System Design Mock Interview: Design a Vending Machine

[@tryexponent]

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[@harisridhar1668]

This is the first time I've seen someone set up a state transition diagram for the lifecycle of an entity under discussion, and seeing the state machine discussed first stood out to me, since the majority of folks would immediately dive into fleshing out the HLD : High level design. I also liked his thinking a brief timeout period between inventory selection and payments processing : modern-day ATM systems also behave in a similar fashion, since a long-lived time interval between both systems could suggest payment fraud or faulty systems.

[@mikedqin]

Vending Machine is a perfect example of State Machine. I hope the interviewee can model the vending machine using state machine, which will be more better suited design in my opinion. Thank you for sharing. It's great.

[@tryexponent]

Great insight! We actually just posted another video on state machines right after this went live too!

[@nishant-s3v]

Had this question asked in interview & I hadn't prepared for it cause it's not the usual system design question. Went with it by past user experience of a basic machine & wrote the tables for it, but the interviewer was adding complexity by making this to be an online system & wasn't satisfied with any answers. I thought what else could I have added, but I watched this & had gone with the exact flow. Guess some interviewers are not so great.

[@jayashreebalakrishnan5772]

dispense change should be post success of dispense item? the concurrency requires a change?

[@pbhatsgw]

hash map should be used for low latency. Also, I thought this would be LLD/object oriented design but I see it's just flowchart and state diagram, is there a part 2 that's coming?

[@kishoregarapati1]

Can you tell me the drawing tool used in your videos? Thanks

[@kishoregarapati1]

it is whimsical

[@alexalannunes]

Best Channel

[@sagar1691]

Very nice video

[@긍정봇]

what is the drawing program in this mock interview?

[@tryexponent]

whimsical.com/

[@spiffyock]

What diagraming software is this?

[@tryexponent]

whimsical.com/

[@abhinay4200]

Head First Java used the State design pattern for this.

[@harshitkhandelwal8515]

It is more of a LLD Problem than a HLD problem

[@szyulian]

Watched. --

[@ankitsrivastav6363]

sorry but not good

[@shubhamAgrawal21]

Not at all helpfull !!

[@vinamrasangal8436]

what a rubbish !!

[@nameunknown007]

This interviewer is awfully quiet

[@lam_roger]

It's typical at large companies. The interviewee is expected to lead the conversation. I do wish interviews at large companies were more collaborative