正则表达式匹配.py

# -*- coding:utf-8 -*-
class Solution:
    # s, pattern都是字符串
    def match(self, s, pattern):
        # write code here
        if s is None or pattern is None:
            return False
        return self.matchCore(s,pattern)
 
    def matchCore(self, s, pattern):
        if s =="" and pattern =="":
            return True
        if s!="" and pattern=="":
            return False
        if len(pattern)>=2 and pattern[1] == '*':
            if s!="" and (pattern[0] == s[0] or pattern[0]=='.'):
                return self.matchCore(s[1:],pattern) or self.matchCore(s[1:],pattern[2:]) or self.matchCore(s,pattern[2:])
            else:
                return self.matchCore(s,pattern[2:])
        if s!="" and s[0] == pattern[0] or(pattern[0]=='.' and len(s)!=0):
            return self.matchCore(s[1:],pattern[1:])
        return False