Enumerating Gene Orders

In this problem we are given the task to find all the possible permutations of a list from 1 to n, where n ≤ 7. We are given n and are supposed to return the total number of permutations and a list of all the different permutations. To clarify, if we are told that n = 3, then the total number of permutations is 3! which is equal to 6 and we should print the following:

6      

1 2 3

1 3 2

2 1 3

2 3 1

3 1 2

3 2 1

It was fairly easy to make this program since Python3 has a built in library for factorials and another built in library for making permutations. The following is the final code:

import math                                         

import itertools                                    

n = 3                                               

print(math.factorial(n))                            

perm = itertools.permutations(list(range(1, n + 1)))

for i, j in enumerate(list(perm)):                  

    permutation = ''                                

    for item in j:                                  

        permutation += str(item) + ' '              

    print(permutation)