How to find factorial recursively in Python

How to find factorial recursively in python

Factorial: For example, 5! refers to the "factorial of 5", that is, 5! = 1* 2*3*4*5.

"Recursion" is a function that calls itself.

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def f(x):
    if x == 0:
        return 0
    elif x == 1:
        return 1
    else:
        return (x * f(x-1))
print(f(5))

Code explanation: If x=5, then return the value of 5*f(4). If you want to know this value, you must first calculate what f(4) is equal to. According to the function f(x), f(4) = 4*f(3), so f(5) = 5*4*f(3). By analogy, f(5) = 5*4*3*2*f(1). Function f(x) says that when x==1, the return value is 1. So: f(5) = 5*4*3*2*1 = 120. Therefore, the output result is as follows:

120

It sounds very troublesome and hard to understand. What if we don’t use recursive functions? Using the most basic code, it can be written as:

f = 1
for i in range(1,6):
    f = f * i
print(f)

The result is still 120.

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