DSA
DSA/HashMap & HashSet
HashMap & HashSet
Coming soonUse hash-based structures to deduplicate, group, and look up in O(1), and learn the patterns that make them the right tool.
12
Planned lessons
11
Coding problems
6h
Est. study time
Easy
Difficulty
Overview
Hash-based structures give constant-time membership, counting, and grouping. This course shows how to trade space for time and when a hash map is the right tool.
Why it matters
A hash map is often the difference between O(n²) and O(n). Knowing when it's worth the extra space — and when a sort is cleaner — is a core interview judgement call.
What the course will cover
- Frequency counting and anagram grouping
- Set membership for de-duplication and cycles
- Hashing composite keys and coordinates
- Collision behaviour and load factor at a high level
- Patterns: Group Anagrams, Longest Consecutive Sequence
Interview relevance
Hashing shows up everywhere as the optimisation step. Interviewers expect you to reach for it naturally and articulate the space cost you're accepting.
Topics you'll master
HashMapHashSetGrouping
In the meantime, dive into a published track to keep your momentum.