Regular Expression Matching

'.'

'*'

'.' 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

class Solution {
public:
bool isMatch(const char *s, const char *p) {
if(*p == NULL){
return *s == NULL;
}
if(*(p+1) != '*'){
if(*s != NULL && (*s == *p || *p == '.')){
return isMatch(++s,++p);
}
else
return false;
}
else{
while(*s != NULL && (*p == *s || *p == '.')){
if(isMatch(s,p+2)){
return true;
}
s++;
}
return isMatch(s, p+2);
}
}
};