# Recursion

In computer science, recursion is a method of solving a problem where the solution depends on solutions to smaller instances of the same problem. For example, a factorial can be calculated recursively by multiplying a number by all the numbers below it. Recursion can be used to solve problems in many different areas, such as graphics or data structures.

#### What is recursion with example?

Recursion is a method of programming where a function calls itself in order to complete a task. For example, a factorial function could be written recursively like this:

def factorial(n):
if n == 1:
return 1
else:
return n * factorial(n-1)

In this example, the function calls itself until it reaches the base case of n = 1. At that point, it returns the result (1 * 2 * 3 * 4 * 5, in this case). What is a recursion in C? A recursion in C is a programming technique that allows a function to call itself repeatedly. This can be useful for solving certain types of problems, but it can also lead to infinite loops if the function is not written correctly.

### What is a recursion method?

A recursion method is a method that calls itself. A simple example of a recursion method is one that computes the factorial of a number. The factorial of a number is the product of all the integers from 1 up to that number. For example, the factorial of 5 is 5 * 4 * 3 * 2 * 1, or 120.

A recursion method can be used to compute the factorial of a number like this:

public static int factorial(int n) {
if (n <= 1) {
return 1;
} else {
return n * factorial(n-1);
}
}

In this example, the factorial() method calls itself, each time with a value that is one less than the previous value. When the value of n reaches 1, the method returns 1. The return value of each invocation of the method is then used in the next invocation, until the final value is returned.

#### Why is recursion used?

Recursion is a powerful tool for solving problems, but it can be difficult to understand and implement. When you break a problem down into smaller pieces, it can be easier to see how to solve it. Recursion allows you to take a complex problem and break it down into smaller, more manageable pieces.

Recursion is also a very efficient way to solve certain problems. By breaking a problem down into smaller pieces, you can often find a much more efficient solution than you would by trying to solve the problem as a whole.

Finally, recursion can be a very elegant solution to a problem. In many cases, a recursive solution is much simpler and cleaner than an equivalent non-recursive solution. Is recursion same as loop? No, recursion is not the same as a loop. A loop is a control flow statement that allows you to repeat a block of code a set number of times. A recursion is a function that calls itself.