我想你可以将其分类为拼字游戏风格的问题,但是由于朋友提到英国电视测验节目倒数计时,它开始了.演出中的各种表演包括参赛者被提出了一组乱码的信件,他们必须提出最长的话.我的朋友提到的是“RAEPKWAEN”.
在相当短的时间内,我用Python鞭打了一些东西来处理这个问题,使用PyEnchant来处理字典查找,但是我注意到它真的不能扩展这些.
这是我目前所在的
#!/usr/bin/python
from itertools import permutations
import enchant
from sys import argv
def find_longest(origin):
s = enchant.Dict("en_US")
for i in range(len(origin),-1):
print "Checking against words of length %d" % i
pool = permutations(origin,i)
for comb in pool:
word = ''.join(comb)
if s.check(word):
return word
return ""
if (__name__)== '__main__':
result = find_longest(argv[1])
print result
就像他们在节目中使用的9个字母的例子,9个阶乘= 362,880和8个阶乘= 40,320就好了.在这个规模上,即使它必须检查所有可能的排列和字长度,这不是很多.
然而,一旦你达到了14个字符,这是87,178,291,200个可能的组合,这意味着你依赖运气,迅速找到一个14个字符的字.
用上面的例子,我的机器大约需要12 1/2秒才能找到“reawaken”.使用14个字符的加密字,我们可以在23天的时间内谈话,只是为了检查所有可能的14个字符的排列.
有没有更有效的方法来处理这个？
解决方法
实施
Jeroen Coupé想法
his answer与字母数：
from collections import defaultdict,Counter
def find_longest(origin,known_words):
return iter_longest(origin,known_words).next()
def iter_longest(origin,known_words,min_length=1):
origin_map = Counter(origin)
for i in xrange(len(origin) + 1,min_length - 1,-1):
for word in known_words[i]:
if check_same_letters(origin_map,word):
yield word
def check_same_letters(origin_map,word):
new_map = Counter(word)
return all(new_map[let] <= origin_map[let] for let in word)
def load_words_from(file_path):
known_words = defaultdict(list)
with open(file_path) as f:
for line in f:
word = line.strip()
known_words[len(word)].append(word)
return known_words
if __name__ == '__main__':
known_words = load_words_from('words_list.txt')
origin = 'raepkwaen'
big_origin = 'raepkwaenaqwertyuiopasdfghjklzxcvbnmqwertyuiopasdfghjklzxcvbnmqwertyuiopasdfghjklzxcvbnmqwertyuiopasdfghjklzxcvbnm'
print find_longest(big_origin,known_words)
print list(iter_longest(origin,5))
输出(对于我的小58000字dict)：
counterrevolutionaries ['reawaken','awaken','enwrap','weaken','weaker','apnea','arena','awake','aware','newer','paean','parka','pekan','prank','prawn','preen','renew','waken','wreak']
笔记：
>这是简单的实现,没有优化.
> words_list.txt – 可以在Linux上使用/usr/share / dict / words.
UPDATE
如果我们只需要找到一次词,并且我们有字典,按长度排序的单词,例如通过这个脚本：
with open('words_list.txt') as f:
words = f.readlines()
with open('words_by_len.txt','w') as f:
for word in sorted(words,key=lambda w: len(w),reverse=True):
f.write(word)
我们可以找到最长的字,而不是加载完整的dict到内存：
from collections import Counter
import sys
def check_same_letters(origin_map,word):
new_map = Counter(word)
return all(new_map[let] <= origin_map[let] for let in word)
def iter_longest_from_file(origin,file_path,min_length=1):
origin_map = Counter(origin)
origin_len = len(origin)
with open(file_path) as f:
for line in f:
word = line.strip()
if len(word) > origin_len:
continue
if len(word) < min_length:
return
if check_same_letters(origin_map,word):
yield word
def find_longest_from_file(origin,file_path):
return iter_longest_from_file(origin,file_path).next()
if __name__ == '__main__':
origin = sys.argv[1] if len(sys.argv) > 1 else 'abcdefghijklmnopqrstuvwxyz'
print find_longest_from_file(origin,'words_by_len.txt')