private int index = 0;
    void decode(String s, Node root) {
        char[] chars = s.toCharArray();
        StringBuilder sb = new StringBuilder();
        while (index < chars.length) {
            Character ss = navigateAndGet(chars, root);
            if (ss != null) {
                sb.append(ss);
            }
        }
        System.out.print(sb);
    }

    private Character navigateAndGet(char[] chars, Node node) {
        if (node.left == null && node.right == null) {
            return node.data;
        }
        if (index == chars.length) {
            return null;
        }
        Node nextNode;
        if (chars[index] == '0') {
            nextNode = node.left;
        } else {
            nextNode = node.right;
        }
        index++;
        return navigateAndGet(chars, nextNode);
    }