2020数据结构小学期（一）——KMP匹配算法

1、 KMP模式匹配算法

输入：模式串，主串

功能要求：输出模式串的next值表，输出匹配结果

源码：

 1 def matchintg_KMP(t, p, prefix):
 2     n, m = len(t), len(p)
 3     j, i = 0, 0
 4     while j < n and i < m:
 5         if i == -1 or t[j] == p[i]:
 6             i, j = i + 1, j + 1
 7         else:
 8             i = prefix[i]
 9     if i == m:
10         return j - i
11     return -1
12 
13 
14 def prefix_table(p):
15     i, k, m = 0, -1, len(p)
16     prefix = [-1] * m
17     while i < m - 1:
18         if k == -1 or p[i] == p[k]:
19             i, k = i + 1, k + 1
20             if p[i] == p[k]:
21                 prefix[i] = prefix[k]
22             else:
23                 prefix[i] = k
24         else:
25             k = prefix[k]
26     return prefix
27 
28 
29 if __name__ == '__main__':
30     # t = "ababcabcacbab"
31     # p = "abcac"
32     t = input("请输入主串：")
33     p = input("请输入模式串：")
34     pnext = prefix_table(p)
35     print("模式串next表：", pnext)
36     print("匹配结果：", matchintg_KMP(t, p, pnext))

posted on 2020-09-09 19:24 pjhhh 阅读(199) 评论(0) 编辑收藏举报