[@amanshekhar7200]

What should I do then😢

[@justin-cassidy]

Interviews like this are a breath of fresh air. I think being able to design a solution to solve a functional problem is a great skill set to have as a software engineer. I get so tired of seeing nothing but LeetCode type questions for software engineers. I’m not saying that solving those are easy, because they are very hard. But architecting a solution to a problem like in this video I find to be more pertinent to 99% of realistic situations in the business world.

[@rosspayne5099]

I have an honest question, Isn't everyone in the coding atmosphere going to be fucked because of AI? What is it that seperates a coder from a robot that can basicly do the same thing?

[@stanleyching123]

@@rosspayne5099what makes u think AI can solve this? Have u tried? AI can’t even solve my uni coursework and I’m in y1

[@rosspayne5099]

Because im seeing millions of people lose their jobs because of AI that are involved in similiar coding fields, and no dude i havnt tried it im not AI what kind of question is that ahahahah@@stanleyching123

[@utubewatcher806]

@@rosspayne5099 AI is comparable to the first language compilers and interpreters translating into machine language. These efforts produced mediocre to average code. AI delivers sub-par to modest regurgitated text and code from across the web. Code snippets rarely have references, so malicious actors can blog and tag for SEO supremacy, delivering malfunctioning and negative results.

[@schizo5189]

​@@rosspayne5099 Oh look. Another example of AI/crypto bro pseudo-intellectual archetype utterly failing to comprehend how the underlying mechanism of the tech they raved so much about even work in the first place.

[@ubikubik763]

Great video! I think it would also be great to see several people participate in the same interview. Thereby you could see how different individuals approach the same task.

[@ronaldoavich]

yeah, that would be interesting.

[@reecebygrave7211]

a perspective change would be fantastic.

[@franciscov511]

Regarding the dp problem does not have too many approches since it is a well known problem

[@chikensaregood9500]

i love that idea

[@unitygamingrio88]

That was brilliant, it brought back some memories of the interviews I've sat in and went through myself, outstanding job!

[@Kazner0h]

I'm so subscribed. What an amazing resource. I've watched a bunch of interview prep videos, but this one really helps put it all into context by performing it.

[@JetSoftProHQ]

Great job on delivering such insightful content! This video provides valuable insights for developers preparing for technical interviews.We truly appreciate the availability of resources like this that help candidates come well-prepared for their interviews. It's fantastic to see the community coming together to share knowledge and empower future employees. Keep up the great work!

[@UnhingedEgo]

I watch these whilst also learning Python too, so I can learn how to also communicate well when discussing thoughts and ideas.

[@omari6108]

This is extremely helpful. When I’m doing any kind of code it’s just for myself. I speak out loud what I’m trying to do, and have a notepad next to me, but coding a project for someone else does take a lot of fine tuning to understand exactly what they want. That requires real time communication.

[@licokr]

I haven't had interviews in English and the video is really helpful for me. I've never had interviews like this, so, I'm really nervous cause I'm preparing for interviews now. Thank you! "Don't write down without saying anything" I will keep it in my mind!

[@GuitarHope]

This is awesome. Thank you so much for uploading such priceless contents.

[@kirk7880]

I love this. One soft suggestion is including a quick intro. I think that just reinforce a critical step in the process

[@SnapshotsOfHistory1]

This video just killed my desire to be a software developer

[@daughteroftheking3220]

Fr😂😂 imagine doing this in an interview real time I would literally just be lost and the pressure of time/my anxiety would get the best of me. I would just give up and exist out of the interview room right then and there and not look back.

[@SteveMorrow8859]

It's like being a fly on the wall of another interviewer, seeing the questions asked, solutions proposed, and feedback provided. This has changed the course of my life and in how I plan to solve problems moving forward. Great video!

[@arkprince9413]

that first question hit the spot exactly what i am lacking for years i want more

[@debbie_bae]

I just love Kylie's workflow and mental clarity!

[@Khadi-C]

Later this year, I will start a bachelor's in software engineering. I definitely need this!

[@Adam-kk7nw]

Just lie and say ur transgender and non binary they won't turn you down no matter what if u failed the test

[@lonewolf.8635]

Lol

[@kiidpoh]

​@@Adam-kk7nw 💀💀yk what this is probably true too especially in places like san fran

[@Stephen.c19]

@@Adam-kk7nw modern problem require modern solution lmao

[@Adam-kk7nw]

@@Stephen.c19 this made my whole day 😂 thank you

[@countremy730]

thank you for taking us along on this invaluable resource. More please if you are able. If not, I completely understand.

