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System design

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读扩散还是写扩散,以及那个有一千万粉丝的人。

Copy the prompt, then pick a model. It plays the interviewer and asks you through it scene by scene instead of handing you the answer.

On a phone with the app installed, the system opens the app directly. Links cannot open external apps inside WeChat — open it in a browser first.

The copied text ends with the answer key the model grades you against. Don't read it yourself first — working it out on your own is the point.

两种方案的名字谁都会说,值钱的是能算出写扩散的存储放大到什么量级,以及大 V 那个特例要不要单独开一条路。

面社交和内容方向的话,这道是起点。

★★★★☆ · about 45 min · Tests: 读扩散 vs 写扩散、大 V 问题、游标分页、存储放大

Cross-cutting patterns this one leans on

Hotspots and data skew Caching Message queues Replicas and replication lag Sharding and distributed IDs Capacity estimation

Have you done this one?

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Notes from people who did this one

Nobody has written yet. After you run it, say what came out of the conversation — which scene stumped you, which conclusion you changed afterwards.

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How to use this

How to start

  1. Pick a question, open it, copy the prompt.
  2. Paste it into a brand-new conversation — not one where you already discussed this question, or the model follows your old answers.
  3. Say nothing. Wait for its first question.

Four commands you can call out at any time

  • 跳过 move to the next scene now
  • 提示 give a direction, not the answer
  • 直说吧 spell this point out in full, then keep pressing on the trade-offs
  • 复盘 jump to the wrap-up and print the review card

Three traps

  • Don't do two questions in one conversation — context from the first makes the model prejudge your level.
  • Don't look up the answer the moment it asks. Being stuck for 30 seconds is itself useful information.
  • When it starts praising you, point it back to rule five — feeling validated crowds out noticing what you missed.

Suggested order: start with the cross-cutting drill as a parts test, use the short-link question to get used to the flow, then pick by the direction you interview for, and keep redoing the one about your own project.