Regular Expression Matching

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

如果P[j+1]!='*'，S[i] == P[j]=>匹配下一位(i+1, j+1)，S[i]!=P[j]=>匹配失败；

如果P[j+1]=='*'，S[i]==P[j]=>匹配下一位(i+1, j+2)或者(i, j+2)，S[i]!=P[j]=>匹配下一位(i,j+2)。

bool isMatch(const char *s, const char *p)
{
if (*p == '\0')
return *s == '\0';

if (*(p + 1) == '*')
{
while (*s != '\0' && (*s == *p || *p == '.'))
{
if (isMatch(s, p + 2))
{
return true;
}
s++;
}
return isMatch(s, p + 2);
}
else  if (*s != '\0' && (*s == *p || *p == '.'))
{
return isMatch(s + 1, p + 1);
}

return false;
}