Permutation in Python

Basics of the post

1. The permutation means changing a linear order set into a new order set. Simply said, it means rearranging the elements of a set in an organized way.

2. The basic formula of permutation is given below. 'n' represents the total number of elements and 'r' represent the number of selected elements in a set.

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Step to solve permutation

1. First of all, we will take two input values for 'n' and 'r'

n=int(input())
r=int(input())

2. we will find the factorial of a number using the recursion process. This works will be done in a function name factorial.

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

3. Then, the formula of permutation will be implemented and it is blocked in a function name permutation.

def permutaion(n, r):
    return factorial(n) / factorial(n-r)

4. After that, we will call the permutation function which receives 'n' and 'r' parameters.

result = int(permutaion(n,r))
print(result)

Now the final code will be like below,