Datastructure

A data structure is a way of organizing data in memory to enable efficient access and modification. It defines how data is stored and how operations are performed, often corresponding to an abstract data type that specifies behavior while hiding implementation details.

Common data structures include arrays, linked lists, stacks, queues, trees, graphs, and hash tables. Arrays store elements contiguously for fast index-based access but can be costly to resize. Linked lists use nodes connected by pointers, enabling easy insertions and deletions but slower access. Hash tables offer fast average lookups, while trees and graphs model hierarchical or relational structures.

Operations such as insert, delete, search, and traverse have different performance profiles. Time and space costs are described by Big-O notation and depend on the structure and its usage. For example, array access is O(1) but insertions in the middle are O(n); balanced trees provide O(log n) operations; hash tables are typically O(1) on average but can degrade with collisions.

Design considerations include memory usage, cache locality, mutation frequency, and expected data size. Some structures are static, others dynamic with resizing. The choice of structure influences software performance and correctness.

Data structures are central to algorithms and systems, from databases and file systems to compilers and simulations.