Binary Tree

Question

What is the number of binary trees with 4 nodes which when traversed in pre-order gives the sequence 1,2,3,4?

Comments

Because it's binary tree not binary search tree :)

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yes
thanks all

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@srestha  @ Mk Utkarsh   I think the answer be 6 since the question has mentioned about the preorder traversal  ?

Answer 1

$(2n)!/(n+1)!*n!$

where n= no. of nodes

 In this case $(8)!/(4+1)!*4!$ = 14