Algorithm in Data Structure: Characteristics, Steps and Examples
Learn Algorithm in Data Structure in very simple language. This chapter explains algorithm definition, characteristics, properties, steps to design an algorithm, examples, pseudocode, dry run, real-life applications and important exam questions.
What is an Algorithm in Data Structure?
An algorithm in Data Structure is a finite sequence of clear and ordered steps used to solve a problem or perform an operation. It takes some input, processes it through well-defined steps and produces the required output.
Many students think an algorithm means writing programming code. Because of this, they get confused before even starting the topic. An algorithm is actually much simpler. It is only a step-by-step solution to a problem. Programming code is written later to implement those steps on a computer.
This chapter provides a complete algorithm in Data Structure for beginners. It covers algorithm definition, characteristics of algorithm, properties of algorithm, steps of algorithm, algorithm examples, algorithm with pseudocode and importance of algorithm in Data Structure.
Introduction to Algorithm in Data Structure
Whenever we solve a problem, we normally follow some steps. A computer also needs a clear sequence of steps before it can solve a problem.
This sequence is called an algorithm.
For example, suppose we want to find the largest number from a list. First we need a method for comparing the numbers. That method becomes the algorithm. After that, we can implement the algorithm using C, Java, Python or another programming language.
Algorithm Definition
An algorithm is a finite set of clear, unambiguous and ordered instructions used to solve a particular problem and produce the required output from given input.
Algorithm in Data Structure with Example
Data Structures store data, while algorithms tell us what operations should be performed on that data.
Array
10, 20, 30, 40
Compare each value
with required value
Value Found
or Not Found
How Does an Algorithm Work?
The basic working of an algorithm is easy to understand.
Input
The algorithm receives the required values or data.
Processing
The algorithm performs its defined operations step by step.
Output
After processing, the algorithm produces the final result.
Real-Life Example of an Algorithm
Before looking at programming examples, think about making a cup of tea.
Take a pan and required ingredients.
Heat the required amount of water.
Add tea, sugar and milk.
Allow the mixture to boil properly.
Filter the tea and serve it.
These are ordered steps for reaching a result. In the same way, a computer algorithm gives ordered steps for solving a computational problem.
Characteristics of a Good Algorithm
A proper algorithm should satisfy some important conditions. These are commonly called the characteristics of algorithm or properties of algorithm.
Input
An algorithm may accept zero or more input values required to solve the problem.
Output
It should produce at least one meaningful result.
Definiteness
Every step must be clear and unambiguous.
Finiteness
The algorithm must finish after a finite number of steps.
Effectiveness
Every step should be simple enough to be performed practically.
Generality
A good algorithm should solve a class of similar problems, not only one specific input.
Input → Output → Definiteness → Finiteness → Effectiveness → Generality
Characteristics of Algorithm with Examples
| Characteristic | Meaning | Simple Example |
|---|---|---|
| Input | Values provided to algorithm | Two numbers A and B |
| Output | Result produced by algorithm | Sum of A and B |
| Definiteness | Every step must be clear | Add A and B |
| Finiteness | Algorithm must stop | Ends after printing result |
| Effectiveness | Steps must be practically executable | Compare two numbers |
| Generality | Works for different valid inputs | Add any two valid numbers |
Steps to Develop an Algorithm
Students often ask, “How do I write an algorithm for a problem?” You can follow these basic steps.
First understand exactly what has to be solved.
Decide what values the algorithm will receive.
Decide what result must be produced.
Write the sequence of operations required to reach the answer.
Write each instruction in simple and unambiguous language.
Try the steps using sample input and verify the result.
Check whether the solution can be made simpler or more efficient.
How to Write an Algorithm?
There is no single programming-language syntax for writing an algorithm. The main aim is to make the steps clear.
A simple format is:
Algorithm: Name of Algorithm Step 1: Start Step 2: Read input Step 3: Perform required operation Step 4: Display result Step 5: Stop
Algorithm to Find Sum of Two Numbers
This is one of the easiest algorithm examples for beginners.
