WEEK 09 · 2026.09.21-09.27 · WRITER GATE

Day 3 - News Aggregator TRANSFER: blind attempt and HLD delta

2026-09-23 · WED · 先从 FB Post Search 迁移盲做，再用 Google News 原文修正 crawler、dedupe、canonical article 和 feed materialization。

中文深度讲义Staff Q&AGPT Live Mock证据验收

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。

08:50-09:2508:50-10:55 system design
Blind transfer attempt: reuse index/rank vocabulary, but list assumptions before reading.
09:25-10:0508:50-10:55 system design
Read News Aggregator headings through HLD and three functional paths.
10:05-10:3508:50-10:55 system design
Write exact delta: changed requirements, invalid assumptions, new bottleneck, follow-up.
10:35-10:5508:50-10:55 system design
DDIA Ch13: derived article/feed state, materialized cache and stale derived state.
14:30-16:15NeetCode Graphs
Three contiguous Graphs slots below; no other tag.
20:30-21:15Transfer script audio pass: explain crawl lag, dedupe lag and feed materialization lag separately.

算法模块

NeetCode Graphs, exactly three slots today, contiguous slots 7-9 of 21.

#Problem / modePatternInvariantBug riskTimeSpace
7Course Schedule
Graphs · NEW · 30m solve + 5m evidence		topological cycle detectiona course is finishable after all prerequisites leave visiting statenot distinguishing visiting vs visitedO(V+E)O(V+E)
8Course Schedule II
Graphs · NEW · 30m solve + 5m evidence		topological orderoutput order appends only nodes whose prerequisites are satisfiedreversing order in DFS incorrectlyO(V+E)O(V+E)
9Clone Graph Review
Graphs · NEW · 30m solve + 5m evidence		memoized traversal under time pressurethe memo map breaks cycles and preserves identityusing value as key when values may collideO(V+E)O(V)

今日产出

必须交付News transfer blind attempt plus complete link map first half.
修复规则If the answer treats news as user posts, add crawler/fetcher/parser/deduper/canonical cluster.

Hello Interview 精确目录

使用 live heading 的 original title 和 direct anchor。

项目Level精确 canonical sectionDispositionDay
News Aggregator / Google Newsh2Understanding the Problemblind attempt then readingDay 3
News Aggregator / Google Newsh3Functional Requirementsblind attempt then readingDay 3
News Aggregator / Google Newsh3Non-Functional Requirementsblind attempt then readingDay 3
News Aggregator / Google Newsh2The Set Upblind attempt then readingDay 3
News Aggregator / Google Newsh3Planning the Approachblind attempt then readingDay 3
News Aggregator / Google Newsh3Defining the Core Entitiesblind attempt then readingDay 3
News Aggregator / Google Newsh3API or System Interfaceblind attempt then readingDay 3
News Aggregator / Google Newsh2High-Level Designblind attempt then readingDay 3
News Aggregator / Google Newsh31) Users should be able to view an aggregated feed of news articles from thousands of source publishers all over the worldblind attempt then readingDay 3
News Aggregator / Google Newsh32) Users should be able to scroll through the feed "infinitely"blind attempt then readingDay 3
News Aggregator / Google Newsh33) Users should be able to click on articles and be redirected to the publisher's website to read the full contentblind attempt then readingDay 3

DDIA 精确决策卡

Only DDIA Ch4 and Ch13 decision links are allowed.

DayProjectDecisionLink
Day 3News Aggregatorfeed rows and index documents are derived from crawled source articleshttps://ddia.vonng.com/ch13/#id446
Day 3News Aggregatorhomepage/category feed caches are materialized views with staleness budgetshttps://ddia.vonng.com/ch13/#id451

Artifacts

PDF is intentionally absent; Week 9 requires MP3 only for the FULL/TRANSFER scripts.

News transfer script News transfer audio News transfer delta News link map
Local study materials
Detailed lecture notes, audio, recall scripts, PDFs, Staff Q&A, and mock packs are archived locally and are intentionally not published on this site.