Topic 13 — Binary Search Tree
Finished Sat, Sep 5, 2026, 4:33 PM ET: all 3 core problems closed, 3 problems closed that day.
Scheduled: Mon Sep 7, 2026 · Phase: Phase III — Hierarchical · Topic: #15 · Builds on: Topics 5 + 11
Closed Sep 5 — the day the topic finished
| Issue | Problem | Set | Difficulty | Closed (ET) | Solution |
|---|---|---|---|---|---|
| #111 | LC 98 · Validate BST | core | medium | Sep 5 | py · docs |
| #112 | LC 230 · Kth Smallest in BST | core | medium | Sep 5 | py · docs |
| #113 | LC 235 · LCA of BST | core | medium | Sep 5 | py · docs |
Open at release
| Issue | Problem | Set | Difficulty | Closed (ET) | Solution |
|---|---|---|---|---|---|
| #114 | LC 105 · Build from Preorder + Inorder | optional | medium | — | — |
| #115 | LC 530 · Minimum Absolute Difference | optional | easy | — | — |
| #116 | LC 173 · BST Iterator | optional | medium | — | — |
| #117 | LC 108 · Sorted Array to BST | optional | easy | — | — |
20260905.203314.000000000 is timever for the UTC instant the core set completed; it tags 6c18301, the last main commit before it.