Week 12 · Day 2 · 2026-10-13 TUE · REPAIR
Weakest core replay: ChatGPT
Exact Daily Blocks
Replay the selected weakest Core project and repair missing or weakest answer dimensions.
| 08:50-10:55 | System design Run a 45-minute ChatGPT replay: scope, model serving, retrieval/context budget, streaming, tenant isolation, evals, fallbacks. Inject one privacy leak and one eval-regression counterexample. |
|---|---|
| 14:30-16:15 | NeetCode Backtracking Exactly three unique slots; each is 30m solve + 5m evidence. |
| 20:30-21:15 | Recall / mock repair Record the repair using invariant, failure trigger, recovery, metric, and replacement-score rule. |
DDIA decision links
Only exact Ch13/Ch14 sections that change Week 12 decisions are linked.
| Decision question | Exact DDIA section | Design consequence |
|---|---|---|
| How should the weakest core replay prove correctness rather than confidence? | Ch13 - 及时性与完整性 | The repair must state what can be stale, what must be complete, and which invariant metric proves the boundary. |
| How do we avoid believing a repaired answer just because it sounds polished? | Ch13 - 信任但验证 | The repair protocol requires audit evidence, counterexample injection, and a replacement score rule. |
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 |
|---|---|---|---|---|---|---|
| 4 | Combination Sum II NEW · Backtracking · 30m solve + 5m evidence | single-use DFS with duplicate skip | Each candidate index is used at most once. | Duplicate skip before sorting. | O(2^n) | O(n) stack |
| 5 | Combinations NEW · Backtracking · 30m solve + 5m evidence | choose k from range | Path length plus remaining count must be enough to reach k. | No pruning on remaining candidates. | O(C(n,k) k) | O(k) stack + output |
| 6 | Permutations NEW · Backtracking · 30m solve + 5m evidence | used-set DFS | A value appears once in the current permutation. | Mutating used/path without backtracking both. | O(n n!) | O(n) stack + output |
Output
| Deliverable | Weak-project repair sheet plus final replacement answer. |
|---|---|
| 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.