WEEK 09 · 2026.09.21-09.27 · WRITER GATE
Day 6 - Yelp TRANSFER: reviews, abuse, geo pagination and mock
2026-09-26 · SAT · 补齐 Yelp deep dives：average rating, one review per business, complex search, named locations, final design and Staff expectations。
今日固定时间表
三个学习窗口必须保持 exactly 08:50-10:55, 14:30-16:15, 20:30-21:15。
| 08:50-09:20 | 08:50-10:55 system design Blind reattempt: new review appears on detail page while search/ranking remains moderation-aware. |
|---|---|
| 09:20-10:05 | 08:50-10:55 system design Read all remaining Yelp deep dives, final design and level expectations. |
| 10:05-10:35 | 08:50-10:55 system design Live mock pressure: geo boundaries, stable pagination, rating aggregates, abuse signals and business move. |
| 10:35-10:55 | 08:50-10:55 system design DDIA Ch13 verification: compare source tables, aggregates and search index after backfill. |
| 14:30-16:15 | NeetCode Graphs Three contiguous Graphs slots below; no other tag. |
| 20:30-21:15 | Staff Q&A nodes 12-16, then 20-minute Yelp transfer mock. |
算法模块
NeetCode Graphs, exactly three slots today, contiguous slots 16-18 of 21.
| # | Problem / mode | Pattern | Invariant | Bug risk | Time | Space |
|---|---|---|---|---|---|---|
| 16 | Redundant Connection Graphs · NEW · 30m solve + 5m evidence | union-find cycle edge | first edge joining same root is redundant | unioning before checking same root | O(E alpha V) | O(V) |
| 17 | Accounts Merge Graphs · NEW · 30m solve + 5m evidence | union-find by email | all emails connected through an account share a root owner | losing sorted email output | O(N alpha N + E log E) | O(E) |
| 18 | Pacific Atlantic Review Graphs · NEW · 30m solve + 5m evidence | reverse reachability review | height condition reverses to neighbor height >= current | using strict > and losing equal-height paths | O(mn) | O(mn) |
今日产出
| 必须交付 | Yelp transfer final mapping plus live mock setup. |
|---|---|
| 修复规则 | If rating is updated synchronously without moderation, add pending/approved review states and aggregate replay. |
Hello Interview 精确目录
使用 live heading 的 original title 和 direct anchor。
| 项目 | Level | 精确 canonical section | Disposition | Day |
|---|---|---|---|---|
| Yelp | h2 | Potential Deep Dives | transfer deep dive | Day 6 |
| Yelp | h3 | 1) How would you efficiently calculate and update the average rating for businesses to ensure it's readily available in search results? | transfer deep dive | Day 6 |
| Yelp | h3 | 2) How would you modify your system to ensure that a user can only leave one review per business | transfer deep dive | Day 6 |
| Yelp | h3 | 3) How can you improve search to handle complex queries more efficiently | transfer deep dive | Day 6 |
| Yelp | h3 | 4) How would you modify your system to allow searching by predefined location names, such as cities or neighborhoods? | transfer deep dive | Day 6 |
| Yelp | h2 | Final Design | transfer deep dive | Day 6 |
| Yelp | h2 | What is Expected at Each Level? | level expectation | Day 6 |
| Yelp | h3 | Mid-level | level expectation | Day 6 |
| Yelp | h3 | Senior | level expectation | Day 6 |
| Yelp | h3 | Staff+ | level expectation | Day 6 |
DDIA 精确决策卡
Only DDIA Ch4 and Ch13 decision links are allowed.
| Day | Project | Decision | Link |
|---|---|---|---|
| Day 6 | Yelp | text plus geo search combines full text retrieval with precise second-pass filters | https://ddia.vonng.com/ch4/#sec_storage_full_text |
| Day 6 | Yelp | review/rating aggregate and search index are derived state that needs verification | https://ddia.vonng.com/ch13/#sec_future_verification |
Artifacts
PDF is intentionally absent; Week 9 requires MP3 only for the FULL/TRANSFER scripts.
Detailed lecture notes, audio, recall scripts, PDFs, Staff Q&A, and mock packs are archived locally and are intentionally not published on this site.