10. Regular Expression Matching

class Solution {
public:
bool isMatch(string s, string p) {
if(p.empty()) return s.empty();
else if(p[1]=='*')
return isMatch(s,p.substr(2))||!s.empty()&&((s[0]==p[0]||p[0]=='.')&&isMatch(s.substr(1),p));
else
return !s.empty()&&(s[0]==p[0]||p[0]=='.')&&isMatch(s.substr(1),p.substr(1));
}
};