This document discusses recursion in computer programming. It defines recursion as a technique that involves a procedure or function calling itself, either directly or indirectly. It notes that recursion requires a recursive case, where the code calls itself, and a base case, which stops recursion from continuing indefinitely. The document provides examples of using recursion to calculate factorials and the Fibonacci sequence in Python code. It also compares recursion to iteration, noting advantages like reducing time complexity, but disadvantages like using more memory.

1. RECURSION
With Python
Made by
Bima Sudarsono Adinsa 1906399083
Dennis Al Baihaqi Walangadi 1906400141
Muhammad Faisal Adi Soesatyo 1906293184
Muhammad Ivan Radman 1906399114
With assistance of Mr. Fariz Darari, S.Kom, M.Sc., Ph.D.

2. Recursion
What is recursion?
Recursion is a computer programming
technique involving the use of
procedure, subroutine, function, or
algorithm that calls itself either
directly or indirectly
https://xkcd.com/1516/

3. RecursionComponents
01
Recursive case
Part where the code calls it self
Base case
Base case is the condition that
stops recursion from continuing
on forever
Recursion consist of
02
!
Recursion without
Base case will result
Recursion Error
When a recursion doesn’t have
base case, it will run infinitely
and reached maximum depth

4. Example
How a particular problem is
solved using recursion?
The idea is to represent a problem in terms of one or more smaller problems,
and add one or more base conditions that stop the recursion.
For example, we can use recursion to solve factorials. Let’s solve 10!
10! means 10 x 9 x 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1
But 9! also means 9 x 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1
Thus, 10! Can be written as 10 x 9!
That means it can be translated to:
n! = n x (n-1)!
So on python we can write ...

5. Example
def factorial(num):
# Base case 0! = 1
if num == 0:
return 1
# Recursive case
else:
return num * factorial(num
- 1)
Example usage : Factorial in Python
Because 0! = 1, and factorial
doesn’t have negative value
Recursion case, when the
number is greater than 0,
multiply the number by the
number behind it

6. Example
Example usage : Fibonacci in Python
Fibonacci is a set of numbers that starts with a one or a zero, followed by a
one, and proceeds based on the rule that each number (called a Fibonacci
number) is equal to the sum of the preceding two numbers.
If the Fibonacci sequence is denoted F(n), where n is the first term in the
sequence, the following equation obtains for n = 0, where the first two terms are
defined as 0 and 1 by convention:
F (0) = 0, 1, 1, 2, 3, 5, 8, 13, 21, 34 ...
In some texts, it is customary to use n = 1. In that case, the first two terms are
defined as 1 and 1 by default, and therefore:
F (1) = 1, 1, 2, 3, 5, 8, 13, 21, 34 …
So, in python we can write ...

7. Example
Example usage : Fibonacci in Python
def fib(n):
# Base case n = 0 or n = 1
if n == 0 or n == 1:
return n
# Recursive case
else:
return fib(n - 1) + fib(n
- 2)
Because based on the
theory, fibonacci sequence
starts from 0 or 1
if we want to get the value of
n, we have to sum the value of
n-1 with value of n-2
This algorithm will return a fibonacci number on index n

8. RecvsIter
Recursion vs Iteration
● Advantages
○ It can reduce time complexity
○ It adds clarity and reduce your
time to write and debug the code
○ It is better in problem based on
tree traversals / structures
● Disadvantages
○ It uses more memory for the stack
○ It can be slow, due to the overhead
of maintaining stack

9. CREDITS: This presentation template was created
by Slidesgo, including icons by Flaticon, and
infographics & images by Freepik.
References
● https://www.geeksforgeeks.org/recursion/
● https://www.cs.utah.edu/~germain/PPS/Topics/recursion.html
● https://www.khanacademy.org/computing/computer-
science/algorithms/recursive-algorithms/a/recursion
● Punch, William F. ,Richard Enbody, Practice of Computing Using Python,
3rd Edition (2017)
● https://medium.com/@williambdale/recursion-the-pros-and-cons-76d32d75973a
● https://stackoverflow.com/questions/5250733/what-are-the-advantages-and-
disadvantages-of-recursion
● https://desain.cs.ui.ac.id/static/img/asset/logo.zip