forked from shuboc/LeetCode-2
-
Notifications
You must be signed in to change notification settings - Fork 0
/
regular-expression-matching.py
131 lines (116 loc) · 4.42 KB
/
regular-expression-matching.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
# Time: O(m * n)
# Space: O(n)
#
# Implement regular expression matching with support for '.' and '*'.
#
# '.' Matches any single character.
# '*' Matches zero or more of the preceding element.
#
# The matching should cover the entire input string (not partial).
#
# The function prototype should be:
# bool isMatch(const char *s, const char *p)
#
# Some examples:
# isMatch("aa","a") -> false
# isMatch("aa","aa") -> true
# isMatch("aaa","aa") -> false
# isMatch("aa", "a*") -> true
# isMatch("aa", ".*") -> true
# isMatch("ab", ".*") -> true
# isMatch("aab", "c*a*b") -> true
#
# dp with rolling window
class Solution:
# @return a boolean
def isMatch(self, s, p):
k = 3
result = [[False for j in xrange(len(p) + 1)] for i in xrange(k)]
result[0][0] = True
for i in xrange(2, len(p) + 1):
if p[i-1] == '*':
result[0][i] = result[0][i-2]
for i in xrange(1,len(s) + 1):
if i > 1:
result[0][0] = False
for j in xrange(1, len(p) + 1):
if p[j-1] != '*':
result[i % k][j] = result[(i-1) % k][j-1] and (s[i-1] == p[j-1] or p[j-1] == '.')
else:
result[i % k][j] = result[i % k][j-2] or (result[(i-1) % k][j] and (s[i-1] == p[j-2] or p[j-2] == '.'))
return result[len(s) % k][len(p)]
# dp
# Time: O(m * n)
# Space: O(m * n)
class Solution2:
# @return a boolean
def isMatch(self, s, p):
result = [[False for j in xrange(len(p) + 1)] for i in xrange(len(s) + 1)]
result[0][0] = True
for i in xrange(2, len(p) + 1):
if p[i-1] == '*':
result[0][i] = result[0][i-2]
for i in xrange(1,len(s) + 1):
for j in xrange(1, len(p) + 1):
if p[j-1] != '*':
result[i][j] = result[i-1][j-1] and (s[i-1] == p[j-1] or p[j-1] == '.')
else:
result[i][j] = result[i][j-2] or (result[i-1][j] and (s[i-1] == p[j-2] or p[j-2] == '.'))
return result[len(s)][len(p)]
# iteration
class Solution3:
# @return a boolean
def isMatch(self, s, p):
p_ptr, s_ptr, last_s_ptr, last_p_ptr = 0, 0, -1, -1
last_ptr = []
while s_ptr < len(s):
if p_ptr < len(p) and (p_ptr == len(p) - 1 or p[p_ptr + 1] != '*') and \
(s_ptr < len(s) and (p[p_ptr] == s[s_ptr] or p[p_ptr] == '.')):
s_ptr += 1
p_ptr += 1
elif p_ptr < len(p) - 1 and (p_ptr != len(p) - 1 and p[p_ptr + 1] == '*'):
p_ptr += 2
last_ptr.append([s_ptr, p_ptr])
elif last_ptr:
[last_s_ptr, last_p_ptr] = last_ptr.pop()
while last_ptr and p[last_p_ptr - 2] != s[last_s_ptr] and p[last_p_ptr - 2] != '.':
[last_s_ptr, last_p_ptr] = last_ptr.pop()
if p[last_p_ptr - 2] == s[last_s_ptr] or p[last_p_ptr - 2] == '.':
last_s_ptr += 1
s_ptr = last_s_ptr
p_ptr = last_p_ptr
last_ptr.append([s_ptr, p_ptr])
else:
return False
else:
return False
while p_ptr < len(p) - 1 and p[p_ptr] == '.' and p[p_ptr + 1] == '*':
p_ptr += 2
return p_ptr == len(p)
# recursive
class Solution4:
# @return a boolean
def isMatch(self, s, p):
if not p:
return not s
if len(p) == 1 or p[1] != '*':
if len(s) > 0 and (p[0] == s[0] or p[0] == '.'):
return self.isMatch(s[1:], p[1:])
else:
return False
else:
while len(s) > 0 and (p[0] == s[0] or p[0] == '.'):
if self.isMatch(s, p[2:]):
return True
s = s[1:]
return self.isMatch(s, p[2:])
if __name__ == "__main__":
print Solution3().isMatch("abab", "a*b*")
print Solution().isMatch("aaaaaaaaaaaaab", "a*a*a*a*a*a*a*a*a*a*c")
print Solution().isMatch("aa","a")
print Solution().isMatch("aa","aa")
print Solution().isMatch("aaa","aa")
print Solution().isMatch("aa", "a*")
print Solution().isMatch("aa", ".*")
print Solution().isMatch("ab", ".*")
print Solution().isMatch("aab", "c*a*b")