Key-value stores enabling near-constant-time lookups through hashing.
Theory
Code
Theory & Description
A hash table (or hash map) stores key-value pairs using a hash function to compute an index into an array of buckets. The hash function converts keys into array indices, enabling near-constant-time lookups. Collision resolution strategies like chaining or open addressing handle cases where multiple keys map to the same index. Hash tables are among the most versatile and performant data structures.
Common Use Cases
- Database indexing and caching
- Implementing sets and dictionaries
- Counting frequencies and deduplication
- Symbol tables in compilers
Complexity Cheat Sheet
| Operation | Average | Worst |
|---|---|---|
| Access | O(1) | O(n) |
| Search | O(1) | O(n) |
| Insertion | O(1) | O(n) |
| Deletion | O(1) | O(n) |
| Space Complexity | O(n) | |
Visualization
Problems
Interactive Visualization
Interactive Visualization
An interactive playground for Hash Tables will appear here. Insert elements, step through operations, and watch the data structure update in real time.