| 0705 | Design HashSet LeetCode XXXX Design, Array, Hash Table, Linked List, Hash Function | Easy | | |
| 0706 | Design HashMap LeetCode XXXX Design, Array, Hash Table, Linked List, Hash Function | Easy | | |
| 0217 | Contains Duplicate LeetCode XXXX Array, Hash Table, Sorting | Easy | | |
| 0219 | Contains Duplicate II LeetCode XXXX Array, Hash Table, Sliding Window | Easy | | |
| 0220 | Contains Duplicate III LeetCode 0220 Array, Bucket Sort, Ordered Set, Sorting, Sliding Window | Hard | | |
| 1941 | Check if All Characters Have Equal Number of Occurrences LeetCode XXXX Hash Table, String, Counting | Easy | | |
| 0136 | Single Number LeetCode XXXX Bit Manipulation, Array | Easy | | |
| 0383 | Ransom Note LeetCode XXXX Hash Table, String, Counting | Easy | | |
| 0349 | Intersection of Two Arrays LeetCode XXXX Array, Hash Table, Two Pointers, Binary Search, Sorting | Easy | | |
| 0350 | Intersection of Two Arrays II LeetCode XXXX Array, Hash Table, Two Pointers, Binary Search, Sorting | Easy | | |
| 0036 | Valid Sudoku LeetCode XXXX Array, Hash Table, Matrix | Medium | | |
| 0001 | Two Sum LeetCode XXXX Array, Hash Table | Easy | | |
| 0015 | 3Sum LeetCode XXXX Array, Two Pointers, Sorting | Medium | | |
| 0018 | 4Sum LeetCode XXXX Array, Two Pointers, Sorting | Medium | | |
| 0454 | 4Sum II LeetCode XXXX Array, Hash Table | Medium | | |
| 0041 | First Missing Positive LeetCode 0041 Array, Hash Table | Hard | | |
| 0128 | Longest Consecutive Sequence LeetCode XXXX Union Find, Array, Hash Table | Medium | | |
| 0202 | Happy Number LeetCode XXXX Hash Table, Mathematics, Two Pointers | Easy | | |
| 0242 | Valid Anagram LeetCode XXXX Hash Table, String, Sorting | Easy | | |
| 0205 | Isomorphic Strings LeetCode XXXX Hash Table, String | Easy | | |
| 0442 | Find All Duplicates in an Array | | Array, Hash Table | Medium |
| 0268 | Missing Number LeetCode XXXX Bit Manipulation, Array, Hash Table, Mathematics, Binary Search, Sorting | Easy | | |
| 0451 | Sort Characters By Frequency LeetCode XXXX Hash Table, String, Bucket Sort, Counting, Sorting, Heap (Priority Queue) | Medium | | |
| 0049 | Group Anagrams LeetCode XXXX Array, Hash Table, String, Sorting | Medium | | |
| 0599 | Minimum Index Sum of Two Lists LeetCode XXXX Array, Hash Table, String | Easy | | |
| 0387 | First Unique Character in a String LeetCode XXXX Queue, Hash Table, String, Counting | Easy | | |
| 0447 | Number of Boomerangs LeetCode XXXX Array, Hash Table, Mathematics | Medium | | |
| 0149 | Max Points on a Line LeetCode 0149 Geometry, Array, Hash Table, Mathematics | Hard | | |
| 0359 | Logger Rate Limiter LeetCode XXXX Design, Hash Table | Easy | | |
| 0811 | Subdomain Visit Count LeetCode XXXX Array, Hash Table, String, Counting | Medium | | |