Binary tree important questions and answers in “**Data structures**.” These 2 mark Q & A will be used by Engineering stream and all kind of computer related students.

**BINARY TREE**

1. Define a binary tree.

A binary tree is a tree which has nodes either empty or not more than two child nodes, each of which may be a leaf node.

2. Define a full binary tree.

A full binary tree is a tree in which all the leaves are on the same level and every non-leaf node has exactly two children.

3. Define a complete binary tree.

A **complete binary tree** is a tree in which every non-leaf node has exactly two children not necessarily to be on the same level.

4. Define a right-skewed binary tree.

A right-skewed binary tree is a tree, which has only right child nodes.

5.State the properties of a binary tree.

- Maximum No.of nodes on level n of a binary tree is2
^{ (n-1),}where n>=1. - Maximum No.of nodes in a binary tree of height is 2
^{(n-1)}, where n>=1. - For any non-empty tree, nl=nd+l, where nl is the number of leaf nodes and nd is the no.of nodes of degree 2.

6.What are the different ways of representing a binary tree?

- Linear representation using arrays.
- Linked representation using pointers.

7.State the merits of linear representation of a tree.

- Store methods are easy and can be easily implemented in arrays.
- When the location of the parent /child node is known, other one can be determined easily.
- It requires static memory allocation, so it is easily implemented in all programming languages

8.State the demerits of linear representation of a tree.

- Insertions and deletions are tougher.
- Processing consumes excess of time.
- Slow data movements up and down the array.

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9. Define Traversal.

Traversal is an operation which can be performed on a binary tree by visiting all the nodes exactly once.

**Inorder **: traversing the Left sub-tree(LST) , visiting the root and finally traversing the Right sub tree(RST).

**Preorder :** visiting root, traversing Left sub-tree(LST) and finally traversing Right sub tree(RST).

**Postorder** :traversing Left sub-tree(LST), then Right sub tree(RST) and finally visiting root.

10. What are the tasks performed while traversing a binary tree?

- Visiting a node.
- Traverse the left structure.
- Traverse the right structure.

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11.What are the tasks performed during** preorder** traversal?

- Process the root node.
- Traverse the left sub-tree.
- Traverse the right sub-tree.

Ex : +AB

12. What are the tasks performed during inorder traversal?

- Traverse the left sub-tree.
- Process the root node.
- Traverse the right sub-tree.

Ex:A+B

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13. What are the tasks performed during postorder traversal?

- Traverse the left sub-tree.
- Traverse the right sub-tree.
- Process the root node.

Ex: AB+.

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14. Define **binary search tree**.

A binary search tree is a special binary tree, which is either empty or if it is empty it should satisfy the conditions given below:

- Every node has a value and no two nodes should have the same value.
- The value in any left sub-tree is less than the value of its parent node.
- The value in any right sub-tree is greater than the value of its parent node.