Topic 18 — Topological Sort
Finished Tue, Sep 22, 2026, 3:02 PM ET: all 2 core problems closed, 2 problems closed that day.
Scheduled: Tue Sep 22, 2026 · Phase: Phase IV — Relational · Topic: #20 · Builds on: Topic 16
Closed Sep 22 — the day the topic finished
| Issue | Problem | Set | Difficulty | Closed (ET) | Solution |
|---|---|---|---|---|---|
| #142 | LC 207 · Course Schedule | core | medium | Sep 22 | py · docs |
| #143 | LC 210 · Course Schedule II | core | medium | Sep 22 | py · docs |
Open at release
| Issue | Problem | Set | Difficulty | Closed (ET) | Solution |
|---|---|---|---|---|---|
| #144 | LC 1462 · Course Schedule IV | optional | medium | — | — |
| #145 | LC 269 · Alien Dictionary | deferred | hard | — | — |
| #216 | LC 802 · Find Eventual Safe States | optional | medium | — | — |
20260922.190245.000000000 is timever for the UTC instant the core set completed; it tags 0009075, the last main commit before it.