005_013 Python 寻找子序列 字符串应该用find 否则用KMP

#encoding=utf-8

print '中国'

#寻找子序列

#字符串应该用find 否则用KMP
def KnuthMorrisPratt(text, pattern):
pattern = list(pattern)
length = len(pattern)

shifts = [1] * (length + 1)
shift = 1
for pos, pat in enumerate(pattern):
while shift <= pos and pat != pattern[pos-shift]:
shift += shifts[pos-shift]
shifts[pos+1] = shift

startPos = 0
matchLen = 0
for c in text:
while matchLen == length or matchLen >= 0 and pattern[matchLen] != c:
startPos += shifts[matchLen]
matchLen -= shifts[matchLen]
matchLen += 1
if matchLen == length: yield startPos

for i in KnuthMorrisPratt([1,2,3,4,2,3],[2,3]):
print i