Kacam.net

System design

短链系统

最简单的一道,专门考基本功。

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.

拿它当入门:题目简单,正好用来熟悉这套流程和那四个口令,别一上来就啃支付。

但简单不等于好答 —— 它考的是有没有基本功,而信息量全在那几个数字里,估算含糊的话后面答得再漂亮也是背的。这份提示词特意要求每个环节都往下追两层,追到答不上来为止,那是正常结局。

★★☆☆☆ · about 30 min · Tests: 发号、KV 存储、缓存命中、301 vs 302、容量估算

Cross-cutting patterns this one leans on

Capacity estimation Sharding and distributed IDs Caching Message queues Security

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.