Python字符串匹配算法KMP实例

#!/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')