In case you can’t use Python’s itertools or in case you want a simple, recursive python implementation for a permutation of a list:
[python]
def perm(a,k=0):
if(k==len(a)):
print a
else:
for i in xrange(k,len(a)):
a[k],a[i] = a[i],a[k]
perm(a, k+1)
a[k],a[i] = a[i],a[k]
perm([1,2,3])
[/python]
Output:
[1, 2, 3] [1, 3, 2] [2, 1, 3] [2, 3, 1] [3, 2, 1] [3, 1, 2]
This Python implementation is based in the algorithm presented in the book Computer Algorithms by Horowitz, Sahni and Rajasekaran.