What is the time complexity of heaps law of permutations?

Question

Don't explain heap sort.

Answer 1

Jan Markus i couldn't get the last few lines

Answer 2

def generate(l,a):
if l ==1 :
print(*a)
else:
for i in range(l):
generate(l-1,a)
if i % 2==0:
a[i],a[l-1] = a[l-1],a[i]

else:
a[0],a[l-1] = a[l-1],a[0]

generate(3,[1,2,3])

Can you brak this down pls