---
changelog:
  category: Release
  version: 20260902.205241.000000000
date: '2026-09-02T20:52:41Z'
seo:
  description: >-
    Finished Wed, Sep 2, 2026, 4:52 PM ET: all 3 core problems closed, 3
    problems closed that day. Scheduled: Wed Sep 2, 2026 · Phase: Phase II —
    Nodal & Grid ·…
title: Topic 10 — Matrix Index Math
type: changelog
---
<!-- release-topics: #12 -->
Finished Wed, Sep 2, 2026, 4:52 PM ET: all 3 core problems closed, 3 problems closed that day.

**Scheduled:** Wed Sep 2, 2026 · **Phase:** Phase II — Nodal & Grid · **Topic:** #12 · **Builds on:** Topic 3 — NOT graph traversal

## Closed Sep 2 — the day the topic finished

| Issue | Problem | Set | Difficulty | Closed (ET) | Solution |
| --- | --- | --- | --- | --- | --- |
| #91 | LC 48 · Rotate Image | core | medium | Sep 2 | [py](https://github.com/prdlk/leetcode/blob/20260902.205241.000000000/work/1/Medium/Array/48.rotate-image.py) · [docs](https://lc.prd.lk/48) |
| #92 | LC 54 · Spiral Matrix | core | medium | Sep 2 | [py](https://github.com/prdlk/leetcode/blob/20260902.205241.000000000/work/1/Medium/Array/54.spiral-matrix.py) · [docs](https://lc.prd.lk/54) |
| #93 | LC 73 · Set Matrix Zeroes | core | medium | Sep 2 | [py](https://github.com/prdlk/leetcode/blob/20260902.205241.000000000/work/1/Medium/Array/73.set-matrix-zeroes.py) · [docs](https://lc.prd.lk/73) |

## Open at release

| Issue | Problem | Set | Difficulty | Closed (ET) | Solution |
| --- | --- | --- | --- | --- | --- |
| #94 | LC 36 · Valid Sudoku | optional | medium | — | — |
| #95 | LC 289 · Game of Life | optional | medium | — | — |

---

`20260902.205241.000000000` is [timever](https://gist.github.com/twolfson/de1b004dd22536b8e668) for the UTC instant the core set completed; it tags 1e0e03d, the last main commit before it.