Algorithm: Sum of Two Numbers Step 1: Start Step 2: Read A and B Step 3: SUM = A + B Step 4: Display SUM Step 5: Stop
Pictorial Representation
Dry Run
Suppose A = 10 and B = 20.
Algorithm to Find the Largest of Two Numbers
Algorithm: Largest of Two Numbers
Step 1: Start
Step 2: Read A and B
Step 3: If A > B
Display A as largest
Else
Display B as largest
Step 4: Stop
Visual Logic
A = 25 and B = 18
Since 25 > 18, the output is 25 is the largest number.
Algorithm to Check Even or Odd Number
Algorithm: Check Even or Odd
Step 1: Start
Step 2: Read N
Step 3: If N % 2 == 0
Display "Even"
Else
Display "Odd"
Step 4: Stop
If N = 14, then 14 % 2 gives 0, so the number is Even.
Algorithm Example in Data Structure: Linear Search
Let us now connect an algorithm with an actual Data Structure.
Suppose an Array contains:
We want to search for 40.
Algorithm: Linear Search
Step 1: Start
Step 2: Read array and target value
Step 3: Start from first element
Step 4: Compare each element with target
Step 5: If target is found
Display its position
Else continue searching
Step 6: If all elements are checked
Display "Not Found"
Step 7: Stop
Dry Run for Target = 40
| Step | Element Checked | Comparison | Result |
|---|---|---|---|
| 1 | 10 | 10 == 40? | No |
| 2 | 20 | 20 == 40? | No |
| 3 | 30 | 30 == 40? | No |
| 4 | 40 | 40 == 40? | Found |
Algorithm and Pseudocode
Pseudocode is a simple way of writing the logic of a program using programming-like statements without following the strict syntax of a real programming language.
Algorithm
Written as clear step-by-step instructions.
Step 1: Read A, B Step 2: C = A + B Step 3: Display C
Pseudocode
Written in a programming-like form.
INPUT A, B C ← A + B PRINT C
Difference Between Algorithm and Program
| Basis | Algorithm | Program |
|---|---|---|
| Meaning | Step-by-step solution | Implementation of solution in a programming language |
| Language | Language independent | Written in C, Java, Python, etc. |
| Syntax | No strict programming syntax | Must follow language syntax |
| Execution | Cannot directly run on computer | Can be compiled/interpreted and executed |
| Main Purpose | Plan the solution | Perform the solution on a computer |
Algorithm vs Flowchart
| Point | Algorithm | Flowchart |
|---|---|---|
| Representation | Text-based steps | Graphical representation |
| Use | Explains procedure | Shows visual flow |
| Creation | Usually faster to write | Requires flowchart symbols |
| Modification | Easy to modify | May require redrawing |
Common Types of Algorithms in Data Structure
Algorithms can be classified according to the kind of problem they solve. You will study many of these in detail in later chapters.
Searching Algorithm
Used to find a required element.
Sorting Algorithm
Used to arrange elements in a particular order.
Recursive Algorithm
Solves a problem by calling itself on a smaller problem.
Tree Algorithm
Used for traversal, searching and operations on trees.
Graph Algorithm
Used for traversal, shortest path and connectivity.
Optimization Algorithm
Tries to find a better or best solution under given conditions.
Efficiency of an Algorithm
Two algorithms may solve the same problem but may not perform equally well. One may take less time, while another may require less memory.
This is called algorithm efficiency.
Time Efficiency
It tells us how the amount of work grows as the input size increases.
Space Efficiency
It tells us how much additional memory an algorithm needs.
Importance of Algorithm in Data Structure
Algorithms and Data Structures work together. A Data Structure organizes the data, while an algorithm decides how that data will be processed.
Find required data.
Arrange data properly.
Add new data.
Remove existing data.
Visit tree nodes.
Explore connected nodes.
Find efficient routes.
Improve solution efficiency.
Advantages of Algorithm
Easy to Understand
Complex problems can be divided into simple steps.
Language Independent
The same algorithm can be implemented in different programming languages.
Easy Debugging
Logic mistakes can often be identified before coding.
