Q. What do you understand by the tree traversal? Write down the procedure for traversing a binary tree in preorder and execute it on the following tree. 

Ans:

The algorithm walks through tree data structure and performs some calculation at each node in the tree. This procedure of walking through the tree is called a tree traversal.

There are basically two different methods in which to visit systematically all the nodes of a tree-the depth-first traversal and the breadth-first traversal. Certain depth- first traversal methods happen frequently enough that they are given names of their own: preorder traversal, inorder traversal and postorder traversal.

The algorithm for traversing a tree in preorder is written as follows:-

i.     Process the root R.

ii.    Traverse left sub tree of R in preorder.
iii.   Traverse right sub tree of R in preorder. The preorder for the given tree is as follows:-

A   L1  R1

A  B    L1l  L1R  R1

A  B    D      L1R  R1

A  B    D      E       R1

A  B    D      E       C    R1L  R1R

A  B      D         E            C      F       R1R

A  B          D         E          C            F       G