##### 1) A Binary Tree can have

- Can have 2 children
- Can have 1 children
- Can have 0 children
- All

Answer: 4

Explanation: Binary tree can have at most 2 children.

##### 2) Height of Height of a binary tree is

- MAX( Height of left Subtree, Height of right subtree)+1
- MAX( Height of left Subtree, Height of right subtree)
- MAX( Height of left Subtree, Height of right subtree)-1
- None

Answer: 1

##### 3) Postfix expression for (A+B) *(C+D) is

- A B C * + D +
- A B + C D + *
- ABCD++*
- None

Answer: 2

In postfix form two operands come together then operator. For example, in A+B, A and B are two operands and + is one operator and A+B is in infix form. Hence, in postfix of A+B will be AB+.

Let’s consider the question above

(A+B) *(C+D)//this expression is in infix form

First get A and B operand together then operator +. Similarly, for C and D

(AB+) * (CD+)

now consider AB+ and CD+ as two operands. Take them together then * operator.

(AB+) (CD+) *

Remove brackets.

AB+CD+*

So, AB+CD+* is the postfix expression of (A+B) *(C+D) infix expression.

##### 4) True statements about AVL tree are

- It is a binary search tree.
- Left node and right node differs in height by at most 1 unit
- Worst case time complexity is O(log2n)
- Worst case time complexity is O(n)

**Answer: 1, 2 and 3**

A side note: AVL tree is a self balancing binary tree and named after **inventors Adelson-Velsky and Landis …wikipedia..**

##### 5)Match the following for binary tree traversal

(1) Pre Order | (A)Left Right Root |

(2) In Order | (B)Left Root Right |

(3) Post Order | (C)Root Left Right |

- 1 → A, 2 → B, 3 → C
- 1 → C, 2 → B, 3 → A
- 1 → A, 2 → C, 3 → B
- 1 → B, 2 → A, 3 → C

Answer:2