Introduction to Algorithm

An algorithm is a sequence of unambiguous instructions for solving a
computational problem, i.e., for obtaining a required output for any
legitimate input in a finite amount of time.

More precisely, an algorithm is a method or process to solve a problem satisfying the following properties:

• Finiteness: Terminates after a finite number of steps.
• Definiteness: Each step must be rigorously and unambiguously specified.
• Input: Valid inputs must be clearly specified.
• Output: can be proved to produce the correct output given a valid input.
• Effectiveness: Steps must be sufficiently simple and basic.