Data Structures MCQs with Answers for Practice

Learning data structures and algorithms is fundamental for any software developer from any domain. These concepts form the backbone for most of the profiles in IT.

With the increase in job opportunities, the competition has also increased. Now, top-tech companies hire software engineers who are highly skilled and possess advanced knowledge of data structures and algorithms.

Mastering data structures such as arrays, linked lists, stacks, and trees, along with algorithms for sorting, searching, and traversing, enhances problem-solving skills and logical thinking.

Practicing MCQs on data structures and algorithms reinforces knowledge and problem-solving skills. These MCQs are crucial if you’re on a self-learning journey. You can assess your knowledge and see where you stand.

These MCQs on DSA cover basic operations and data structures, linear and non-linear data structures, queue operations, algorithm applications, and so on.

Overall, these questions aim to test and reinforce knowledge in various areas including the types and operations of data structures, algorithmic applications, and fundamental programming principles crucial for software developers.

We have brought you a collection of 40 data structure MCQs to strengthen your preparation. These algorithm interview questions are commonly asked in numerous top-tech FAANG companies’ interview processes.

Also Read: Top Data Structures and Algorithms Interview Questions

Data Structures MCQs with Answers

Data structure MCQs help you understand vast topics precisely and get yourself prepared enough to crack software engineer interviews in one go.

We have enlisted some coding interview questions with their answers that are commonly asked in top tech companies like FAANG+.

1. Choose the invalid operation for the data structure.

1. Operations that manipulate data in some manner
2. Operations that evaluate computation
3. Operations that track the occurrence of objects
4. Operations that assess syntax error

Answer: a. Operations that manipulate data in some manner

2. ______ is the outcome of the following code snippet.

1. 10
2. 9
3. 4
4. 5

Answer: b. 9

3. In C, Syring is represented in memory as

1. Same as other primitive data
2. The object of any class
3. LinkedList of characters in a database
4. An array of characters

Answer: d. An array of characters

4. Choose the correct linear data structure.

1. Graphs
2. Array
3. Binary Trees
4. AVL Trees

Answer: b. Array

5. From the type of queue given, choose the odd one out.

1. Single-ended queue
2. Priority queue
3. Circular queue
4. Ordinary queue

Answer: a. Single-ended queue

6. What is the correct output for the given code snippet?

1. Syntax Error
2. 15
3. 2
4. 3

Answer: d. 3

7. ________ data structures used to implement maps in C++.

1. AVL Trees
2. Hash Tables
3. Binary Search Trees
4. Red-Black Trees

Answer: d. Red-Black Trees

8. Which of the given applications are Topological SOrts of a graph?

1. OD Deadlock Detection
2. Sentence Ordering
3. Course Scheduling
4. All of the above

Answer: d. All of the above

9. Choose the correct data structure used to match the parenthesis.

1. n-ary tree
2. Priority queue
3. Ordinary queue
4. Stack

Answer: d. Stack

10. ________ algorithm is used in the top tree data structures.

1. Branch
2. Greedy
3. Divide and Conquer
4. None of the above

Answer: c. Divide and Conquer

11. Choose the value of the end (rear) in case the queue is full.

1. MAX – 1
2. MAX + 1
3. Null (zero)
4. None of the above

Answer: a. MAX – 1

12. Choose the correct value set at the front and rear ends throughout initializing a Queue.

1. -1
2. 1
3. 0
4. Infinity

Answer: a. -1

13. Which algorithms are used for string and pattern-matching problems?

1. KMP Algorithm
2. Rabin Karp
3. Z Algorithm
4. All of the above

Answer: d. All of the above

14. Name the condition when a pop() operation is called on an empty queue.

1. Syntax Error
2. Garbage Value
3. Overflow
4. Underflow

Answer: d. Underflow

15. Choose the application that implements a circular linked list.

1.  Allocating CPU to resources
2. To perform a functional call
3. Incorporate hash tables
4. All of the above

Answer: a.  Allocating CPU to resources

16. Choose the odd one out of computer languages: Linux, Java, and C++.

1. Linux
2. Java
3. C++
4. None of the above

Answer: a. Linux

17. Which of the following comes under linear data structure?

1. AVL trees
2. Binary trees
3. Array
4. Graphs

Answer: c. Array

18. If the Queue is non-empty, choose the correct application condition from the following.

1. Rear = front
2. Unpredictable
3. Rear > front
4. Rear < front

Answer: c. Rear > front

19. Choose the main purpose of OOP inheritance.

1. Prevent data abstraction
2. Prevent data deletion
3. Define exceptions
4. Establish a parent-child relationship between classes

Answer: d. Establish a parent-child relationship between classes

20. _________ principle ensures that only necessary information is visible to the exterior world.

