An algorithm is defined as a finite set of steps that guarantees an optimal solution to a problem in a finite amount of time. An example algorithm for finding the average of two numbers in the C programming language is given, with 4 steps. The key characteristics of algorithms are that they have an input, produce an output, terminate in a finite number of steps, have definite unambiguous steps, and provide enough information at each step to produce results. Performance of algorithms is measured by time complexity and space complexity, with time complexity usually being more important. Good algorithms should run in less time and use less memory.

1. Algorithm
Dr. Kuppusamy .P
Associate Professor / SCOPE

2. Algorithm
A finite set of statements that guarantees an optimal solution for logical and
mathematical problems in finite interval of time.
Example Problem : Average of 2 numbers
Algorithm Source Code in ‘C’
1. Declare Variables int a,b, add;
2. Get input scanf(“%d %d” &a, &b);
3. Find average and assign the value average= (a+b)/2;
4. Display output result printf(“%d”,average);
No. of Statements = 4
Optimal Solution = average of 2 numbers
Dr. Kuppusamy P

3. Characteristics of Algorithm
• Input: Zero or more quantities which are externally
supplied.
• Output: At least one quantity is generated.
• Finiteness: Execution terminates after a finite number of
steps for all possible inputs.
• Definiteness: Each step must be clear and unambiguous.
• Effectiveness: Every step must be given enough
information to produce results.
Dr. Kuppusamy P

4. Measure the performance of Algorithms
• Time Complexity
• Space Complexity
- Computational resources (time complexity) is
usually more important than space complexity
Good Algorithms Should:
▪ Run in less time i.e. Less Time Complexity
▪ Consume less memory i.e. Less Space
Complexity
Dr. Kuppusamy P

5. References
Dr. Kuppusamy P
• Thomas H. Cormen, Charles E. Leiserson, Ronald L. Rivest, Clifford Stein,
“Introduction to Algorithms”, MIT Press.