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Algorithm

Algorithm is a step-by-step procedure, which defines a set of instructions to be executed in a certain order to get the desired output. Algorithms are generally created independent of underlying languages, i.e. an algorithm can be implemented in more than one programming language.

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Characteristics of an Algorithm�

  • Unambiguous − Algorithm should be clear and unambiguous. Each of its steps (or phases), and their inputs/outputs should be clear and must lead to only one meaning.
  • Input − An algorithm should have 0 or more well-defined inputs.
  • Output − An algorithm should have 1 or more well-defined outputs, and should match the desired output.
  • Finiteness − Algorithms must terminate after a finite number of steps.
  • Feasibility − Should be feasible with the available resources.
  • Independent − An algorithm should have step-by-step directions, which should be independent of any programming code.

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Algorithm Complexity�

Suppose X is an algorithm, and n is the size of input data, the time and space used by the algorithm X are the two main factors, which decide the efficiency of X.

  • Time Factor − Time is measured by counting the number of key operations such as comparisons in the sorting algorithm.
  • Space Factor − Space is measured by counting the maximum memory space required by the algorithm.

The complexity of an algorithm f(n) gives the running time and/or the storage space required by the algorithm in terms of n as the size of input data.

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Analysis of Algorithm

Analysis of algorithm is the process of analyzing the problem-solving capability of the algorithm in terms of the time and size required (the size of memory for storage while implementation). However, the main concern of analysis of algorithms is the required time or performance. Generally, we perform the following types of analysis −

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  • Worst-case − The maximum number of steps taken on any instance of size n.
  • Best-case − The minimum number of steps taken on any instance of size n.
  • Average case − An average number of steps taken on any instance of size n.

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Amity School of Engineering & Technology