Data Structures and Algorithms - Old Questions
11. How do you transverse a binary tree? Discuss.
The tree traversal is a way in which each node in the tree is visited exactly once in a symmetric manner.
The binary tree can be traverse in 3 ways:
1.
Pre-order traversal
2.
In-order traversal
3. Post-order traversal
Pre-order Traversal
In Pre-Order traversal, the root node is visited before left child and right child nodes. In this traversal, the root node is visited first, then its left child and later its right child. This pre-order traversal is applicable for every root node of all subtrees in the tree.
Algorithm:
Until all nodes are traversed:- Step 1: Visit root node Step 2: Recursively traverse left sub-tree. Step 3: Recursively traverse right sub-tree. |
.
E.g.
The preorder traversal output of the given above tree is: A B D H I E C F G
In-order Traversal:
In In-Order traversal, the root node is visited between left child and right child. In this traversal, the left child node is visited first, then the root node is visited and later we go for visiting right child node. This in-order traversal is applicable for every root node of all subtrees in the tree. This is performed recursively for all nodes in the tree
Algorithm:
Until all nodes are traversed:- Step 1: Recursively traverse left sub-tree. Step 2: Visit root node Step 3: Recursively traverse right sub-tree. |
E.g.
The inorder traversal output of the given tree is: H D I B E A F C G
Post-order Traversal
In Post-Order traversal, the root node is visited after left child and right child. In this traversal, left child node is visited first, then its right child and then its root node. This is recursively performed until the right most node is visited.
Algorithm:
Until all nodes are traversed:- Step 1: Recursively traverse left sub-tree. Step 2: Recursively traverse right sub-tree. Step 3: Visit root node |
E.g.
The post-order traversal output of the given above tree is: H I D E B F G C A