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

/*
判断字符串是否匹配，其中要注意*表示前一个字母可以任意出现多次。
用动规就好了
*/
class Solution {
public:
bool isMatch(string s, string p) {
int m = s.length(), n = p.length();
vector<vector<bool> > dp(m + 1, vector<bool> (n + 1, false));
dp[0][0] = true;
for (int i = 0; i <= m; i++)
for (int j = 1; j <= n; j++)
if (p[j - 1] == '*')
dp[i][j] = dp[i][j - 2] || (i > 0 && (s[i - 1] == p[j - 2] || p[j - 2] == '.') && dp[i - 1][j]);
else dp[i][j] = i > 0 && dp[i - 1][j - 1] && (s[i - 1] == p[j - 1] || p[j - 1] == '.');
return dp[m]
;
}
};