Set 03 - Hash Maps Deep Dive
Use Practice Loop if you need a reset.
Problems
| Problem | Difficulty | Pattern | Video |
|---|---|---|---|
| LC 242. Valid Anagram | Easy | Hash Map Count | Video |
| LC 49. Group Anagrams | Medium | Hash Map + Sort | Video |
| LC 347. Top K Frequent Elements | Medium | Hash Map + Heap | Video |
| LC 271. Encode and Decode Strings | Medium | Delimiter | Video |
Deliverables
- Write a 1-line invariant for each problem.
- Note 1 edge case or pitfall per problem.
- Record time-to-first-correct solution.
Notes
- LC 242: count frequencies; compare counts (or sort strings).
- LC 49: group by key (sorted string or count vector).
- LC 347: freq map + bucket or heap for top-k.
- LC 271: encode with length prefix to avoid delimiter collisions.
Review
- Time spent + where you got stuck?
- Biggest mistake or missed edge case?
- One concrete improvement for next time.
Comments
Share your approach or ask questions
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