Week 12 · Day 7 · 2026-10-18 SUN · GATE
Final gate and READY_FOR_REVIEW
Exact Daily Blocks
Complete Week 12 only, record evidence, and stop at READY_FOR_REVIEW.
| 08:50-10:55 | System design Run the scorecard: 30/30 map rows, two mock contracts, weak repair, exact DDIA links, Backtracking 21 slots, media/PDF, local/external anchors, 1440/390 smoke. |
|---|---|
| 14:30-16:15 | NeetCode Backtracking Exactly three unique slots; each is 30m solve + 5m evidence. |
| 20:30-21:15 | Recall / mock repair Final 45-minute recall: ten random mechanism rows, one mock deep dive, one privacy/accountability answer. |
DDIA decision links
Only exact Ch13/Ch14 sections that change Week 12 decisions are linked.
| Decision question | Exact DDIA section | Design consequence |
|---|---|---|
| Which Week 12 decisions require policy beyond engineering taste? | Ch14 - 立法与自律 | The final answer names policy, accountability, privacy, and audit choices when systems affect people. |
Final gate also reuses every Week 12 DDIA decision from the scorecard.
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 |
|---|---|---|---|---|---|---|
| 19 | Unique Paths III NEW · Backtracking · 30m solve + 5m evidence | visit-all DFS | A valid path visits every non-obstacle square exactly once. | Stopping at end before all squares are visited. | O(4^empty) | O(empty) stack |
| 20 | Partition to K Equal Sum Subsets NEW · Backtracking · 30m solve + 5m evidence | bucket DFS with pruning | Every bucket target sum is equal and each item is used once. | Symmetric empty-bucket repeats. | O(k 2^n) | O(n) used |
| 21 | Matchsticks to Square NEW · Backtracking · 30m solve + 5m evidence | four bucket DFS | Each side sum equals total/4. | Trying equal side states repeatedly. | O(4^n) | O(n) stack |
Output
| Deliverable | Week 12 production record with READY_FOR_REVIEW. |
|---|---|
| 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.