---
changelog:
  category: Release
  version: 20260824.182006.000000000
date: '2026-08-24T18:20:06Z'
seo:
  description: >-
    Finished Mon, Aug 24, 2026, 2:20 PM ET: all 5 core problems closed, 5
    problems closed that day. Scheduled: Mon Aug 17, 2026 · Phase: Phase I —
    Linear…
title: Topic 01 — Hash-Based Lookup
type: changelog
---
<!-- release-topics: #3 -->
Finished Mon, Aug 24, 2026, 2:20 PM ET: all 5 core problems closed, 5 problems closed that day.

**Scheduled:** Mon Aug 17, 2026 · **Phase:** Phase I — Linear Structures · **Topic:** #3 · **Builds on:** nothing

## Closed Aug 24 — the day the topic finished

| Issue | Problem | Set | Difficulty | Closed (ET) | Solution |
| --- | --- | --- | --- | --- | --- |
| #27 | LC 217 · Contains Duplicate | core | easy | Aug 24 | [js](https://github.com/prdlk/leetcode/blob/20260824.182006.000000000/work/Easy/Array/217.contains-duplicate.js) · [docs](https://lc.prd.lk/217) |
| #28 | LC 242 · Valid Anagram | core | easy | Aug 24 | [js](https://github.com/prdlk/leetcode/blob/20260824.182006.000000000/work/Easy/Hash%20Table/242.valid-anagram.js) · [docs](https://lc.prd.lk/242) |
| #29 | LC 1 · Two Sum | core | easy | Aug 24 | — |
| #30 | LC 49 · Group Anagrams | core | medium | Aug 24 | [js](https://github.com/prdlk/leetcode/blob/20260824.182006.000000000/work/Medium/Array/49.group-anagrams.js) · [docs](https://lc.prd.lk/49) |
| #31 | LC 347 · Top K Frequent Elements | core | medium | Aug 24 | [js](https://github.com/prdlk/leetcode/blob/20260824.182006.000000000/work/Medium/Array/347.top-k-frequent-elements.js) · [docs](https://lc.prd.lk/347) |

## Open at release

| Issue | Problem | Set | Difficulty | Closed (ET) | Solution |
| --- | --- | --- | --- | --- | --- |
| #32 | LC 383 · Ransom Note | optional | easy | — | — |
| #33 | LC 205 · Isomorphic Strings | optional | easy | — | — |
| #34 | LC 128 · Longest Consecutive Sequence | optional | medium | — | — |
| #35 | LC 290 · Word Pattern | optional | easy | — | — |

---

`20260824.182006.000000000` is [timever](https://gist.github.com/twolfson/de1b004dd22536b8e668) for the UTC instant the core set completed; it tags 32a41bd, the last main commit before it.