Elevator System | Google SWE Teaches Low Level Design Episode 3

These elevators wish they have as many people entering them everyday as I do that's for sure

[Ms]

These intro's broooo 😭😭. Low key been always confused with the use of interfaces but this vid and the Cache design has cleared it up.

[Balaji-uzkp]

Thanks Barry Keoghan for taking time out of your busy acting job to teach us LLD

[muddassirbari]

🎯 Key Takeaways for quick navigation:

00:29 🛠️ *Low-level elevator system design involves multiple implementations, each with trade-offs, considering how elevators move through shafts and handle requests.*
01:23 🏢 *Elevator design can employ interfaces for multiple implementations, anticipating variations in how elevators decide their next move based on different systems.*
02:18 🔄 *Passive and active dispatcher systems differ in assigning elevator requests, impacting the interface between users and the elevator system.*
03:15 📋 *Methods like adding/removing elevator requests and handling unfulfilled requests are crucial in elevator system design.*
04:53 🛎️ *Including a button class depends on whether buttons hold states; in a basic system, passengers interact directly with the dispatcher to request rides.*
06:47 🧩 *Dispatch services are centralized; passing dependencies ensures coordination between elevators and dispatchers, even in large systems.*
08:00 ⚙️ *Naive elevator implementation focuses on handling one request at a time, potentially leading to redundant travel, especially with multiple passengers.*
09:39 📝 *Algorithm improvements could optimize elevator movement by iterating through open requests instead of floors, minimizing unnecessary stops.*
13:52 🧠 *Algorithmic enhancements like using a binary search tree can optimize elevator movement by quickly identifying relevant requests in a building with many floors.*
16:06 🚀 *Dispatcher service designs should aim for fairness, avoiding starvation of specific requests, possibly considering both time and distance traveled by elevators.*
19:09 🤔 *Dispatcher interfaces change based on systems where passengers input their destination floor, necessitating different heuristics for assigning elevators.*
20:20 🤯 *Elevator system design is open-ended, offering various implementations with different interfaces and algorithms, with no single universally optimal solution.*

Made with HARPA AI

[semperfiArs]

Congratulations on 5k bro. Deserve more man

[Itachi.Uchiha.Offical]

Finally an enjoyable video on this topic, thanks.

[xavierzhao]

FInally promises done! Waiting for parking lot and airport control😀

[beecal]

🤔 had been thinking about using enum to make some state machine for elevator, e.g. IDLE, MOVING_UP, MOVING_DOWN

[weizeng]

I feel like this is actually a multi-threaded solution. Because at least you would have a thread for the elevator cart and another one for the dispatcher. Otherwise the while loop in which you are checking for dispatch.has_unfilled_request is not too useful. Unless, all the request to the dispatcher were made before the elevator cart move() was called.

[TenCho-kk]

hahahhahahahahha. thank you for having no life, jordan. appreciate you.