Data Structures MCQs

This comprehensive set of MCQs on Data Structures is designed to cover all essential topics necessary for understanding the fundamental concepts and applications of data organization and management. Focused on key subjects such as arrays, linked lists, stacks, queues, trees, and graphs, these MCQs aim to help students and professionals build a strong foundation in data structures, which are crucial for efficient algorithm design and problem-solving in computer science.

Who should practice Data Structure MCQs?

• Students pursuing degrees in computer science, software engineering, or information technology who need to grasp the principles of data organization.
• Individuals preparing for exams or certifications that include data structures as part of their curriculum.
• Anyone aiming to strengthen their knowledge of various data structures and their applications in programming and algorithm design.
• Candidates looking to improve their problem-solving skills and critical thinking related to data management and processing.
• Professionals seeking to enhance their skills in software development and system design through effective use of data structures.
• Suitable for all students eager to develop their technical skills and gain confidence in applying data structures to solve complex computational problems.

1. What is the time complexity to access an element in an array?

A. O(1)
B. O(log n)
C. O(n)
D. O(n^2)

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2. Which of the following operations is not possible on an array?

A. Insertion
B. Deletion
C. Searching
D. Sorting

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3. What is the time complexity to search for an element in a sorted array using binary search?

A. O(1)
B. O(log n)
C. O(n)
D. O(n log n)

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4. Which of the following data structures can be used to implement a linked list?

A. Arrays
B. Stacks
C. Queues
D. Pointers

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5. In a singly linked list, which pointer field of the last node points to NULL?

A. Next
B. Previous
C. Front
D. Rear

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6. Which of the following operations is typically not efficient in a singly linked list?

A. Insertion at the beginning
B. Deletion from the end
C. Accessing elements by index
D. Traversing the list from beginning to end

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7. Which data structure uses LIFO (Last In First Out) order?

A. Queue
B. Stack
C. Linked list
D. Heap

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8. Which operation is not typically performed on a stack?

A. Push
B. Pop
C. Insertion
D. Peek

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9. Which of the following is an application of a queue data structure?

A. Recursion
B. DepthFirst Search
C. BreadthFirst Search
D. Binary Search

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10. What is the maximum number of children that a node can have in a binary tree?

A. 2
B. 1
C. 3
D. Unlimited

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11. Which traversal technique visits the root node before its descendants?

A. Preorder
B. Inorder
C. Postorder
D. Level order

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12. What is the height of a tree with a single node?

A. 0
B. 1
C. Undefined
D. 2

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13. Which data structure is most commonly used to represent graphs?

A. Arrays
B. Linked lists
C. Adjacency matrix
D. Stack

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14. Which algorithm is used to find the shortest path in a weighted graph?

A. DepthFirst Search (DFS)
B. BreadthFirst Search (BFS)
C. Dijkstra’s algorithm
D. Prim’s algorithm

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15. Which sorting algorithm has the worstcase time complexity of O(n^2)?

A. Merge sort
B. Quick sort
C. Bubble sort
D. Insertion sort

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16. Which searching algorithm is not suitable for large datasets?

A. Linear search
B. Binary search
C. DepthFirst Search (DFS)
D. BreadthFirst Search (BFS)

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17. What is the average time complexity for inserting an element into a hash table with separate chaining?

A. O(1)
B. O(log n)
C. O(n)
D. O(n log n)

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18. Which collision resolution technique uses an array of linked lists?

A. Linear probing
B. Quadratic probing
C. Separate chaining
D. Double hashing

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19. Which data structure is best suited for implementing a dictionary with fast search, insert, and delete operations?

A. Linked list
B. Stack
C. Binary tree
D. Hash table

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20. Which of the following data structures is nonlinear?

A. Array
B. Linked list
C. Queue
D. Tree

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21. Which algorithm is used to find the minimum spanning tree in a weighted graph?

A. Dijkstra’s algorithm
B. BreadthFirst Search (BFS)
C. DepthFirst Search (DFS)
D. Prim’s algorithm

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22. What is the time complexity of Prim’s algorithm when implemented with a binary heap?

A. O(V log E)
B. O(E log V)
C. O(V^2)
D. O(E^2)

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23. Which traversal technique visits the root node between its left and right subtrees?

