Layer 3 · Go deeper · 8 min
Go deeper
Size it, build it, then make the calls an interviewer will push you on.
Back of the envelope
Size it up
Tap through each step of the arithmetic.
What does a photo inside the JSON body cost?
What do five sequential calls cost on a phone?
How do you spend five minutes on the API step?
Build-up · 6 steps
Run the recipe on tatkal booking
A tatkal quota opens at 10:00 and a crowd far bigger than the quota tries to book. Six steps turn the requirements into a contract.
Step 1 of 6
Read back the requirements
Start from the functional requirements you already wrote. A tatkal booking system has five things users must do.
4 interview moments
You’re the candidate
The interviewer pushes on the hard parts. Pick an approach and see how it holds up.
Deep dive 1 of 4
Interviewer
“The interviewer asks for the API. You have about five minutes. How do you spend them?”
Your move. Pick an approach:
Deep dive 2 of 4
Interviewer
“How do you expose “cancel a booking”, which also triggers a refund?”
Your move. Pick an approach:
Deep dive 3 of 4
Interviewer
“Your URL shortener answers GET /{code} with a redirect. 301 or 302?”
Your move. Pick an approach:
Deep dive 4 of 4
Interviewer
“500,000 online drivers send a location fix every 4 seconds. How do the fixes reach you?”
Your move. Pick an approach: