按深度打印二叉树节点数据

class Node {    
    int value;
   Node left;
   Node right;
    public Node(int value, Node left, Node right) {        
        this.value = value;        
        this.left = left;        
        this.right = right;
   }
}

    public static void main(String[] args) {        
        // leaf node
       Node node4 = new Node(4, null, null);
       Node node5 = new Node(5, null, null);
       Node node6 = new Node(6, null, null);
       Node node7 = new Node(7, null, null);        
        
        // node 2 and node 3
       Node node2 = new Node(2, node4, node5);
       Node node3 = new Node(3, node6, node7);        
        
        // root node
       Node root = new Node(1, node2, node3);        
        List<Node> list = new ArrayList<>();        
        list.add(root);
        
       printNode(list);
   }