86 lines
1.9 KiB
Python
86 lines
1.9 KiB
Python
''' mbinary
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#########################################################################
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# File : sunday.py
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# Author: mbinary
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# Mail: zhuheqin1@gmail.com
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# Blog: https://mbinary.xyz
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# Github: https://github.com/mbinary
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# Created Time: 2018-07-11 15:26
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# Description: 字符串模式匹配, sunday 算法, kmp 的改进
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# pattern matching for strings using sunday algorithm
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#########################################################################
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'''
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def getPos(pattern):
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dic = {}
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for i, j in enumerate(pattern[::-1]):
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if j not in dic:
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dic[j] = i
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return dic
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def find(s, p):
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dic = getPos(p)
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ps = pp = 0
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ns = len(s)
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np = len(p)
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while ps < ns and pp < np:
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if s[ps] == p[pp]:
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ps, pp = ps+1, pp+1
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else:
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idx = ps + np-pp
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if idx >= ns:
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return -1
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ch = s[idx]
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if ch in dic:
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ps += dic[ch]+1-pp
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else:
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ps = idx+1
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pp = 0
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if pp == np:
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return ps-np
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else:
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return -1
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def findAll(s, p):
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ns = len(s)
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np = len(p)
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i = 0
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ret = []
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while s:
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print(s, p)
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tmp = find(s, p)
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if tmp == -1:
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break
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ret.append(i+tmp)
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end = tmp+np
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i += end
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s = s[end:]
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return ret
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def randStr(n=3):
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return [randint(ord('a'), ord('z')) for i in range(n)]
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def test(n):
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s = randStr(n)
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p = randStr(3)
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str_s = ''.join((chr(i) for i in s))
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str_p = ''.join((chr(i) for i in p))
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n1 = find(s, p)
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n2 = str_s.find(str_p) # 利用已有的 str find 算法检验
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if n1 != n2:
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print(n1, n2, str_p, str_s)
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return False
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return True
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if __name__ == '__main__':
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from random import randint
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n = 1000
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suc = sum(test(n) for i in range(n))
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print('test {n} times, success {suc} times'.format(n=n, suc=suc))
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