Regular Expression Matching_LeetCode

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

My Solution:
class Solution:

def isEqual(self,a,b):

if a=="." or b==".":

return True

else:

return True if a==b else False

def isMatch(self,S,P):

N=len(S)

M=len(P)

S+="?"

P+="?"

DP=[[False for i in range(M+1)]for j in range(N+1)]

DP
[M]=True

for j in range(M-1,-1,-1):#Pattern

for i in range(N,-1,-1):#String

if P[j]=="*":

continue

if P[j+1]!="*":

if self.isEqual(P[j],S[i]):

if i<N:

DP[i][j]=DP[i+1][j+1]

else:

if DP[i][j+2]:

DP[i][j]=True

continue

cnt=0

while 1:

if i+cnt+1>N:

break

if not self.isEqual(S[i+cnt],P[j]):

break

if DP[i+1+cnt][j+2]==True:

DP[i][j]=True

break

cnt+=1

return DP[0][0]