Low Level Design of a Fitness App and Mock LLD interview with Intuit SWE @Keerti Purswani

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[@rajangarg8748]

Very chaotic discussion. A lot of decisions made by the candidate didn't make sense, but interviewer always replied make sense to everything.

[@vasudevjamwal]

this is the most authentic comment I see here

[@dalliravitejareddy3089]

@@vasudevjamwalauthentic cuz he’s trying to be contrarian. But it’s not a fact. It’s subjective

[@sanyammalik6239]

I agree no of steps is a part of metric not goals. a metric will be different from goal but goal should have 1:1 mapping(join) with the metric.

[@ConfidentCoder]

i stumbled up on this somehow and saw how dumb this interview was

[@cristianouzumaki2455]

They were probably planning for the interview to go all day so that by night they could reach the actual implementation

[@KeertiPurswani]

Thank you for having me Yogita. Such an honor ❤️ Plus got to have so much fun ❤️❤️😇😇

[@sudocode]

Video on Keerti's channel where she interviewed me: kzbin.info/www/bejne/maLboKqXZa-Vpqs Hello people, The very talented Keerti Purswani has shared her time with us by solving a LLD problem of designing a fitness app. Please note this is a mock live interview which means Keerti didn't know about the question until we pressed record. Her attempt to solve the problem is absolutely natural and how it happens in a real interview. There might be multiple ways of solving this problem and you can share how you would have solved it. Both Keerti and I will be open for constructive feedback but I request you guys to type with kindness. This is an experiment and many of you requested for such mock interviews and we are trying the same. We sincerely hope that you derive some value from this LLD mock interview video.

[@varunbhatt8761]

Great efforts by both. Few suggestions 1) matrics and goals don't seem related so I don't see a point of having common interface. 2) in user class to store goals, you could have considered list instead of vector as it will be better in case of delete and generally we will anyways traverse through complete list so random access of vector doesn't help much. At least consider the trade offs. 3) I don't see a point of config class. Generally configs are maintained in the ini or config files so that you can just change the value and it will work without having to compile the binaries every time we just change the value of any config option. 4) as notification was discussed in much detail in the requirements part, you should have touched upon it. Having one common interface INotifier and different notifiers(msg, email, push notifications) derived from it and using some kind of event subscription mechanism to handle notifications.

[@sudocode]

Good points!

[@akshayshah8264]

Excellent problem statement and great effort by both to give a feel of LLD interview. Few suggestions: 1. I think the main component should have been analytics, whereas the discussion revolved a lot around Goals, configuration etc. 2. The key requirement was to know how the device would give data. In what format it would give data, as this will influence the entire analytics calculation for weekly, daily, etc and also classes. I think this should have got clarified from the interview before starting with classes. 3. I don't see a relation between goals and metrics directly. A goal is just a placeholder for target, progress, reward point, etc. It should have been associated with a class like AnalyticsManager which knows that a particular metric should update goal values.

[@Intimationinc]

I don't see a solution here, its just requirement collection

[@ChandraShekhar-by3cd]

Thanks a lot for starting the LLD series , really liked the way of interaction to solve these problems. These videos are quite helpful. Could you please start LLD and HLD series as well on designing UBER, Whatsapp, facebook etc like open ended problems. Thanks

[@sudocode]

Most welcome! Yes will be starting those mock interviews soon.

[@ChandraShekhar-by3cd]

@@sudocode Thank you so much! I have watched all of your content and it really helped me in understanding the topics in great details. Your explanation on any topic is quite insightful.

[@ak9tgaming714]

Hey there, I appreciate the amount of effort which was taken in making the video however there are certain approaches which need to be followed instead of jumping onto solutions after gathering requirement: (Usually in MNC product based companies, interviewers expect candidates to follow the following approach during LLD round - iOS/Backend) - Requirement Gathering - Reiterate the requirements by jotting down use cases - Define what would be the core actors & helpers - Create a use case diagram that defines your use-case as an overview - You can now create an Activity diagram to define the flow - Now to go in depth, this is where the real LLD starts, you'll have to create ER diagram (entity relationship diagram that represents the classes its properties and methods present inside every block.) PS: We can also call out that we are not going to take care of sharding or load balancing as it's assumed that it's already been taken care of which doesn't comes under the scope of iOS, for backend you've to cover theses aspects as well which are missed in iOS)

[@eshanjain1315]

waiting for LLD course thank you so much for creating and help the community

[@exodus5948]

Hi Yogita mam, Saw your videos multiple times and my understanding of a system has been levelled up. Thanks for all your contribution.