Better Planning
It gives a clear plan before program implementation.
Easy Modification
Steps can be changed without rewriting an entire program.
Supports Analysis
Algorithms can be compared on correctness, time and memory requirements.
Limitations of Algorithm
- Writing detailed steps for a very large problem can become lengthy.
- An algorithm itself cannot be directly executed by a computer.
- Complex logic may still be difficult to represent using only text.
- Algorithms do not automatically guarantee the most efficient solution.
- They still need to be implemented and tested using a programming language.
Common Mistakes Students Make
Wrong. An algorithm is a logical solution; a program is its implementation in a programming language.
No. Algorithms are language independent and do not require strict C syntax.
No. It must first be implemented as a program.
No. Every step should be definite and clearly understandable.
A proper algorithm must terminate after a finite number of steps.
No. A correct solution may still use unnecessary time or memory.
Important Exam Questions on Algorithm in Data Structure
These questions cover the major areas commonly asked from Algorithm in Data Structure.
1. Define Algorithm.
2. What is Finiteness in an Algorithm?
3. What is Definiteness?
4. What is the Output of an Algorithm?
5. What is Pseudocode?
6. What is Algorithm Efficiency?
7. Explain the Characteristics of a Good Algorithm.
A good algorithm should have the following characteristics:
- Input: It accepts zero or more input values.
- Output: It produces at least one result.
- Definiteness: Every step should be clear.
- Finiteness: It must terminate after finite steps.
- Effectiveness: Every operation should be practical.
- Generality: It should work for valid inputs of the problem class.
8. Explain the Steps for Developing an Algorithm.
The main steps are:
- Understand the problem.
- Identify required input.
- Identify expected output.
- Design the logic.
- Write the instructions clearly.
- Test using sample data.
- Analyse and improve the solution if needed.
9. Write an Algorithm to Find the Sum of Two Numbers.
Step 1: Start
Step 2: Read A and B
Step 3: SUM = A + B
Step 4: Display SUM
Step 5: Stop
10. Differentiate Between Algorithm and Program.
An algorithm is a step-by-step logical solution to a problem, while a program is the implementation of that solution using a programming language.
Algorithms are language independent and do not require strict syntax. Programs follow the syntax of a language such as C or Java.
An algorithm cannot directly execute on a computer, while a program can be compiled or interpreted and executed.
11. What is an Algorithm? Explain its Characteristics with Suitable Examples.
An algorithm is a finite sequence of well-defined steps used to solve a problem. It accepts input, performs a series of operations and produces the required output.
The important characteristics of a good algorithm are input, output, definiteness, finiteness, effectiveness and generality.
Input represents the values given to the algorithm. Output is the result produced by it. Definiteness means every instruction should be clear and unambiguous.
Finiteness means the algorithm must terminate after a finite number of steps. Effectiveness means each operation should be simple and executable. Generality means the algorithm should work for different valid inputs of the same problem.
For example, an algorithm to add two numbers can accept any two valid numbers as input, add them, display the result and then terminate.
Algorithms are important in Data Structure because operations such as searching, sorting, insertion, deletion and traversal are all performed through algorithms.
12. Explain Algorithm Development Steps and Write an Algorithm to Find the Largest of Two Numbers.
Algorithm development starts by understanding the problem. After that, the input and expected output are identified. The logical steps are then designed and written clearly. The algorithm is tested with sample values and improved if necessary.
Algorithm to Find Largest of Two Numbers:
Step 1: Start
Step 2: Read A and B
Step 3: If A > B, display A as the largest.
Step 4: Otherwise, display B as the largest.
Step 5: Stop
13. Explain the Importance of Algorithms in Data Structure.
Data Structures are used to organize and store data, but the stored data becomes useful only when operations are performed on it. Algorithms define how those operations are carried out.
Searching algorithms are used to find data. Sorting algorithms arrange elements. Insertion and deletion algorithms add or remove values.
Tree and graph algorithms are used for traversal, searching and path finding. Algorithms are also compared according to execution time and memory requirements.
