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));    }};