[@sudocode]

You are most welcome

[@UntamedRogueMavrick]

Great discussion!! Even though toughest LLD problem I have ever seen. Would never want to have in any interview.

[@sudocode]

Haha

[@vikaskad5737]

That’s good conversation, I learned so many things from this video.

[@yogeshdharya3857]

For the first 5 - 10 minutes I thought it is you who is giving the interview to Keerti

[@vipinraip1207]

1. Can't we make Goal an interface and let HeartBeat, Steps, Water Intake,.... implement it? Goal can have { Status, Reward, Metric,.....} 2. We could also have an interface Metric and have implementations like HeartBeatMetric, StepMetric,.....? ( Metric is part of Goal )

[@ishikajain9676]

Agree

[@vaibhavmehta36]

Informative !!! Please start this as a weekly series.

[@alphacoder3822]

A SDE2 is interviewing a Senior Software Engineer damn keerthi ma'am was so humble and she acted like she's really giving an interview. Now the problem is Ab mujhe preparation karna hai bhay

[@sudocode]

Sorry to disappoint to you but I am Senior Software Engineer in this case, however if you want to see the SDE 2 interview an SSE, you can head over to Keerti's channel where she has interviewed me. All the best for your prep. :)

[@anandyadav_]

Should we intensionally do ask to add features? Won't this make the interview a bit difficult

[@sudocode]

No it won't. Your interviewers will say yes or no as per what they need to test but asking questions around requirements is always helpful.

[@anandyadav_]

@@sudocode okay!!

[@devarajchennur9911]

Thanks for this 👍👍👍👍. You are rocking ji..

[@PkSam07]

There should be a further lld video on the same app to know what we left and then what else could be improved on.

[@sayalii_shelke]

The requirements consumed a lot of time. Maybe they could have just reduced the number of requirements and focus more on how to actually code for LLD. Focusing on one component would have helped here.

[@leetcodebaby6680]

I don't get the ideas of interfaces generally like How did they figure it out that Analytics has to be a Interface and not a class?

[@sheshitkarthikeya1528]

Kudos to the editing and great audio!! very well done. generally these mock interviews have very bad audio.

[@NidhiKumari-vu3oj]

Hi Yogita,Keerti, Thanks for posting this ,I really liked this video and honestly saying previously I had 1-2 system design interview and i was so so nervous that what will happen, the interviewer by then were very helpful like you were here. After watching this video I got a lot of confidence and would like to request you to post more videos that can have a proper relationship in a class diagram along with the code examples. Thanks Nidhi

[@NaukiKumar]

Watching this video a day before my LLD interview. Fingers crossed🤞

[@sumalyasaha]

Great conversation.I would like to suggest that we can keep the metrics as separate from goals and a goal should be an observer of an observable metric using observer pattern and hence can update its progress and status.

[@venugopalreddy6618]

Thanks, Yogita for the wonderful free content.

[@SaptadeepDutta_Ex-Xerox]

12:32 Wow! 'Class' mentioned by a millennial, use of which in designs seems to be gradually disappearing. I dabbled in UML/OOAD stuff and any mention of OOAD vocab. has me excited. Great LLD, by the way. Appreciate.

[@vamshilyyfelog]

One month into your channel and i am already learning a lot

[@akashbhadouria6727]

Waah ma'am thanks a lot. May you get all the success🏆💪 and love ❤in your life. Thank you again 🙏

[@ShivaSomapur]

Instead of the desktop app polling for data at regular intervals, the tracker can send the delta of data accumulated between two sync cycles.

[@sudocode]

very valid point!

[@soumyaripan5131]

This is a great interview.

[@starboy_jb]

Good to see that question was not out already 😀

[@bharadwajpoduri3349]

I did not understand the Config class. I mean if we take unordered map with ,where are we storing the actual config values?

[@bharadwajpoduri3349]

By the way great video, thank you so much and would love to see more such mock interviews on this channel Yogita👍

[@amishsumit]

Too much of requirement gathering discussion in the beginning. It makes the video little off-colour. LLD should be straight to the point and as and when the things start getting complicated, interviewer should have a chance to spice it up a little and dig deep through it.Somewhere I felt Keerti was in project maintenance mode.

[@TarequeMdKhan]

Totally agree. Generally candidate should drive the answer, but the initial 10-12 mins, it was reverse. And candidate should do more talking.

