Topic 06 — Stack
Finished Thu, Aug 27, 2026, 3:21 PM ET: all 3 core problems closed, 3 problems closed that day.
Scheduled: Thu Aug 27, 2026 · Phase: Phase I — Linear Structures · Topic: #8 · Builds on: independent primitive
Closed Aug 27 — the day the topic finished
| Issue | Problem | Set | Difficulty | Closed (ET) | Solution |
|---|---|---|---|---|---|
| #67 | LC 20 · Valid Parentheses | core | easy | Aug 27 | py · docs |
| #68 | LC 155 · Min Stack | core | medium | Aug 27 | py · docs |
| #69 | LC 150 · Evaluate Reverse Polish Notation | core | medium | Aug 27 | py · docs |
Open at release
| Issue | Problem | Set | Difficulty | Closed (ET) | Solution |
|---|---|---|---|---|---|
| #70 | LC 71 · Simplify Path | optional | medium | — | — |
| #71 | LC 224 · Basic Calculator | deferred | hard | — | — |
20260827.192131.000000000 is timever for the UTC instant the core set completed; it tags 9b5879b, the last main commit before it.