INT102-Horspool Algorithm

 

 1 def horsepool(S: str, P: str) -> tuple:
 2     n, m, M = len(S), len(P), 26
 3     shift_table = [m for _ in range(M)]
 4     for i in range(m - 1):
 5         shift_table[ord(P[i]) - ord('A')] = m - i - 1
 6     pos, ans, flag = 0, [], False
 7 
 8     while pos <= (n - m):
 9         j = m - 1
10         while j >= 0 and S[pos + j] == P[j]:
11             j -= 1
12         if j == -1:
13             flag = True
14             ans.append(pos)
15             pos += m
16         else:
17             pos += shift_table[ord(S[pos + m - 1]) - ord('A')]
18     if not flag:
19         print("Not find")
20     return flag, ans, shift_table
21 
22 
23 if __name__ == '__main__':
24     S = "AGCAATGAA"
25     P = "ATGAA"
26     flag, pos, table = horsepool(S, P)
27     print(flag)
28     print(pos)
29     print(table)

 

posted @ 2021-05-19 14:19  墨鳌  阅读(76)  评论(0)  编辑  收藏  举报