class Solution {
    public boolean isMatch(String s, String p) {

       if(p.isEmpty() && s.isEmpty()) {
            return true;
        }

        if(p.isEmpty() && !s.isEmpty()) {
            return false;
        }

        char pChar = p.charAt(0);
        boolean isWildcard = false;

        if(p.length() > 1) {
            isWildcard = p.charAt(1) == '*';
        }
        if(pChar == '.') {
            return validateDot(isWildcard, s, p);

        } else if (pChar >= 'a' && pChar <= 'z') {
            return validateDigit(pChar, isWildcard, s, p);
        } else {
            return false;
        }
    }

    private boolean validateDigit(char c, boolean isWildcard, String s, String p) {

        if(!s.isEmpty()) {
            if (c == s.charAt(0)) {
                int sumChars = sumSequentialChars(c, s);
                if (!isWildcard) {
                    return isMatch(s.substring(1), p.substring(1));
                } else {
                    return isMatch(s, p.substring(2)) || isMatch(s.substring(sumChars), p.substring(2)) || isMatch(s.substring(1), p);
                }
            }
            if (c != s.charAt(0) && isWildcard) {
                return isMatch(s, p.substring(2));
            }
        } else if(isWildcard) {
            return isMatch(s, p.substring(2));
        }
        return false;
    }

    private boolean validateDot(boolean isWildcard, String s, String p) {
        if(s.isEmpty()) {
            if(!isWildcard) {
                return false;
            }
        }
        if(s.isEmpty()) {
            return isMatch(s, p.substring(2));
        }
        if(!isWildcard) {
            return isMatch(s.substring(1), p.substring(1));
        } else {
            int sumChars = sumSequentialChars(s.charAt(0), s);
            return isMatch(s, p.substring(2)) || isMatch(s.substring(sumChars), p.substring(2))
                    || isMatch(s.substring(1), p);
        }
    }

    private int sumSequentialChars(char c, String s) {
        int res = 0;
        while(res < s.length() && c == s.charAt(res)) {
            res++;
        }
        return res;
    }
}