Frequency Counting / Hash Map Lookup Problems
572 Frequency Counting / Hash Map Lookup problems on LeetCode, a Arrays & Hashing interview pattern, ranked by importance (how often it comes up in real interviews). Difficulty (ELO) and importance shown per problem.
| # | PROBLEM | DIFF | ELO | IMP | PATTERNS |
|---|---|---|---|---|---|
| 1 | Longest Consecutive Sequence | Medium | 1412 | 91 | Union-Find |
| 2 | Group Anagrams | Easy | 1219 | 90 | Sorting + Comparison |
| 3 | Contains Duplicate | Easy | 978 | 82 | |
| 4 | Valid Anagram | Easy | 1025 | 82 | Sorting + Comparison |
| 5 | Majority Element | Easy | 1052 | 82 |
MORE ARRAYS & HASHING PATTERNS
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