[@Plasma_King]

Wow i actually find this challenging, but very interesting! Thank you for giving me an insight of how technical interviews are done! I actually thought it was a lot harder where they observe you on how to build it from scratch and make it work in the end!

[@VGBNDGRL]

Yeah, this was very cool to see, and quite challenging when your perspective on interviews is to ace them. I think what was most important here, is that the candidate explained her thought process out loud every single step of the way, so that the interviewer can follow along 100%, and even if the interviewer starts to not follow, maybe ask every now and then if it makes sense. I think I feel more confident after seeing this video bc it proves that interviews should be a conversation on implementation, drawbacks, pros, larger questions, modularity, and less on getting a right answer...because designing a system isn't something you can get right 100% in the real world.

[@shishenliart]

Learned so much from this video. I am a fledgling programmer (just started taking the 200-series programming classes) still trying to learn a language and practice my logic building skills and this helped tremendously.

[@omgmaw]

Great video. I learned a lot of news tips and tricks on how to approach a technical interview.

[@shockearth4295]

This held my attention from start to finish! I like how she was explaining her thought process while she was writing the lines of code. It was fairly easy to follow along.

[@emperor8716]

that's what you're supposed to do. if you're just quietly writing code, the interviewer's gonna fail you whether your program works or not. they mainly ask these to hear your thought process of how you solve problems.

[@faraaz3414]

Awesome!!!! Please bring more of these.....

[@olesiacheban2054]

I actually did do a follow-up after the interview once. It was my first job and I had to present my pet project.. and it did not load.. for the whole hour and a half I was trying to run it in parallel answering tech questions, but no luck. After I finished the interview I had reloaded the laptop and the project ran okay, so I made a video of it working and sent it to the interviewers. I got the job!

[@honeydevaang732]

This is not just for the interview things, but also the code structure that was implemented so smoothly. Everything just looked like a roadmap👌👌👌👌👌👌

[@rosspayne5099]

Isn't Everyone in the coding department going to be fucked hard because of AI ? Honest question, what seperates someone who can write code and a robot who can do the same thing?

[@mrnobody1546]

​@@rosspayne5099most probably, but my lecturer told us to embrace it, AI is inevitable, so we must learn to use it efficiently

[@MK-rx2fj]

​@rosspayne5099 a bot writes code for instructions you give and you edit parts of that therfore your productivity is higher

[@YouTube_MusicStyle]

​@rosspayne5099 , AI to coders is like Tractors to Farmers. Useful tool to handle things efficiently but without the farmer the overall job doesn't get done.

[@KaioRosa]

This is fantastic!! I loved it!!!

[@bloodorangebrisktea87]

Thank you for making this mock interview!

[@Yeard491]

Been looking for this exact thing for AGES. Awesome!

[@j_a.0]

Im literally not even in uni yet, and i want to do computer science. Im doing maths a level right now, and watching this has gotten me so exicted because it truely is its own language. Ive also always loved solving problems that can have multiple unique ways of getting the same result (hence why i love maths), and ive just realised coding is that exact same thing!!!

[@UnfinishedYara]

Keep it up!! Your intrest alone is a great quality to have!

[@nocopyrightgameplaystockvi231]

The use of Lists was actually pretty cool. I was thinking of a JSON array, but then Lists are kind of way more powerful due to their incredibly useful methods and as said in Head First Python book, "Lists are arrays on Steroids". Nice Mock Interview. I just want these to go on.

[@onemoregodrejected9369]

If you are told to use python, you gotta ABUSE the hell out of lists!

[@nocopyrightgameplaystockvi231]

@@onemoregodrejected9369 damn yes. LISTS are for abuses 🤣🤣🤣🤣 without regrets.

[@thisismyplaylist]

yep I added that to my background

[@anon-fz2bo]

yea when they said 'collection' of Books I automatically defaulted to std::vector or Vec or []Book or even Book* if ur feeling fancy and want to use a static array

[@nocopyrightgameplaystockvi231]

@@anon-fz2bo pointers 😂 not unless it's mentioned.

[@seshank144]

The answer for the follow question regarding font size feature was just awesome

[@amortalbeing]

side note: 9:21 dictionaries are ordered since python 3.6. regardless if you'd want an ordered dictionary, you have always have the ordered_dict as an option!

[@prism_schism]

Okay, I realize software engineering IS for me😂 loved the discussion, and looking forward to talking CS with people.

[@RamiroAsincrono]

Thank you for this excellent mock interview!

[@jaretsanchez1900]

I've been working as a developer for a year now and it's very humbling how she can mention these best data types to provide for these objects. Things like dictionary objects are still new to me.

