reconstructing a tree from its preorder and postorder lists

Question

Consider the situation where you have two lists of nodes of which all you know is that one is a representation of a preorder traversal of some tree and the other a represent

Answer 1

Create a binary tree with this restriction that has at least one node that this node has only one child(right or left ,there is no difference).

Now, write its Preorder and Postorder lists. then try to reconstructing the tree from these lists. and you realize that on that node you cannot decide that its child is right or left.