Therefore, algorithms and Data Structures work together to create efficient computer programs.
Algorithm in Data Structure MCQs
- A programming language
- A sequence of steps to solve a problem
- A computer device
- A database only
- Input
- Output
- Finiteness
- Generality
- Ambiguous
- Unclear
- Definite
- Infinite
- Output
- Input
- Finiteness
- Effectiveness
- Language dependent
- Language independent
- Only written in C
- Only written in Java
- Program
- Paper only
- Database only
- Flow line only
- Finiteness
- Definiteness
- Ambiguity
- Effectiveness
- Searching Algorithm
- Database
- Data Type
- Compiler
- A hardware language
- An informal programming-like description of logic
- A database command only
- A compiler
- Time and memory use
- Screen size
- Keyboard speed
- File name
Important Viva Questions
| Viva Question | Short Answer |
|---|---|
| What is an algorithm? | A finite step-by-step method for solving a problem. |
| Is an algorithm language dependent? | No. |
| What is definiteness? | Every step must be clear and unambiguous. |
| What is finiteness? | The algorithm must terminate after finite steps. |
| What is effectiveness? | Every operation should be practical and executable. |
| What is input? | Data supplied to the algorithm. |
| What is output? | The result produced by the algorithm. |
| What is pseudocode? | A programming-like description of an algorithm. |
| What is a program? | An implementation of an algorithm in a programming language. |
| What is algorithm efficiency? | How effectively an algorithm uses time and memory. |
| Name one searching algorithm. | Linear Search. |
| Name one sorting algorithm. | Bubble Sort. |
Quick Revision
Step-by-step method to solve a problem.
Data supplied to algorithm.
Result produced by algorithm.
Steps must be clear.
Algorithm must terminate.
Steps must be practical.
Works for different valid inputs.
Programming-like description of logic.
Implementation of algorithm.
Related to time and memory use.
Frequently Asked Questions
What is Algorithm in Data Structure?
An algorithm in Data Structure is a finite sequence of clear steps used to perform operations such as searching, sorting, insertion, deletion and traversal on stored data.
What are the Characteristics of an Algorithm?
Important characteristics include input, output, definiteness, finiteness, effectiveness and generality.
What are the Steps of an Algorithm?
Understand the problem, identify input and output, design the logic, write clear steps, test the algorithm and improve it if necessary.
What is an Algorithm with Example?
An algorithm is a step-by-step procedure. For example, to add two numbers: read A and B, calculate A + B, display the result and stop.
What is the Difference Between Algorithm and Program?
An algorithm describes the logical steps to solve a problem, while a program implements those steps using a programming language.
What is the Difference Between Algorithm and Flowchart?
An algorithm represents a solution using written steps, while a flowchart represents the same logic graphically using symbols and arrows.
What is Pseudocode?
Pseudocode is an informal way of describing program logic using programming-like statements without strict programming syntax.
Why are Algorithms Important in Data Structure?
Algorithms define how operations such as searching, sorting, insertion, deletion and traversal are performed on Data Structures.
What Makes an Algorithm Good?
A good algorithm should be correct, clear, finite, effective and suitable for the required input.
What is Algorithm Efficiency?
Algorithm efficiency describes how the resource requirements of an algorithm, especially time and additional memory, grow as the input size increases.
Conclusion
Algorithm becomes much easier when you understand that it is simply a clear plan for solving a problem. You do not need to start with programming syntax. First understand the problem, decide the input and output, and then write the solution in simple ordered steps.
In this chapter, we covered algorithm in Data Structure, algorithm definition, characteristics of algorithm, properties of algorithm, steps of algorithm, steps to develop an algorithm, algorithm examples, algorithm with pseudocode, algorithm vs program, algorithm vs flowchart, types of algorithms in Data Structure, algorithm efficiency and the importance of algorithm in Data Structure.
This foundation is very important because upcoming topics such as searching, sorting, recursion, trees and graphs all depend on algorithms. Once you are comfortable with writing simple algorithms, the later Data Structure chapters become much easier to understand.
