[Leetcode]10. 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(string s, string p) {
return isMatch(s.c_str(), p.c_str());
}

bool isMatch(const char *s, const char *p) {
if (*p == '\0')
return *s == '\0';
// next char is not '*', then must match current character
if (*(p + 1) != '*') {
if (*p == *s || (*p == '.' && *s != '\0'))
return isMatch(s + 1, p + 1);
else
return false;
}
else { // next char is '*'
while (*p == *s || (*p == '.' && *s != '\0')) {
if (isMatch(s, p + 2))
return true;
s++;
}
return isMatch(s, p + 2);
}
}
};