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Pal.py
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Pal.py
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from Trie import *
import re
import sys
def reverse(string):
return string[::-1]
def is_palindrome(word):
return word == reverse(word)
def get_palindromes(filename, length, function, regex):
def generate(root, remainder, front, depth):
if depth <= 0:
return
if remainder == "":
function(root)
return
if front:
# [ root | remainder]
# [merwen | redniamer + root + remainder]
candidates = backward.find_from_pref(remainder)
for danc in candidates:
newroot = reverse(danc) + reverse(remainder) + " " + root
generate(newroot, danc, False, depth-1)
# [ root | remainder ]
# [mer + root + rem | ainder]
for i in range(len(remainder)+1):
if backward.is_word(remainder[0:i]):
newroot = reverse(remainder[0:i]) + " " + root
newrem = remainder[i:]
generate(newroot, newrem, True, depth-1)
else:
# [remainder | root]
# [remainder + root + redniamder | newrem]
candidates = forward.find_from_pref(remainder)
for cand in candidates:
newroot = root + " " + remainder + cand
generate(newroot, cand, True, depth-1)
# [remainder | root ]
# [remain | der + root + red]
for i in range(1,len(remainder)+1):
if forward.is_word(remainder[0:i]):
newroot = root + " " + remainder[0:i]
newrem = remainder[i:]
generate(newroot, newrem, False, depth-1)
return
try:
dictionary = open(filename, 'r')
except:
print "Error: invalid dict file."
sys.exit()
forward = Trie()
backward = Trie()
for word in dictionary:
if re.compile(regex).match(word):
forward.insert(word.strip())
backward.insert(word[::-1].strip())
dictionary.close()
for word in forward.find_words():
for i in range(len(word)):
if is_palindrome(word[0:i]):
generate(word, word[i:], True, length)
for i in reversed(range(len(word))):
if is_palindrome(word[i:]):
generate(word, reverse(word[0:i]), False, length)