Algorithm is a very common word in computer science, especially in case of any procedural programming languages. In this chapter we will know about algorithms, different types of algorithms, different approaches to designing an algorithm, analysis of algorithms, etc. We will also be able to learn how an algorithm can be written using different control structures.
2.1 What Is an Algorithm?
We can define an algorithm as a step-by-step procedure to solve a problem. This is much like a recipe for cooking an item. To cook a new item, we follow the instructions one by one as given in its recipe. Similarly, to write a program we need to follow the algorithm. Once we are able to generate the algorithm of a problem, then writing its code is not a huge task at all. But before writing an algorithm we have to keep in mind that any algorithm must have the following characteristics:
• Input: Inputs are the values that are supplied externally. Inputs are those without which we cannot proceed with the problems. Every algorithm must have zero or any number of inputs.
• Output: Output is the outcome of an algorithm. Every algorithm produces at least one output.
• Definiteness: All the instructions in the algorithm must be clear and should not be ambiguous.
• Finiteness: Whatever may be the inputs for all possible values, every algorithm must terminate after executing a finite number of steps.
• Effectiveness: All the instructions in the algorithm should be very basic so that every instruction of the algorithm can be converted to programming instruction easily. Effectiveness indicates that every instruction is a step towards the solution.
• Feasible: Every instruction must be a feasible instruction.
2.2 Importance of an Algorithm
When we try to write a program, first we need to identify all the tasks. Some tasks are easily identifiable while some tasks maybe hidden within the problem definition. For that a detailed analysis of the problem is required. After proper analysis we are able to find what the expected output is. What are the inputs required using which we can get the output? Using the inputs how we reach the solution? To accomplish this ‘how’, after identifying all the tasks we need to arrange them in a proper sequence.
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