Art of Codeartofcode
Lesson 16 of 21

1. How to Approach a Design Question

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The picture to keep in your head
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1.1 What is a system design interview, and what isn't it?
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1.2 What is the interviewer actually scoring?
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1.3 What's the step-by-step framework?
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1.4 How do you manage a 45-minute round?
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1.5 What questions should you ask first?
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1.6 What's the difference between functional and non-functional requirements?
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1.7 What's an API, and why define it before drawing boxes?
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1.8 How do you sketch the data model?
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1.9 What does a good high-level design look like?
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1.10 How do you choose what to deep dive into?
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1.11 How do you talk about trade-offs?
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1.12 What if you get stuck or don't know something?
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1.13 What are the most common mistakes?
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1.14 What does the bar look like: fresher vs SDE-2?
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Memory card and where the analogy breaks
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Practice: five levels
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Interview questions
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Solutions
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Sources
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Code lab
1. How to Approach a Design Question

Memory card and where the analogy breaks

3 min read+10 XP

The memory card (tear this page out)

#QuestionMemory code
1.1What is a design interview?No answer key, only reasons
1.2What's scored?The 5 Cs: Clarify, Create, Crack open, Compare, Communicate
1.3The framework?READ, then Draw, Dive, Defend
1.4Timing?5, 5, 10, 10, 10, 5
1.5What to ask first?Ask about SCALE before you scale: Scope, Count, Access pattern, Latency, Exactness
1.6Functional vs non-functional?Verbs vs adjectives (the adjectives pick the architecture)
1.7The API?Doors before rooms
1.8The data model?Store it the way you'll ask for it
1.9The high-level design?Draw it simple, walk it through
1.10The deep dive?Dive where it hurts
1.11Trade-offs?Because, Cost, Unless
1.12Stuck?Silence scores zero
1.13Mistakes?Don't build a skyscraper for a family of four
1.14The bar?Fresher: it works. SDE-2: it survives.

The whole chapter in one line: Ask before you draw, READ before you design, and give every big choice a because, a cost and an unless.

Where the analogy breaks

  • The interviewer is both the client and the judge. A real family only wants a good house. An interviewer also wants to see how you think, so they may hold back information on purpose to see if you ask.
  • An architect gets weeks. You get 45 minutes. That's why the timing split matters so much more for you.
  • A house is finished once it's built. Software never is. Traffic grows, features change and machines fail every day, which is why non-functional requirements like scalability and availability carry so much weight.

Quick check

Five questions on this chapter. Pick an answer, then check it.

quiz