WEEK 06 · 2026-09-06 · SUN

Week 6 synthesis：修复最弱回答，收敛 source/link/artifact/visual gate

只修 Week 6：把 ledger、aggregation、monitoring 三种 derived view 的共同不变量压成可复述答案。

今日固定时间表

只有三个学习窗口：08:50-10:55、14:30-16:15、20:30-21:15。section links 只放在本日页面。

08:50-10:55	System design 重做最低分 deep dive：换一个故障注入，必须讲 decision -> invariant -> failure -> recovery -> metric；检查 heading disposition 和 DDIA map。
14:30-16:15	NeetCode Linked List 三道连续题位，每题 30m solve + 5m pattern/invariant/bug/complexity evidence。
20:30-21:15	Recall / Staff Q&A / Mock 用 scorecard 做最终证据登记；不预读 Week 7，不修改 reviewer files。

算法模块

连续 NeetCode Linked List tag；每天恰好 3 个 slot。

#	Problem / mode	Pattern	Invariant	Bug risk	Time	Space
19	Remove Duplicates from Sorted List NEW · 30m solve + 5m evidence	single pass skip duplicates	current node is last unique value	skipping too far on tail	O(n)	O(1)
20	Delete Node in a Linked List NEW · 30m solve + 5m evidence	copy successor into node	target is not tail and can be overwritten	trying to update previous pointer	O(1)	O(1)
21	Middle of the Linked List NEW · 30m solve + 5m evidence	fast/slow	slow advances once per two fast steps	first vs second middle ambiguity	O(n)	O(1)

DDIA 精确决策卡

只读 Ch8、Ch12、Ch13 中能改变今天设计选择的小节。

项目问题	精确 DDIA subsection	改变的系统决定
Final synthesis must verify derived views	Ch13 · 数据流系统的正确性	low-latency views are trusted only when validated against durable source events
Repair loop must catch software bugs and bad promises	Ch13 · 信任但验证	use reconciliation, audits, and invariant metrics as the weekly proof

本日项目 artifacts

Payment System 中文讲稿 Payment System 中文音频 Payment System English recall Payment System PDF Ad Click Aggregator 中文讲稿 Ad Click Aggregator 中文音频 Ad Click Aggregator English recall Ad Click Aggregator PDF Metrics Monitoring 中文讲稿 Metrics Monitoring 中文音频 Metrics Monitoring English recall Metrics Monitoring PDF

今日产出、修复与英语 recall

必须交付	Week 6 scorecard ready：3 core contracts complete, 21 Linked List slots, links/media/PDF/visual smoke recorded。
修复规则	如果回答只说组件名，重写为 decision -> mechanism -> invariant -> failure window -> recovery -> metric。
English recall	Correctness is the durable source of truth; low-latency status, aggregates, dashboards, and alerts are views with freshness and repair semantics.

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.