DDIA Ch13
数据库的端到端原则
Question: 为什么 exactly-once 要说成端到端效果而不是 broker 魔法？
链路每端都要 operation id、dedupe、reconcile；单个中间件承诺不够。
第 7 周 - 第 6 天 - 2026-09-12 SAT - MOCK - adaptive
Adaptive mock: YouTube CORE plus Top K pressure round
今日目标
一场 45 分钟 YouTube adaptive mock with two deep dives, followed by 25-35 minute Top K attempt and one Strava transfer follow-up.
| 08:50-09:00 | Set target 选择今天 YouTube mock 的 two deep dives: upload/transcode or publish/CDN or TopK/view-count tangent. |
|---|---|
| 09:00-09:45 | YouTube adaptive mock 45 分钟完整 core mock；interviewer 根据你的 choices 追问 two deep dives. |
| 09:45-10:20 | Top K attempt 25-35 分钟 Top K exact design attempt, then one late-event follow-up. |
| 10:20-10:45 | Strava transfer follow-up 解释 offline replay and stale friend feed; 写一条 repair note. |
| 10:45-10:55 | Spoken close 只讲最弱答案的 corrected version。 |
| 14:30-16:15 | NeetCode Trees Exactly three contiguous Trees slots. Each slot is 30m solve + 5m pattern/invariant/bug/complexity evidence. |
| 20:30-21:15 | Recall / Q&A / repair 20:30-21:15 根据 scorecard 选 weakest answer，重答 8 分钟，替换分数。 |
Exact source links
Use original Hello Interview titles and current canonical anchors. Inline Bad/Good/Great headings without standalone live anchors link to their parent canonical section.
| Original title / direct link | Disposition | Use |
|---|---|---|
| Week 7 Live Mock | mock | adaptive prompt and scoring contract |
| Staff Q&A | Q&A | realistic Senior+/Staff follow-ups |
DDIA decision cards
Only exact Ch11/Ch12/Ch13 sections that change today's design are assigned.
DDIA Ch13
抑制重复
Question: 如何把重复请求压成一次操作？
client request id、upload chunk fingerprint、activity sample id、view event id 都是重复抑制键。
算法模块
Contiguous live NeetCode Trees order. No reviews. Three slots per day.
| # | Problem / mode | Pattern | Invariant | Bug risk | Time | Space |
|---|---|---|---|---|---|---|
| 16 | Evaluate Boolean Binary Tree NEW - 30m solve + 5m evidence | 表达式树后序 | 内部节点由左右布尔结果组合。 | 叶子 0/1 和 operator 2/3 混淆。 | O(n) | O(h) |
| 17 | Closest Binary Search Tree Value NEW - 30m solve + 5m evidence | BST 单路径搜索 | 当前 best 始终是已访问节点里最接近 target 的值。 | tie-breaking 不明确；浮点差值比较。 | O(h) | O(1) |
| 18 | Binary Tree Vertical Order Traversal NEW - 30m solve + 5m evidence | BFS + column index | 同列按 BFS 层序保留从上到下、从左到右。 | DFS 破坏同层顺序。 | O(n log c) | O(n) |
今日验收
| Output | Mock transcript, five-dimension score, two deep-dive notes, weakest-answer repair. |
|---|---|
| Hard fail | Passive reading without a spoken answer; missing invariant/failure/recovery/metric; any day outside Week 7 touched. |
| Repair | Pick the weakest answer and redo it for 8 minutes with one new failure window. |
Detailed lecture notes, audio, recall scripts, PDFs, Staff Q&A, and mock packs are archived locally and are intentionally not published on this site.