List Permutations

permutation.py

import copy

final = []

def main(Arr, res):
    if not Arr:
        final.append(res)
        return


    for elem in Arr:
        A = copy.deepcopy(Arr)
        if res is None:
            local_res = [elem]
        else:
            local_res = copy.deepcopy(res)
            local_res.append(elem)

        A.remove(elem)

        main(A, local_res)



if __name__ == '__main__':
    main([1, 2, 3, 4], None)
    print final
    print len(final)

Run with python 2.7

-- python permutation.py