[@franciscov511]

It is basically a hash map, in python it is called dictionary

[@sidgillespie5879]

Keep in mind this video is staged.

[@mattlau]

This is an incredible video! Thank you!

[@DiegoXMV]

this was pretty mindblowing, and looking to switch companies has eye opening. I really need to work on my algo game for the interviews

[@dave_di]

This man is a beast with data.

[@adrianmargean3402]

i don't have enough words to thank you for this video!

[@dextercalayo]

Awesome content. Thank you!

[@lilyou2219]

I am so jealous about how Kylie been able to express her thinking process this clearly and how quickly she came up with the solution. How long will it take to be as good as her?

[@passiongotways1286]

Just be you

[@Haise-san]

Some good practice time doing explanations while you're solving a problem coding, soon enough it will become hardwired in your brain.

[@optimistiks]

you should be much better if you want to get to faang, there you are expected to solve two leetcode hards in ~40 minutes, and this dp task was at most medium

[@memaimu]

A CS as your first and only degree and a passion mainly for programming for the better half of your life.

[@gbswann]

I have been wanting to be able to sit there and watch a person code while they explain what they are doing because it is important to see how people are thinking through things for me to learn to code.

[@sixstanger00]

I never understood the point of technical interviews "testing your coding ability." Nearly all programmers will have a portfolio showing what they're capable of. I shouldn't have do it again under the gun just to back up my portfolio. If you're going to test my skill in a technical interview, don't ask for a portfolio.

[@user-pl6hy3km6s]

true but they also want to make sure you haven't just copied others people work, and they also want to see how you handle under pressure

[@sixstanger00]

@@user-pl6hy3km6s *_true but they also want to make sure you haven't just copied others people work_* If this is the reason, then every software engineer in the field needs to be fired. I don't know of any software engineer who hasn't at some point referred to StackOverflow for snippets of code. It's inefficient to expect coders to rewrite code that already exists, especially if it's going to serve the exact same function. Even if the coder DOESN'T copy it from someone else, the CODE will still end up looking identical (apart from perhaps var names) because languages like Java, JS, CSS, Python, etc will only work if code is written one way. *_and they also want to see how you handle under pressure_* Yet again, this is a pointless test. Nearly any job is going to put the worker under pressure at some point. People apply for jobs EXPECTING to be under pressure occasionally. If they knew they couldn't handle the pressure, they wouldn't be applying.

[@Sinnerage]

As someone who’s only a few weeks into my coding journey I’ll have to come back to this when I have a better idea of what she’s coding, I understand some of it but a lot of this like hieroglyphics lol. Awesome job tho and very cool to watch.

[@tjames22123]

Great mock interview! Thanks for the tips :)

[@zebra00024]

It was actually very good, both sides are very professional 👍 Excellent examples.

[@_Anna_Nass_]

This is top tier content. I love hearing her explain her thinking process. Thank you freecodecamp!

[@OMFGTrexKyle]

I agree. Kinda annoying how he kept talking over her

[@Platcode797]

​@@OMFGTrexKyleig interviewer can do that, so it's good

[@BrendanAbolivier]

As someone who've been on both end of interviewing, verbalising your thought process is very important in an interview - and Kylie Ying did great in that regard here. It's better to overshare about what's going through your mind (as long as it's still related to the matter of the interview 😛) than the opposite; if you're completely silent and suddenly stop doing anything, the interviewer can't read your mind to tell if you're just taking a break to think better about your solution, or if you're completely lost and don't know how to ask for help.

[@ExploreTUlearn]

Wow! She is so good and confident.

[@surkewrasoul4711]

This was just awesome. 😊

[@dylanheslop9161]

Awesome! I haven't wateched it fully yet but I think it will be perfect if we code with her and actually answer and format our answer while she does the same Thats what Im gonna do

[@masongkrause7]

In the library class, the collection of books should be a dictionary from Book : active_page_number, that way a users library would be full of books and the page they're open too, along with an active book. That was what the interviewer asked about too! Just in case anyone else was wondering.

[@rvzgar]

very educative and professional, made me excited already.

[@manfrombritain6816]

4:45 haha i basically made this exact thing for my own fun project to promote a book i wrote. i chose to implement the "display page" thing by writing a script that would get the next X words in the entire book - where it would estimate an average number of words per line and number of lines per page, then try to fetch as near as possible to Lines * WordsPerLine - rounding down. it worked pretty well so that page numbers could be independent from the book content, however it would often leave you mid-sentence with a bit of a gap before the end of the line which would look a bit weird.

[@CesarRodriguez-nb2lm]

Amazing content as always...

