用Python以字典序產生n個數的排列

 1 #!/usr/bin/python
 2 #coding:utf-8
 3 def next_permutation(A):
 4         '''
 5         input:  array of a permutation of n numbers
 6         output: the next permutation
 7         Algorithm: dicttionary order 
 8         '''
 9         #print(A)
10         n = len(A)
11         last = n - 1
12         i = last
13         while i>0 and A[i]<A[i-1]:
14                 i -= 1
15         if i==0:
16                 return False
17         k = i
18         j = last
19         while j >= i:
20                 if A[j]>A[i-1] and A[j]<A[k]:
21                         k = j
22                 j -= 1
23         A[k],A[i-1] = A[i-1],A[k]
24         A[i:] = A[i:][::-1]
25         return True
26 
27 def permutation(n):
28         '''
29         Input:  int num n
30         Output: permutation of the n number from small to big
31         '''
32         B = []
33         A = list(range(1,n+1))
34         B.append(A[::])
35         flag = next_permutation(A)
36         B.append(A[::])
37         while flag:
38                 flag = next_permutation(A)
39                 B.append(A[::])     
40                                     
41         return B      
42 
43 AA = permutation(4)
44 for i in AA:
45         print(i)