Question

算法：输入要返回的字母数，输入循环a-z，锁定第一个字符，循环第二个字符，锁定前两个，依此类推等等。输出看起来像a，b，c，d ...... aa，ab，ac，ad ... aaa，aab，aac ......等等。我是python的新手。我有一些东西在字母表中循环，但我的问题是锁定第一个并循环第二个，依此类推。

w = 'abcdefghijklmnopqrstuvwxyz'
n = input ("# of characters: ")

for a in range(0,n):
        for i in w:
                print i

Answer 1

alphabet = 'abcdefghijklmnopqrstuvwxyz'
l= ['']
for i in range(input):
    l = [letter + item for letter in alphabet for item in l]
    for item in l:
        print(item)

我认为这就是你正在寻找的东西

Answer 2

为避免巨大的RAM要求，请使用itertools.combinations一次生成一个输出，为您处理“锁定”：

from future_builtins import map  # Not needed on Py3, only on Py2
from itertools import combinations

w = 'abcdefghijklmnopqrstuvwxyz'
# Don't use input on Py2; it's an implicit eval, which is terrible
# raw_input gets str, and you can explicitly convert to int
n = int(raw_input("# of characters: "))

# You want 1-n inclusive on both ends, not 0-n exclusive at the end, so tweak range
for wdlen in xrange(1, n+1):
    # Generator based map with ''.join efficiently converts the tuples
    # from combinations to str as you iterate
    for wd in map(''.join, combinations(w, wdlen)):
        print wd

python 2.7字生成器

2 个答案: