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 读 Ad Click Aggregator 从 Understanding the Problem 到 High-Level Design；保留原文 Bad/Good/Great solution titles 并画 click -> stream -> OLAP path。 |
|---|---|
| 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 英语 recall：contrast batch pre-aggregation, stream processing, and raw lake reconciliation. |
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 |
|---|---|---|---|---|---|---|
| 7 | Add Two Numbers NEW · 30m solve + 5m evidence | digit carry | carry contains overflow from processed suffix | remaining carry after both lists end | O(n+m) | O(max(n,m)) |
| 8 | Find Duplicate Integer NEW · 30m solve + 5m evidence | cycle detection over values | array value is next pointer into index space | confusing index/value start | O(n) | O(1) |
| 9 | LRU Cache NEW · 30m solve + 5m evidence | hash map + doubly linked list | head/tail order mirrors recency | stale map pointer after eviction | O(1) | O(capacity) |
Hello Interview 精确目录
保留 live original titles；每行都有 canonical anchor 和 disposition。
| 项目 | 精确 canonical section | Disposition | 今天怎么用 |
|---|---|---|---|
| Ad Click Aggregator | Understanding the Problem | required reading | ad click collection and advertiser metrics |
| Ad Click Aggregator | Functional Requirements | required reading | redirect clicks and query one-minute metrics |
| Ad Click Aggregator | Non-Functional Requirements | required reading | 10k peak clicks/sec, low-latency analytics, no lost clicks, idempotency |
| Ad Click Aggregator | The Set Up | required reading | data-processing delivery framework |
| Ad Click Aggregator | Planning the Approach | required reading | interface first, then data flow |
| Ad Click Aggregator | System Interface | required reading | input click events and output advertiser metrics |
| Ad Click Aggregator | Data Flow | required reading | click, track/store, redirect, aggregate query |
| Ad Click Aggregator | High-Level Design | required reading | server-side redirect, stream, OLAP read model |
| Ad Click Aggregator | 1) Users can click on ads and be redirected to the target | required reading | compare client-side redirect with server-side redirect |
| Ad Click Aggregator | 2) Advertisers can query ad click metrics over time at 1 minute intervals | required reading | Bad/Good/Great: raw DB, batch OLAP, real-time stream processing |
| Ad Click Aggregator | Scaling Writes | pattern note | write-heavy path drives Kafka/Kinesis and Flink choices |
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 |
|---|---|---|
| Click stream needs durable low-latency ingestion | Ch12 · 传递事件流 | Kafka/Kinesis is a durable stream buffer, not the aggregate truth |
| One-minute click buckets must use event time | Ch12 · 事件时间与处理时间 | window by click/impression event time; expose processing lag separately |
| Metric windows need explicit bucket semantics | Ch12 · 窗口的类型 | tumbling one-minute buckets for advertiser reports; late corrections carry version/as-of |
本日项目 artifacts
今日产出、修复与英语 recall
| 必须交付 | Ad Click HLD：/click 302, signed impression payload, raw stream, Flink one-minute window, OLAP aggregate, advertiser query API。 |
|---|---|
| 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. |
Detailed lecture notes, audio, recall scripts, PDFs, Staff Q&A, and mock packs are archived locally and are intentionally not published on this site.