输出数组的全排列

def swap(a, b):

    return b, a

 

def perminate(array, start, end):

    if start == end:

        print array

        return

 

    N = len(array)

 

    for i in range(start, N):

        array[i], array[start] = swap(array[i], array[start])

        perminate(array, start+1, end)

        array[i], array[start] = swap(array[i], array[start])

 

a = [1,2,3,4]

perminate(a, 0, len(a)-1)