Programmiererforum

A=[1,2,3]
c=[]
def perm(a):
global c
if len(a)==1:
p=a
else:
for i in a:
p=[i]+perm(a.remove(i))
c+=[p]
return p
perm(A)
print(c)

TypeError: object of type 'NoneType' has no len()

Ich versuche Code zu schreiben, um Permutationen auszugeben. Wie repariere ich es?
Danke! < /P>
[code]A=[1,2,3]
c=[]
def perm(a):
global c
if len(a)==1:
p=a
else:
for i in a:
p=[i]+perm(a.remove(i))
c+=[p]
return p
perm(A)
print(c)

TypeError: object of type 'NoneType' has no len()
[/code]