BEGINNER · 4 PRACTICE PROBLEMS
Arrays & Hashing
Find the pattern. Make every lookup count.
THE CORE IDEA
Hash map lookup
Trade a little space for fast lookups. Great for counting, grouping, and finding pairs.
O(n)A good place to practice
Start simple, then build up to the next challenge.
| Solved | Problem | Difficulty | Topic | Acceptance | Bookmark |
|---|---|---|---|---|---|
| Two Sum | Easy | Arrays & Hashing | 55.2% | ||
| Contains Duplicate | Easy | Arrays & Hashing | 62.5% | ||
| Valid Anagram | Easy | Arrays & Hashing | 66.2% | ||
| Group Anagrams | Medium | Arrays & Hashing | 70.4% |