We have the best collection of Preorder Traversal MCQs and answer with FREE PDF. These Preorder Traversal MCQs will help you to prepare for any competitive exams like: BCA, MCA, GATE, GRE, IES, PSC, UGC NET, DOEACC Exams at all levels – you just have to practice regularly.

## Preorder Traversal MCQs

**1. What is the time complexity of pre-order traversal in the iterative fashion?**

a) O(1)

b) O(n)

c) O(logn)

d) O(nlogn)

**Answer: **O(n)

**2. For the tree below, write the pre-order traversal.**

a) 2, 7, 2, 6, 5, 11, 5, 9, 4

b) 2, 7, 5, 2, 6, 9, 5, 11, 4

c) 2, 5, 11, 6, 7, 4, 9, 5, 2

d) 2, 7, 5, 6, 11, 2, 5, 4, 9

**Answer: **2, 7, 2, 6, 5, 11, 5, 9, 4

**3. For the tree below, write the post-order traversal.**

b) 2, 7, 5, 2, 6, 9, 5, 11, 4

c) 2, 5, 11, 6, 7, 4, 9, 5, 2

d) 2, 7, 5, 6, 11, 2, 5, 4, 9

**Answer: **2, 5, 11, 6, 7, 4, 9, 5, 2

**4. What is the space complexity of the post-order traversal in the recursive fashion? (d is the tree depth and n is the number of nodes)**

a) O(1)

b) O(nlogd)

c) O(logd)

d) O(d)

**Answer: **O(nlogd)

**5. To obtain a prefix expression, which of the tree traversals is used?**

a) Level-order traversal

b) Pre-order traversal

c) Post-order traversal

d) In-order traversal

**Answer: **Pre-order traversal

**6. Consider the following data. The pre order traversal of a binary tree is A, B, E, C, D. The in order traversal of the same binary tree is B, E, A, D, C. The level order sequence for the binary tree is**

a) A, C, D, B, E

b) A, B, C, D, E

c) A, B, C, E, D

d) D, B, E, A, C

**Answer: **A, B, C, E, D

**7. Consider the following data and specify which one is Preorder Traversal Sequence, Inorder and Postorder sequences.**

S1: N, M, P, O, Q

S2: N, P, Q, O, M

S3: M, N, O, P, Q

a) S1 is preorder, S2 is inorder and S3 is postorder

b) S1 is inorder, S2 is preorder and S3 is postorder

c) S1 is inorder, S2 is postorder and S3 is preorder

d) S1 is postorder, S2 is inorder and S3 is preorder

**Answer: **S1 is inorder, S2 is postorder and S3 is preorder