Data Structures and Algorithms Multiple Choice Questions (MCQs)
We have compiled a list of 100+ questions with answers from Data Structures and Algorithms that help you to check your basic knowledge of data structures and prepare for competitive exams. All these multiple choice questions are prepared by the subject experts from authentic resources. Attempt all the questions and check your Data Structures and Algorithms knowledge online. This category contains questions from basic concepts of data structure.
Following are the important multiple choice questions with answers from the Data Structures and Algorithms section. You can choose the correct answer from option A, B, C and D.
Data Structures & Algorithms MCQs Practice MCQ Question and Answer
1
Which data structure uses LIFO (Last In First Out) principle?
Answer & Solution
Answer: Option B
Stack follows LIFO, where the last inserted element is removed first.
2
What is the time complexity of binary search in a sorted array?
Answer & Solution
Answer: Option B
Binary search cuts the array in half at each step, giving O(log n) complexity.
3
Which data structure is used for implementing recursion?
Answer & Solution
Answer: Option C
The function call stack is used to implement recursion in most programming languages.
4
Which sorting algorithm has the best average-case time complexity?
Answer & Solution
Answer: Option B
Quick Sort offers O(n log n) average-case performance, making it efficient in practice.
5
In which traversal is a binary tree processed in left-root-right order?
Answer & Solution
Answer: Option A
Inorder traversal processes the left subtree, then root, and then right subtree.
6
Which data structure allows inserting and deleting elements from both ends?
Answer & Solution
Answer: Option B
Deque (Double-Ended Queue) allows insertion and deletion from both front and rear ends.
7
Which data structure is most efficient for priority-based scheduling?
Answer & Solution
Answer: Option C
Heap supports priority queues efficiently using its tree-based structure.
8
Which traversal is used in breadth-first search of a tree or graph?
Answer & Solution
Answer: Option D
Level Order traversal corresponds to breadth-first search.
9
Which of the following is not a stable sorting algorithm?
Answer & Solution
Answer: Option C
Quick Sort is not stable as it may change the order of equal elements.
10
Which data structure is used in the implementation of BFS (Breadth First Search)?
Answer & Solution
Answer: Option B
BFS uses a queue to explore nodes level by level.
11
Which data structure uses hashing for fast access of data?
Answer & Solution
Answer: Option B
Hash tables use a hash function to map keys to values for fast data retrieval.
12
Which of these is not a self-balancing binary search tree?
Answer & Solution
Answer: Option D
A regular Binary Search Tree is not self-balancing.
13
Which of the following has the worst-case time complexity of O(n^2)?
Answer & Solution
Answer: Option C
Quick Sort has a worst-case time of O(n^2) when the pivot is poorly chosen.
14
Which of the following is true for a doubly linked list?
Answer & Solution
Answer: Option C
In a doubly linked list, each node points to both its previous and next node.
15
Which of these data structures is best for implementing LRU cache?
Answer & Solution
Answer: Option A
A combination of hash table and linked list allows O(1) access and update.
16
What is the space complexity of Depth First Search (DFS)?
Answer & Solution
Answer: Option B
DFS may go as deep as the number of nodes, requiring O(n) space.
17
Which operation in a binary heap has O(log n) time complexity?
Answer & Solution
Answer: Option A
Inserting into a binary heap takes O(log n) time to maintain heap property.
18
Which graph traversal algorithm uses recursion implicitly?
Answer & Solution
Answer: Option B
DFS uses recursion, either explicitly or implicitly via a stack.
19
What is the time complexity of inserting a node at the head of a linked list?
Answer & Solution
Answer: Option C
Insertion at the head of a linked list takes constant time.
20
Which sorting algorithm is best when the input list is almost sorted?
Answer & Solution
Answer: Option C
Insertion Sort performs efficiently on nearly sorted data.
21
Which data structure provides constant time lookup on average?
Answer & Solution
Answer: Option B
Hash Map provides O(1) average time complexity for lookup operations.
22
In a max-heap, the largest element is always at the:
Answer & Solution
Answer: Option C
The root of a max-heap contains the largest value.
23
Which data structure is best for implementing undo operations?
Answer & Solution
Answer: Option C
Undo operations are best implemented with stacks (LIFO).
24
What is the in-order traversal of a binary search tree?
Answer & Solution
Answer: Option B
In-order traversal of a BST visits nodes in ascending order: Left-Root-Right.
25
Which algorithm uses a divide-and-conquer strategy?
Answer & Solution
Answer: Option A
Quick Sort divides the array and recursively sorts subarrays.
26
Which algorithm is used to detect cycles in a graph?
Answer & Solution
Answer: Option B
DFS is commonly used to detect cycles in both directed and undirected graphs.
27
Which of the following is not a linear data structure?
Answer & Solution
Answer: Option B
Tree is a non-linear data structure.
28
Which of these is an application of stack?
Answer & Solution
Answer: Option A
Stacks are used in expression evaluation and syntax parsing.
29
Which data structure is used to implement a priority queue?
Answer & Solution
Answer: Option C
Heaps are commonly used to implement priority queues.
30
In a binary search tree (BST), what is the time complexity of searching for an element in the average case?
Answer & Solution
Answer: Option B
Average time complexity in a balanced BST is O(log n).