[@Seremothgr]

Great, now some way to handle the crippling interview anxiety.

[@thegamerteo0560]

currently doing btec in computer science, this vid helped me a lott

[@antonioaugilar168]

Just finished the first semester of python and all of this makes sense.

[@vcool]

Instead of giving dynamic programming exercises that are completely irrelevant to the job, interviewers should make the effort to come up with more realistic problems have some connection to the job.

[@SierraFulminare]

wait i love this, thank you so much for the video

[@JS-ii3rn]

Great job! I’ve just noticed that you introduced some difficulty maintaining the code and ambiguity in the add_book_to_collection(). Instead of Passing in the arguments manually, passing in a finished book object brings benefits like avoiding duplicates, avoiding invalid states or changing Book in the future.

[@bigsmoke4568]

That keyboard sounds heavenly! 👌

[@tallerdenyooh]

Going character by character to detect for plagiarism between two books sounds over the top. Have a globalSum var that keeps track of the highest number of common words between books. Indincies is a tulple that caches the indexes of the two books that globalSum comes from. Before going character by character, I’d have an array of objects for each book where the keys are the individual words in each book and the values are the number of occurrences the word shows up in the book. Then iterate over the array from i ==> [0, n-1) and iterate over the keys in array[i]. If the key is found in array[i +1] then add the minimum value between the two objects to currentCount. When we’ve finished checking all the keys, compare if currentSum > globalSum, then update globalSum to currentSum and indexes to [i, i +1] Return indexes when we’re done iterating over the array of word_count_objects

[@sureshchakma5492]

❤❤❤ just awesome interview

[@qghungluu5757]

damn, she's so good at speaking thoughts and exchanging information

[@quimalabs]

Start by creating a diagram class and defining object relations. Then, implement the diagram class code and share it with your interviewer.

[@marcus47_]

Started Python a couple weeks ago, was interesting to see the way the scenarios were dealt with considering I don't even really know how classes even work yet lol

[@stephan4804]

I'm in my second semester of OOP and I still struggle wrapping my head around things like class relationships. I think Most intelligent people if they put the effort in could understand what methods and instances of a classes are. However, to fully understand classes, you need a deeper understanding of object-oriented principles. Now I don't believe most people would comprehend concepts like abstraction, encapsulation, inheritance, and polymorphism etc... Its a very deep and complex topic that takes practice and practice.

[@ontoshere]

I know this is a bit late, but the easiest way I found to understand classes was to, just a coincidence here, but think of them as books. A book has key elements to it, author, the content, published date, isbn etc, and those would be enforceable properties of a class, things that make the object, the object, in this case a book, a book. Right? Then inside a book, has chapters, think of those as methods, every chapter provides a function regarding the book, chapter 1 for example uses the content and starts the process of moving the story forward, while maybe chapter 6 is needed to develop a character a bit more, and all that information is there for you to reference. Think of that as class.method. You need to know about that guy from chapter 6? book.chapter6() will provide that for you. Now you have the blueprint of a book, all you have to do is initialize the object and pass it what it needs, write the author down, write the content, etc. Book hp= new Book(author, content, isbn, etc) and you can crack that thing open whenever you need to now to access it's contents, again, hp.chapter6(). Or a more realistic example hp.length() and your length method would just be like ```return len(self.content)``` using python. And to add on to that, for inheritance like above, book maybe more of a broad class if you will, but then maybe you want a short story class with the same type of functions as the book class. There's where inheritance comes in. The book class can be used as a parent of the short story class, where the short story has copied the over structure of a book, but it's still it's own separate thing so it can have some specialized methods as well. I'd keep going but I think you get the jist. It doesn't work great for encapsulation, but just wrapping your head around classes and understanding their purpose opens a lot more possibilities for comprehension for the other concepts.

[@smarch3912]

As a noob who literally started my journey yesterday I understood nothing, but it's pretty cool to see what someone who already knows her stuff looks like. Hopefully when I come back in a few months eveything she is saying and doing will make sense to me. So far I'm loving it, though.

[@michaelaguilar1750]

What age are you starting?

[@Fran-kc2gu]

you are learning in the worst date, interviews are wild now

[@Florida_man21]

​@Fran-kc2gu I know, I wish I started to code when I was a new born

[@saidibrahim5931]

Please make more videos like this

[@paco5star]

I must be closer to my goal then I think because I was able to build this particular assignment very easily I’ve been learning programming for a year and a half now about to start the job search soon!

[@chickenlittle4344]

Thats great to here! I am on the other side of the spectrum lol. I am learning CSS and HTML 😢 This turns my world upside down. I wish my MIS BS taught me more.

