algorithm-in-python/string/KMP.py

59 lines
1.3 KiB
Python

#coding: utf-8
''' mbinary
#########################################################################
# File : KMP.py
# Author: mbinary
# Mail: zhuheqin1@gmail.com
# Blog: https://mbinary.coding.me
# Github: https://github.com/mbinary
# Created Time: 2018-12-11 14:02
# Description:
#########################################################################
'''
def getPrefixFunc(s):
'''return the list of prefix function of s'''
length = 0
i = 1
n = len(s)
ret = [0]
while i<n:
if s[i]==s[length]:
length +=1
ret.append(length)
i+=1
else:
if length==0:
ret.append(0)
i+=1
else:
length = ret[length-1]
return ret
def findAll(s,p):
pre = getPrefixFunc(p)
i = j =0
n,m = len(s),len(p)
ret = []
while i<n:
if s[i]==p[j]:
i+=1
j+=1
if j==m:
ret.append(i-j)
j=pre[j-1]
else:
if j==0: i+=1
else: j = pre[j-1]
return ret
def randStr(n=3):
return [randint(ord('a'),ord('z')) for i in range(n)]
if __name__ =='__main__':
from random import randint
s = randStr(50)
p = randStr(1)
print(s)
print(p)
print(findAll(s,p))