Data Structures & Algorithms

In the branch of computer science, a data structure is a particular way of storing and organizing data in a computer so that it can be used efficiently.

The different systems of data structures are suited to different kinds of applications, and some are highly specialized to specific tasks. For example, the B-trees are particularly well-suited for implementation of databases, while compiler implementations usually use hash tables to look up identifiers.

A data structure is used in almost every program or software system. Some of these Specific data structures are essential ingredients of many efficient algorithms, and make possible the management of huge amounts of data, such as large databases and internet indexing services.

Basic principles

Data structures is generally based on the ability of a computer to fetch and store data at any place in its memory, specified by an address — a bit string that can be itself stored in memory and manipulated by the program. Thus the array data structures and the records are based on computing the addresses of data items with arithmetic operations; while the linked data structures are based on storing addresses of data items within the structure itself. Many types of data structures use both principles, sometimes combined in non-trivial ways (as in XOR linking).

Algorithm

In mathematics or in computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. An algorithm is used for calculation, data processing, and automated reasoning.

Starting from the initial state and initial input (perhaps null), the instructions describe a computation that, when executed, will proceed through a finite number of well-defined successive states, eventually producing “output” and terminating at a final ending state. The transition of one state to the next is not necessarily deterministic; some algorithms, known as randomized algorithms, incorporate random input.