1. Polymorphism
2. Abstraction
3. Information hiding
4. Encapsulation

Answer: c. Information hiding

21. Which sorting algorithms offer the best time complexity over the worst-case scenario?

1. Bubble sort
2. Selection sort
3. Merge sort
4. None of the above

Answer: c. Merge sort

22. Choose from the following which is not a type of queue.

1. Circular queue
2. Single-ended queue
3. Ordinary queue
4. None of the above

Answer: b. Single-ended queue

22. Which of the following is needed to evaluate whether an expression comprises a balanced parenthesis?

1. Array
2. Stack
3. Queue
4. All of the above

Answer: b. Stack

23. The emptiness of a Queue can be precisely verified by which of the following ‘C’ functions?

int empty(Q*P)

{

if (P->R==-1)

return (1);

return (0);

}

int full(Q*P)

{

if (P<-R==MAX-1)

return (1);

return (0);

}

int empty(Q*P)

{

if (P<-R>==-1)

return (0);

return (1);

}

int full (Q*P)

{

if (P<-R==-1)

return (1);

return (0);

}

Answer: a.

int empty(Q*P)

{

if (P->R==-1)

return (1);

return (0);

}

24. If statements can have multiple ________.

1. IF ELSE
2. CASE
3. ELSE
4. ELSEIF

Answer: d. ELSEIF

25. The root directory of a disk is placed at

1. Fixed address in the primary memory
2. Anywhere on the disk
3. Fixed place on the system disk
4. Depending on the disk type

Answer: c. Fixed place on the system disk

26. Within a switch statement, which of the following you can use?

1. Break but not continue
2. Both continue and break
3. Continue but not break
4. Neither continue nor break

Answer: a. Break but not continue

27. _______ function is used to append the character at the back of a string in C++ programming language.

1. push()
2. append()
3. push_back()
4. insert()

Answer: push_back()

28. Determine the correct output for the given postfix expression: 6324+___*?

1. –12
2. 18
3. –18
4. 12

Answer: c. –18

29. When there is a need for quicker append and pop operations for both ends of the container, the data structure used in Python over a list is ______.

1. stack
2. queue
3. dequeue
4. a or b

Answer: c. dequeue

30. Choose the correct operation performed by the pops function on the ‘stackname’ stack using the given code.

def pops(stackname)

   return len(stackname)

1. Return the size of stack
2. Pop element from the stack
3. Push the element on the bottom of the stack
4. None of the above

Answer: a. Return the size of stack

31. Stack is the optimal data structure implemented to solve

1. Tree
2. Heap
3. Stack
4. Priority

Answer: c. Stack

32. If a*b is written as *ab, we call it ________.

1. Polish notation
2. Inflix expression
3. Postfix expression
4. Polish expression

Answer: a. Polish notation

33. __________ add an element to the top of a stack.

1. Pop
2. Push
3. IsEmpty
4. Peek

Answer: b. Push

34. Choose the correct output of the given snippet.

1. 3
2. 6
3. 1 2 3
4. 3 2 1

Answer: 3 2 1

35. ______ is the data structure used to complement recursion.

1. Queue
2. List
3. Array
4. Stack

Answer: d. Stack

36. A _________ notation is implemented for writing an expression where _______ operators are written in between the operands.

1. Infix, binary
2. Infix, tertiary
3. Postfix, infix
4. Prefix, postfix

Answer: a. Infix, binary

37. _______ and ________ are the two fundamentals implemented on the stack.

1. PUSH & POP
2. TOP & HEAD
3. BACK & FRONT
4. ENQUEUE & DEQUEUE

Answer: a. PUSH & POP

38. Elements ‘6’, ‘9’, ‘1’, and ‘5’ are placed in a queue and then deleted one by one at a time. Choose the correct order of their removal.

1. 6915
2. 5196
3. 6915
4. 9615

Answer: c. 6915

39. Calculate the outcome of the following postfix expression: 793+4/*.

1. 21
2. 10
3. 33
4. 49

Answer: a. 21

40. ________ data structures can be used to implement queues.

1. LinkedList
2. Stack
3. Arrays
4. All of the above

Answer: All of the above

Learn Data Structures and Crack Tough Interviews with IK!

Mastering Data Structures and Algorithms (DSA) is crucial as they form the backbone of many job profiles in software development, data analysis, and more. Our Early Engineering Course is designed to give you a strong foundation in DSA, equipping you with the skills needed to excel in technical interviews and on the job.

Our instructors teach you Data Structures and Algorithms from sorting algorithms, recursion, Trees, Graphs, and more. These concepts are fundamental to other major job profiles as well. For instance, Back end engineering.

Aspiring Data Scientists also learn Data Structures and Algorithms from our Data Science course.

FAQs: Data Structures and Algorithms

What is data structure suitable for?
Data structure is best for data retrieval, storage, processing, and organization.

Why create a data structure?
Data structure enables users to easily access and perform work within the data based on their requirements.

Who is the father of data structure and algorithm?
Donald Knuth from Stanford University is known as the father of data structure and algorithms.

What is an algorithm in data structure?
An algorithm refers to a procedure or list of instructions to conduct particular actions, solve problems, or perform a computation.

What is a flowchart in data structure?
A flowchart refers to a structure or diagram that determines a process, computer algorithm, or system. It is used to represent complex data in simpler form for a better understanding of the concept.

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