An algorithm is a sequence of steps for one particular method of solving a problem, similar to the instructions of a recipe when cooking. The word is derived from the name of al-Khwarizmi, a mathematician active in Baghdad in the 9th century CE.
An algorithm consists of the steps to follow in solving a problem. When encoded in computer programs, algorithms operate on data values, preferably data maintained in a consistent data structure. Thus an algorithm is the recipe, while the data structure is the well-stored ingredients on which the recipe is designed to operate.
Nicklaus Wirth, the inventor of the programming language Pascal, titled one of his books "Algorithms + Data Structures = Programs" (ISBN 0130224189) to indicate the complementary nature of algorithms and data structures, and their centrality to computing.
Algorithms are usually expressed independently of the programming language, typically in terms of a brief, informal list of commands called pseudocode, or diagrammatically in the form of a flowchart.
Examples of different categories of algorithms used in computer programming include:
- Bounding limit
- Fourier transform
- Text string
Basic algorithm designs
There are several general methods for designing algorithms. Some of the most common are
- Divide and conquer strategies. These typically yield algorithms of complexity, or better.
- The greedy method.
- Dynamic programming.