Week 12 · Day 6 · 2026-10-17 SAT · RETEST
Final synthesis and repair retest
Exact Daily Blocks
Retest the weakest repaired answer and synthesize the two unseen mocks into reusable Staff trade-offs.
| 08:50-10:55 | System design Run the weak-project reattempt, then compare Mock A and Mock B: operational truth, feedback loops, privacy boundaries, scope control, and Staff-level trade-offs. |
|---|---|
| 14:30-16:15 | NeetCode Backtracking Exactly three unique slots; each is 30m solve + 5m evidence. |
| 20:30-21:15 | Recall / mock repair Record final Chinese synthesis and English final recall; check PDF/audio artifacts. |
DDIA decision links
Only exact Ch13/Ch14 sections that change Week 12 decisions are linked.
| Decision question | Exact DDIA section | Design consequence |
|---|---|---|
| How do we repair a bad index, ranking, dashboard, or eval after code/schema evolution? | Ch13 - 应用演化后重新处理数据 | Keep raw events and provenance so derived state can be reprocessed after rubric, schema, or bug fixes. |
| When should reads become explicit feedback events? | Ch13 - 读也是事件 | Reads can improve ranking/evaluation only when consent, purpose, and anti-feedback-loop controls are present. |
Algorithm block
Diagnostic decision: select Backtracking, not a weakest prior tag, because no production scorecard records a weaker tag and final week needs recursive state-space pruning under pressure.
| Slot | Problem | Pattern | Invariant | Bug risk | Time | Space |
|---|---|---|---|---|---|---|
| 16 | Target Sum NEW · Backtracking · 30m solve + 5m evidence | sign assignment DFS/DP bridge | Each number receives exactly one sign. | Exponential DFS without noticing subset-sum conversion. | O(n sum) DP or O(2^n) | O(sum) DP |
| 17 | Sudoku Solver NEW · Backtracking · 30m solve + 5m evidence | constraint propagation DFS | Rows, columns, and boxes contain each digit once. | Not undoing constraints after failed digit. | O(9^empty) | O(empty) stack |
| 18 | Word Search II NEW · Backtracking · 30m solve + 5m evidence | trie-pruned grid DFS | DFS follows only prefixes that exist in the trie. | Not de-duplicating found words. | O(mn 4^L) | O(trie + L) |
Output
| Deliverable | Final synthesis artifact plus mock-to-map transfer notes. |
|---|---|
| Artifacts | 30-project map Chinese synthesis Synthesis audio English recall Recall PDF Weak repair Repair audio Cohort crosswalk |
Detailed lecture notes, audio, recall scripts, PDFs, Staff Q&A, and mock packs are archived locally and are intentionally not published on this site.