字符串模式匹配

1. 单模匹配

1.1 KMP（Knuth-Morris-Pratt）

 1 from typing import List
 2 
 3 
 4 class KMP:
 5     def _next(self, pattern: str) -> List[int]:
 6         """
 7         计算next数组
 8         """
 9         next = [-1] * len(pattern)
10         i, j = -1, 0
11         while j < len(pattern) - 1:
12             if i == -1 or pattern[i] == pattern[j]:
13                 i += 1
14                 j += 1
15                 next[j] = i if pattern[i] != pattern[j] else next[i]  # 这里相对朴素方法已经有了优化
16             else:
17                 i = next[i]
18         return next
19 
20     def match(self, string: str, pattern: str) -> int:
21         """
22         返回第一个匹配位置，失败返回len(string)
23         """
24         next = self._next(pattern)
25         i, j = 0, 0
26         while i < len(string) and j < len(pattern):
27             if j == -1:
28                 i += 1
29                 j += 1
30             elif string[i] == pattern[j]:
31                 i += 1
32                 j += 1
33             else:
34                 j = next[j]
35         return i - j if j == len(pattern) else i
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1.2 BM（Boyer-Moore）

1.3 Sunday

2. 多模匹配

posted @ 2020-03-09 01:03  wory  阅读(174)  评论(0)    收藏  举报