If you are given two traversal sequences, can you construct the binary tree?

It depends on what traversals are given. If one of the traversal methods is Inorder then the tree can be constructed, otherwise not.

👁 Mirror

Therefore, following combination can uniquely identify a tree.

• Inorder and Preorder. 
• Inorder and Postorder. 
• Inorder and Level-order. 

A unique binary tree cannot always be constructed using:

• Postorder and Preorder. 
• Preorder and Level-order. 
• Postorder and Level-order. 

For example, Preorder, Level-order and Postorder traversals are same for the trees given in above diagram. 

• Preorder Traversal = AB 
• Postorder Traversal = BA 
• Level-Order Traversal = AB 

So, even if all three traversals (Preorder, Postorder and Level-order) are given, the tree cannot be uniquely constructed.