[LeetCode]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 == 0)
{
return *s == 0;
}
//不等于'*'的情况
if(*(p + 1) != '*')
{
//若此时*s和*p相等，则进行isMatch(s+1, p+1)的判断
if(*s && (*s == *p || *p == '.'))
{
return isMatch(s + 1, p + 1);
}
return false;
}
else
{
for(; *s && (*s == *p || *p == '.'); s++)
{
//'*' 不再匹配前面的字符.
if(isMatch(s, p + 2))
{
return true;
}
//'*'接着匹配前面的字符.继续for循环
}
//'*'匹配结束
return isMatch(s, p + 2);
}

}
};