GATE 2025 Data Structures MCQs
1. What data structure follows the Last In, First Out (LIFO) principle?
a) Stack
b) Queue
c) Linked List
d) Tree
Answer: a) Stack
2. Which data structure follows the First In, First Out (FIFO) principle?
a) Stack
b) Queue
c) Linked List
d) Tree
Answer: b) Queue
3. In a singly linked list, what is the reference of the last node?
a) NULL
b) First node
c) Middle node
d) Random node
Answer: a) NULL
4. Which data structure represents a hierarchical relationship between elements?
a) Stack
b) Queue
c) Linked List
d) Tree
Answer: d) Tree
5. What operation is performed on a stack to retrieve an element?
a) Push
b) Pop
c) Enqueue
d) Dequeue
Answer: b) Pop
6. What data structure is typically used to implement recursion?
a) Stack
b) Queue
c) Linked List
d) Tree
Answer: a) Stack
7. Which data structure uses pointers for sequential access?
a) Stack
b) Queue
c) Linked List
d) Tree
Answer: c) Linked List
8. In a binary tree, what is the maximum number of children a node can have?
a) 0
b) 1
c) 2
d) 3
Answer: c) 2
9. What operation is used to add an element to the top of a stack?
a) Push
b) Pop
c) Enqueue
d) Dequeue
Answer: a) Push
10. Which data structure is known for its constant time complexity for insertion, deletion, and search operations in average cases?
a) Stack
b) Queue
c) Linked List
d) Hash Table
Answer: d) Hash Table
11. What is the time complexity of accessing an element in a hash table?
a) O(1)
b) O(log n)
c) O(n)
d) O(n log n)
Answer: a) O(1)
12. Which data structure allows elements to be inserted from one end and removed from the other?
a) Stack
b) Queue
c) Linked List
d) Tree
Answer: b) Queue
13. What operation is used to remove an element from the front of a queue?
a) Push
b) Pop
c) Enqueue
d) Dequeue
Answer: d) Dequeue
14. Which data structure is used in breadth-first search (BFS) algorithm?
a) Stack
b) Queue
c) Linked List
d) Tree
Answer: b) Queue
15. In a linked list, what is the time complexity to insert an element at the beginning?
a) O(1)
b) O(log n)
c) O(n)
d) O(n log n)
Answer: a) O(1)
16. Which of the following is NOT a type of tree?
a) Binary Tree
b) AVL Tree
c) Trie
d) Circular List
Answer: d) Circular List
17. Which data structure is commonly used in depth-first search (DFS) algorithm?
a) Stack
b) Queue
c) Linked List
d) Tree
Answer: a) Stack
18. What data structure is used to implement a priority queue?
a) Stack
b) Queue
c) Linked List
d) Heap
Answer: d) Heap
19. In a binary search tree, what is the property of the left child with respect to its parent?
a) Greater than parent
b) Less than parent
c) Equal to parent
d) No relation with parent
Answer: b) Less than parent
20. Which of the following is NOT a valid collision resolution technique used in hash tables?
a) Chaining
b) Open Addressing
c) Quadratic Probing
d) Pre-order Traversal
Answer: d) Pre-order Traversal
21. What is the worst-case time complexity of searching for an element in a binary search tree?
a) O(1)
b) O(log n)
c) O(n)
d) O(n log n)
Answer: b) O(log n)
22. Which of the following is a valid tree traversal method?
a) Stack Traversal
b) Queue Traversal
c) Depth-first Traversal
d) Breadth-first Traversal
Answer: c) Depth-first Traversal
23. What data structure is typically used to implement a stack?
a) Linked List
b) Queue
c) Array
d) Tree
Answer: c) Array
24. Which of the following is a characteristic of a complete binary tree?
a) Every node has exactly two children
b) Every level is completely filled except possibly the last level
c) Every node has at most one child
d) The height of the tree is logarithmic
Answer: b) Every level is completely filled except possibly the last level
25. What operation is used to retrieve the top element of a stack without removing it?
a) Peek
b) Pop
c) Enqueue
d) Dequeue
Answer: a) Peek
26. Which data structure is used in the implementation of a hash table to handle collisions?
a) Stack
b) Queue
c) Linked List
d) Binary Tree
Answer: c) Linked List
27. In a linked list, what is the time complexity of deleting an element from the end?
a) O(1)
b) O(log n)
c) O(n)
d) O(n log n)
Answer: c) O(n)
28. What is the maximum number of children a node can have in an n-ary tree?
a) n
b) n - 1
c) 2n
d) Unlimited
Answer: a) n
29. What operation is used to add an element to the end of a queue?
a) Push
b) Pop
c) Enqueue
d) Dequeue
Answer: c) Enqueue
30. Which data structure is used to implement the undo functionality in text editors?
a) Stack
b) Queue
c) Linked List
d) Tree
Answer: a) Stack