Python字符串匹配算法KMP实例

本文实例讲述了Python字符串匹配算法KMP。分享给大家供大家参考。具体如下：

#!/usr/bin/env python

#encoding:utf8

def next(pattern):

p_len = len(pattern)

pos = [-1]*p_len

j = -1

for i in range(1, p_len):

while j > -1 and pattern[j+1] != pattern[i]:

j = pos[j]

if pattern[j+1] == pattern[i]:

j = j + 1

pos[i] = j

return pos

def kmp(ss, pattern):

pos = next(pattern)

ss_len = len(ss)

pattern_len = len(pattern)

j = -1

for i in range(ss_len):

while j > -1 and pattern[j+1] != ss[i]:

j = pos[j]

if pattern[j+1] == ss[i]:

j = j + 1

if j == pattern_len-1:

print 'matched @: %s' % str(i-pattern_len+1)

j = pos[j]

kmp(u'上海自来水来自海上海', u'上海')

希望本文所述对大家的Python程序设计有所帮助。