What is Recursion?

Recursion is defined as a process which calls itself directly or indirectly and the corresponding function is called a recursive function.

Properties of Recursion:

Recursion has some important properties. Some of which are mentioned below:

• The primary property of recursion is the ability to solve a problem by breaking it down into smaller sub-problems, each of which can be solved in the same way.
• A recursive function must have a base case or stopping criteria to avoid infinite recursion.
• Recursion involves calling the same function within itself, which leads to a call stack.
• Recursive functions may be less efficient than iterative solutions in terms of memory and performance.

Types of Recursion:

1. Direct recursion: When a function is called within itself directly it is called direct recursion. This can be further categorised into four types: 
   • Tail recursion,  
   • Head recursion,  
   • Tree recursion and 
   • Nested recursion.
2. Indirect recursion: Indirect recursion occurs when a function calls another function that eventually calls the original function and it forms a cycle.

To learn more about types of recursion, refer to this article.

Applications of Recursion:

Recursion is used in many fields of computer science and mathematics, which includes:

• Searching and sorting algorithms: Recursive algorithms are used to search and sort data structures like trees and graphs.
• Mathematical calculations: Recursive algorithms are used to solve problems such as factorial, Fibonacci sequence, etc.
• Compiler design: Recursion is used in the design of compilers to parse and analyze programming languages.
• Graphics: many computer graphics algorithms, such as fractals and the Mandelbrot set, use recursion to generate complex patterns.
• Artificial intelligence: recursive neural networks are used in natural language processing, computer vision, and other AI applications.

Advantages of Recursion:

• Recursion can simplify complex problems by breaking them down into smaller, more manageable pieces.
• Recursive code can be more readable and easier to understand than iterative code.
• Recursion is essential for some algorithms and data structures.
• Also with recursion, we can reduce the length of code and become more readable and understandable to the user/ programmer.

Disadvantages of Recursion:

• Recursion can be less efficient than iterative solutions in terms of memory and performance.
• Recursive functions can be more challenging to debug and understand than iterative solutions.
• Recursion can lead to stack overflow errors if the recursion depth is too high.

What else can you read?

• Introduction to Recursion – Data Structure and Algorithm Tutorials
• Types of Recursion
• Recursive Functions