I have a doubt in this Question , please give me hint

Question

In a randomised BST is constructing  with 7 distinct elements . What is the probability that its Inorder and postOrder traversal are same

Answer 1

I think the answer is 1/(7!)

If any node (N) has a right child (R), then in-order will visit (N) before (R) and post-order will visit (R) before (N). Hence the only way the traversals are the same is if all the nodes have only left children.