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Programming Concepts Intermediate

What is Hash Table?

A data structure that maps keys to values using a hash function, providing average O(1) time complexity for lookups, insertions, and deletions.

Hash tables compute a hash of the key to determine where to store the value in an array. Collisions (different keys mapping to same index) are handled by chaining (linked lists) or open addressing (probing nearby slots).

Hash tables power dictionaries (Python dict), objects (JavaScript), HashMaps (Java), and associative arrays (PHP). They are the most commonly used data structure for fast key-based lookups. Performance degrades with many collisions or high load factors.

Related Terms

Algorithm
A step-by-step procedure for solving a problem or performing a computation, defined as a finite sequence of instructions.
Dependency Injection
A design pattern where objects receive their dependencies from external sources rather than creating them internally.
Recursion
A programming technique where a function calls itself to solve a problem by breaking it into smaller subproblems.
Singleton Pattern
A design pattern that restricts a class to a single instance and provides a global point of access to that instance.
Linked List
A linear data structure where elements are stored in nodes, each containing data and a pointer to the next node in the sequence.
Immutable Object
An object whose state cannot be modified after creation, providing thread safety and predictable behavior in concurrent systems.
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