A function calls itself. But why? Basically, Recursion provides a concise and elegant way to solve complex problems. How? By breaking, them down into smaller, more manageable subproblems.

Why do we need Recursion?

Problem-Solving: Recursion is especially effective when dealing with problems that can be naturally divided into smaller instances of the same problem. By solving these smaller instances recursively, you can arrive at a solution for the larger problem.

Simplification: Recursion simplifies complex problems by breaking them down into smaller more easily solvable subproblems. Each recursive call focuses on a subset of the problem, making it easier to reason about and solve.

Code Readability: Recursive solutions often provide a more intuitive and readable representation of the problem compared to their iterative counterparts. The recursive structure closely mirrors the problem’s inherent recursive nature, making the code easier to read and maintain.

Efficiency: In certain scenarios, recursive algorithms can be more efficient than their iterative counterparts. For example, recursive algorithms can be more efficient when dealing with tree-like data structures or problems that have overlapping sub-problems. However, this depends upon specific problems and their implementation, and in some cases, recursion can be less efficient due to the overhead of function calls and stack space usage.

Mathematical Modelling: Recursion is often used in Mathematical modeling and computation, as many mathematical concepts naturally lend themselves to recursive formulations. Problems such as Fibonacci numbers, factorials, and fractal generation are frequently solved using Recursion.

Data Structure: Many fundamental data structures, such as linked lists, trees, and graphs can be effectively implemented and manipulated using Recursive techniques. Recursion simplifies the traversal and manipulation of these data structures, allowing for concise and expressive code.

Example of generating a Factorial using Recursion(Java):

public class FactorialExample {

public static void main(String[] args) {
int number = 5;
int result = factorial(number);
System. out.println(“Factorial of “ + number + “ is “ + result);
}

public static int factorial(int n) {
// Base case: factorial of 0 is 1
if (n == 0) {
return 1;
}
// Recursive case: calculate factorial using recursion
else {
return n * factorial(n — 1);
}
}
}

In the code above, there is something called the Base Case. The base case is required to be put into a recursive program. Otherwise, in the event of carrying out a recursive call without a base case, the calling becomes infinite and there will be no stopping. Hence, the program runs out of memory creating a stack overflow.