void decode(String s, Node root) {        
    Node current = root;
    for (char c : s.toCharArray()) {           
        if (c == '0') {
            current = current.left;
        } else {
            current = current.right;
        }
        
        if (current != null && current.data != '\0') {
            System.out.print(current.data);
            current = root;
        }
        
    }
}