正則表示式匹配

public boolean isMatch(String s, String p) {
        if (s == null || p == null)
            return false;

        int m = s.length(), n = p.length();
        boolean[][] dp = new boolean[m + 1][n + 1];
        dp[0][0] = true;
        for (int j = 1; j <= n; j++) {
            if (p.charAt(j - 1) == '*') {
                dp[0][j] = dp[0][j - 2];
            }
        }

        for (int i = 1; i <= m; i++) {
            for (int j = 1; j <= n; j++) {
                if (s.charAt(i-1) == p.charAt(j-1) || p.charAt(j-1) == '.') {
                    dp[i][j] = dp[i-1][j-1];
                } else if (p.charAt(j-1) == '*') {
                    if (s.charAt(i-1) == p.charAt(j-2) || p.charAt(j-2) == '.') {
                        dp[i][j] = dp[i][j-2] || dp[i-1][j-2] || dp[i-1][j];    // 抵消0、1、多
                    } else {
                        dp[i][j] = dp[i][j-2];
                    }
                }
            }
        }
        return dp[m][n];
    }