[@mohammedajazquadri7869]

MAKE VIDEO ON DESING PATTERN SPECIALY LIKE SOLID,FACTORY,SINGLETEON,FRONT CONTROLLER

[@amitsatpathy07]

Just one suggestion Yogita, If you are planning for more such mock interviews in near future, you can add one 5 or 10 sec pause moment feature in video after you share your question with interviewee as it would help the viewers to think for solution themselves. Nonetheless, we do have pause option, which would work just fine but it's more of a value addition for viewers, so thought of sharing my view. Loved your content.

[@sudocode]

Thanks a lot Amit. That's a really useful suggestion 😅

[@AdityaRajVerma]

awesome

[@sunilpingale2414]

Could you make one full HLD and LLD video on UPI payment. How to design PhonPe, bharatpat.

[@srikantht890]

Hi Mam, please make video on designing high available distributed cron scheduler. Thanks in Advance

[@sudocode]

thanks for the idea. let me research and come up with it.

[@mukeshbisht2411]

very real mock interview

[@mayukh_]

How come it’s an lld?

[@cut-a-lyst]

For me, heart beat is not an activity. I would rather have metrics class separately and another class activity that holds goal object and metrics object.

[@sudocode]

That's a good way to go about it.

[@nikcsm]

Amazing video, and amazing comments alot to learn for me XD

[@badbaboye]

Great mock-up

[@GRIEFify]

Appreciated the efforts for the uplift of engineers like me. But, in real-time, Interviewer won't be answering/suggest so much and they just will say design health track app for reporting and sit idle. More questions we ask; they will judge us as not capable of assessing big picture and will have a negative image in his mindset. Result - rejected

[@VikramKumar-qo3rg]

I do not have much experience myself. But I feel asking more questions wouldn't be considered a sin. However, the quality of your question is something that you'll be judged upon. Clarifying the requirements and the solutioning is always a good sign as long as the questions are not dumb.

[@ConfidentCoder]

[@TheDiscreet]

Very good design conversation.. Helps in approaching the problem.. Recommended books for LLD would be helpful...

[@sudocode]

You can check this out if it helps - kzbin.info/www/bejne/a5XUp5V6gtSXotk

[@TheDiscreet]

@@sudocode Yes i saw it.. I thought it was for system design only

[@basawarajshivashetty]

Do we need not draw proper class uml diagrams during the interview.. explaining the relationships between classes is enough?

[@sudocode]

We may or may not depending on what interviewer is looking for but it was hard do to it in 45 minute video.

[@basawarajshivashetty]

@@sudocode thanks!

[@narenshalivahana1111]

keerti did it more complicated and wasting time.

[@viktoryialinkevich9925]

For which position this interview was conducted?

[@sudocode]

Software engineer.

[@abhimanyuarora9262]

less interactive. looks like a boring college lecture where no one is smiling, showing energy or enthusiasm. like doing just for the sake of it. should learn from other creators.

[@sudocode]

I didn’t know we were supposed to entertain while educating. Will definitely keep this in mind 😉

[@SunilSharma-mb2kf]

Is LLD important for freshers as well? 2021 batch.

[@ChandanKumar-rl6df]

For Freshers, LLD is not required.

[@runningFun]

It’s gr8 to see good conversation between 2 girls...

[@shivamkamal2709]

Please make video on load balancing also your videos are Great

[@sudocode]

Already done did you check SD playlist?

[@shivamkamal2709]

Yes checked but didn't get 😕🤒

[@shashankjoshi2475]

From madhya pradesh?

[@amitsatpathy07]

She is from a place called INDIA.

[@shashankjoshi2475]

@@amitsatpathy07 read channel about section....

[@sudocode]

Not to spoil any one of your moods, @shashank joshi, where did we mention Madhya Pradesh? and yes both of us from Madhya Pradesh and also we are proud Indians. So peace out. :)

[@Tyrus429]

Keerti seems to be very confused...yogita knowledge is over powering her. Thanks but try to make videos which are crisps, even if you solely take a topic and tell us how to system design it that would be of great help. U r really a gem, and we adore you Yogita. Thanks

[@TheSheldorAFK]

mam is there a way to marry you. so that i don't have to hire systems expert for my company. jk

[@sudocode]

LOL. I would still charge after being married but I sadly for you I am already married ;)

[@TheSheldorAFK]

@@sudocode ❤️

[@ashwin1998-w5i]

dont mess , u could do it in better way. try to use digital note pad , some content is not visible

[@TarequeMdKhan]

I respectfully disagree with the whatever was shown.