Hướng dẫn def factorial(n python)

View Discussion

Nội dung chính

• 1.Recursive approach: 
• 2. Iterative approach :
• 3. One line Solution (Using Ternary operator): 
• 4. By using In-built function : 
• Method: Using numpy.prod 
• Output 

Improve Article

Save Article

View Discussion

Improve Article

Save Article

Factorial of a non-negative integer, is multiplication of all integers smaller than or equal to n. For example factorial of 6 is 6*5*4*3*2*1 which is 720.

1.Recursive approach: 

python3

def factorial(n):

    return 1 if (n==1 or n==0) else n * factorial(n - 1);

num = 5;

print("Factorial of",num,"is",

factorial(num))

Output:

Factorial of 5 is 120

Time Complexity: O(n)
Auxiliary Space: O(n)

2. Iterative approach :

Method1:

python3

def factorial(n):

    if n < 0:

        return 0

    elif n == 0 or n == 1:

        return 1

    else:

        fact = 1

        while(n > 1):

            fact *= n

            n -= 1

        return fact

num = 5;

print("Factorial of",num,"is",

factorial(num))

Output:

Factorial of 5 is 120

Time Complexity: O(n)
Auxiliary Space: O(1)

Method2: 

Python3

def factorial(n):

    res = 1

    for i in range(2, n+1):

        res *= i

    return res

num = 5;

print("Factorial of", num, "is",

factorial(num))

Output

Factorial of 5 is 120

Time Complexity: O(n)
Auxiliary Space: O(1)

3. One line Solution (Using Ternary operator): 

Python3

def factorial(n):

    return 1 if (n==1 or n==0) else n * factorial(n - 1)

num = 5

print ("Factorial of",num,"is",

      factorial(num))

Output:

Factorial of 5 is 120

Time Complexity: O(n)
Auxiliary Space: O(n)

Please refer complete article on Program for factorial of a number for more details!

4. By using In-built function : 

In Python, math module contains a number of mathematical operations, which can be performed with ease using the module. math.factorial() function returns the factorial of desired number.

Syntax: math.factorial(x)

Parameter:
x: This is a numeric expression.

Returns:  factorial of desired number.

Python3

import math

def factorial(n):

    return(math.factorial(n))

num = 5

print("Factorial of", num, "is",

      factorial(num))

Output:

Factorial of 5 is 120

Method: Using numpy.prod 

Python3

import numpy

n=5

x=numpy.prod([i for i in range(1,n+1)])

print(x)

Output 

120

Time Complexity: O(n)
Auxiliary Space: O(1)