---
changelog:
  category: Release
  version: 20260901.182216.000000000
date: '2026-09-01T18:22:16Z'
seo:
  description: >-
    Finished Tue, Sep 1, 2026, 2:22 PM ET: all 2 core problems closed, 2
    problems closed that day. Scheduled: Tue Sep 1, 2026 · Phase: Phase II —
    Nodal & Grid ·…
title: Topic 09 — Hybrid Structures
type: changelog
---
<!-- release-topics: #11 -->
Finished Tue, Sep 1, 2026, 2:22 PM ET: all 2 core problems closed, 2 problems closed that day.

**Scheduled:** Tue Sep 1, 2026 · **Phase:** Phase II — Nodal & Grid · **Topic:** #11 · **Builds on:** Topics 1 + 8

## Closed Sep 1 — the day the topic finished

| Issue | Problem | Set | Difficulty | Closed (ET) | Solution |
| --- | --- | --- | --- | --- | --- |
| #87 | LC 146 · LRU Cache | core | medium | Sep 1 | [py](https://github.com/prdlk/leetcode/blob/20260901.182216.000000000/work/1/Medium/Hash%20Table/146.lru-cache.py) · [docs](https://lc.prd.lk/146) |
| #88 | LC 2 · Add Two Numbers | core | medium | Sep 1 | [py](https://github.com/prdlk/leetcode/blob/20260901.182216.000000000/work/1/Medium/Linked%20List/2.add-two-numbers.py) · [docs](https://lc.prd.lk/2) |

## Open at release

| Issue | Problem | Set | Difficulty | Closed (ET) | Solution |
| --- | --- | --- | --- | --- | --- |
| #89 | LC 138 · Copy List with Random Pointer | optional | medium | — | — |
| #90 | LC 380 · Insert Delete GetRandom O(1) | optional | medium | — | — |

---

`20260901.182216.000000000` is [timever](https://gist.github.com/twolfson/de1b004dd22536b8e668) for the UTC instant the core set completed; it tags cc29304, the last main commit before it.