[@drickascorner]

@@chickenlittle4344 lol same just started learning! we will get there.

[@lalodominguez7121]

she handled that no problem 🔥

[@angelg3642]

Thank you very much for taking the time for the test and the technical interview. Unfortunately, we cannot offer you the position at this stage, but let's keep in touch for future opportunities. I wish you success and the best realization in your career, don't give up, you have great potential for development.

[@TheQuancy]

After doing a lot of leetcode and have been destroyed by edge cases. Not adding an edge case for page turning and out of bounds index error is killing me

[@hidoryy]

failing because of edge cases in leetcode makes me feel really stupid because usually you just need to add a single if statement to pass the test

[@sweetphilly2]

lol ol' boy traumatized

[@usman-ali0]

This channel is GOAT 🐐❤

[@48_subhambanerjee22]

This felt so amazing

[@Wts185]

This is crazy it’s this really a mockup for fresh grad developer

[@johnbruder4519]

Great stuff Olivier!

[@davinkyy6723]

I have a couple questions for the book and library classes. 1. when the code is ran are you intending to make a object from book and then adding it into the collection 2. when adding to the library collection can you just do this self.collection[self.idcount]= book ## book would be the object you made from book also based on this you would only need 1 counter in the library that sets a id to a book when inputed into the libraray

[@shreesivlogs]

great mock interview, i love this video.....🙂

[@yuikozhang5650]

She is so young, so beautiful and so organized. Thank you for this amazing demostration.

[@naveensaicremsiyadlapalli3769]

Genuine Interview

[@randy4ii411]

I am not sure if you know this or not Kylie but poppy lee in Mythic Quest must be you cause you look exactly like her, especially when you wear the specs. Amazing.

[@codingsingh4156]

there can be many active books.. a map with mapping between string and boolean makes sense.

[@exmachina767]

Why not just a list of active book ids per user?

[@younggamerham517]

I wouldn’t be able to explain it and talk as good as her, but at least I also had the same concept going through this and slightly a bit different ways to go about making stuff! Other than that great lesson

[@izaiahevans6989]

Thank you so much, this will help me apply for a job as a software engineer next Month.

[@paolajimenez979]

How’s your interview went ?

[@izaiahevans6989]

@@paolajimenez979 Searching still, jobs are being taken. No interview yet.

[@nguyenthanhlong5963]

awesome, thank you for sharing :3

[@Jujuh-000]

Dude, keep it up!

[@CertificationTerminal]

Much appreciated!

[@rabiaedaylmaz1198]

Wow, than you so much!!

[@strideredz]

Just starting my coding journey and all I got from this is "Is there Adele" 21:07 I got a long way to go

[@MEX_TECH]

It was all very exact and direct

[@amg4455]

Thank you❤

[@VictorPanainte]

Great content big thanks

[@skyclean5020]

Great Video! one concern here. Active book and last page will not be different for each user?

[@KingstonFortune]

this is really good stuff! kudos to the team for putting this together... I noticed one thing tho, at 11:28 I figured she could have used ISBN instead of ID, as ISBN is the unique number for every book. I love that she used list for the pages too.

[@kinuly1174]

Unfortunately, like the interviewer said, this is for indie works, and are not necessary all registered to the ISBN system. An ID system would be more robust in this case, but I like that idea!

[@alexeisosin9203]

there 's also a limitation that ISBN was only introduced in 70's so basically all antique books are ruled out, but ISBN option should have definetely been discussed, and it didn't

[@alexeisosin9203]

@@kinuly1174 sorry, no printed book can be sold without ISBN. Are you talking about articles, not books? or something like github "books"?

[@LinuxUser123]

@@alexeisosin9203 I think it was like custom books that the user can create, not officially with a registered ISBN but they mentioned they need to give it a Title, so I think it's users own book

[@rookieEngineer]

I think she was trying to giving an ID to multiple same books since isbn would be same for all these that would not work. As she said in the real world it would be not ideal to assume there isn't multiple copies of the same book. Giving an ID by the way the books are added to the library gives each book a uniqueness

[@deluxebulls5939]

damn i got a loooong way to go! ha! I knew that already but seeing this really makes it hit home. Just gotta take it one day at a time!

[@user-tt7po9td3x]

Being a JS developer, I’ve always loved Python for its concise code

[@heatherandsharada]

Thank you!

[@deniowork7084]

Love this!

[@Ninjaah_]

i am never getting a job

[@chrislaneyjewell6743]

Create the Job bro !

[@attitude2492]

Yes you will