Topic 19 — Union-Find
Finished Wed, Sep 23, 2026, 3:40 PM ET: all 2 core problems closed, 2 problems closed that day.
Scheduled: Wed Sep 23, 2026 · Phase: Phase IV — Relational · Topic: #21 · Builds on: Topic 16’s problem class
Closed Sep 23 — the day the topic finished
| Issue | Problem | Set | Difficulty | Closed (ET) | Solution |
|---|---|---|---|---|---|
| #146 | LC 684 · Redundant Connection | core | medium | Sep 23 | py · docs |
| #147 | LC 323 · Number of Connected Components | core | medium | Sep 23 | py · docs |
Open at release
| Issue | Problem | Set | Difficulty | Closed (ET) | Solution |
|---|---|---|---|---|---|
| #148 | LC 721 · Accounts Merge | optional | medium | — | — |
| #217 | LC 547 · Number of Provinces | optional | medium | — | — |
| #220 | LC 1971 · Find if Path Exists in Graph | optional | easy | — | — |
20260923.194052.000000000 is timever for the UTC instant the core set completed; it tags ac4dc65, the last main commit before it.