public static BinTreeNode test10(BinTreeNode head,BinTreeNode node1,BinTreeNode node2){
        if (head==null||head==node1||head==node2) {
            return head;
        }
        BinTreeNode left = test10(head.left, node1, node2);
        BinTreeNode right = test10(head.right, node1, node2);
        if (left!=null&&right!=null) {
            return head;
        }
        return left!=null?left:right;
    }