A. Preorder
B. Inorder
C. Postorder
D. Level order

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24. What is the minimum number of nodes in a binary tree of height 4?

A. 4
B. 15
C. 16
D. 31

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25. Which sorting algorithm is stable and has a worstcase time complexity of O(n log n)?

A. Bubble sort
B. Insertion sort
C. Quick sort
D. Merge sort

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26. Which searching algorithm requires the data to be sorted?

A. Linear search
B. Binary search
C. DepthFirst Search (DFS)
D. BreadthFirst Search (BFS)

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27. Which collision resolution technique rehashes with a different hash function when a collision occurs?

A. Linear probing
B. Quadratic probing
C. Separate chaining
D. Double hashing

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28. What is the load factor of a hash table?

A. The ratio of filled slots to total slots
B. The number of collisions
C. The time complexity of hash functions
D. The number of hash functions used

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29. Which data structure is used in recursion?

A. Stack
B. Queue
C. Heap
D. Array

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30. Which data structure is typically used to implement a LIFO queue?

A. Stack
B. Queue
C. Linked list
D. Heap

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31. Which data structure is suitable for efficiently finding the nearest neighbors in multidimensional space?

A. Binary tree
B. KDtree
C. AVL tree
D. Trie

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32. Which data structure is used for creating Huffman codes in data compression?

A. Binary search tree
B. AVL tree
C. Trie
D. Minheap

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33. Which operation typically has the highest time complexity in a selfbalancing binary search tree?

A. Insertion
B. Deletion
C. Searching
D. Rotation

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34. Which data structure is best suited for implementing a priority queue?

A. Queue
B. Stack
C. Heap
D. Linked list

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35. Which data structure can efficiently support range queries and updates?

A. AVL tree
B. Segment tree
C. Btree
D. Radix tree

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36. Which data structure is used for representing hierarchical data with a dynamic number of children per node?

A. Binary tree
B. Btree
C. Trie
D. Nary tree

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37. Which data structure is commonly used for implementing the Undo operation in text editors?

A. Stack
B. Queue
C. Linked list
D. Hash table

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38. Which data structure is used for implementing caching mechanisms?

A. Linked list
B. Hash table
C. Btree
D. AVL tree

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39. Which data structure would you use to efficiently determine the frequency of elements in a dataset?

A. Stack
B. Queue
C. Hash table
D. Heap

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40. Which data structure is used in the implementation of LRU (Least Recently Used) cache eviction policies?

A. Queue
B. Stack
C. Linked list
D. Hash table

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41. Which data structure is used in the A* algorithm for pathfinding?

A. Queue
B. Stack
C. Priority queue
D. Linked list

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42. Which data structure is best suited for storing the adjacency list representation of a graph?

A. Linked list
B. Stack
C. Queue
D. Hash table

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43. Which data structure would you use to implement the “undo” feature in a graphics editor?

A. Stack
B. Queue
C. Linked list
D. Array

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44. Which data structure is used in the implementation of a web browser’s history feature?

A. Stack
B. Queue
C. Linked list
D. Hash table

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45. Which data structure is essential for implementing DepthFirst Search (DFS) in a graph traversal?

A. Stack
B. Queue
C. Linked list
D. Binary search tree

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46. Which data structure is commonly used to efficiently find the median of a dataset?

A. Queue
B. Stack
C. Binary search tree
D. Heap

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47. Which data structure is used to implement a trie (prefix tree)?

A. Linked list
B. Queue
C. Hash table
D. Array

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48. Which data structure is used to efficiently merge two sorted arrays into a single sorted array?

A. Stack
B. Queue
C. Heap
D. Linked list

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49. Which data structure is typically used in the implementation of Kruskal’s algorithm for finding the minimum spanning tree?

A. Stack
B. Queue
C. Disjointset (UnionFind)
D. Hash table

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50. Which data structure is used in the implementation of dynamic programming algorithms for optimal substructure?

A. Queue
B. Stack
C. Linked list
D. Array

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51. Which data structure is commonly used in the implementation of a priority scheduling algorithm in operating systems?

A. Stack
B. Queue
C. Binary search tree
D. Heap

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52. Which data structure is essential for implementing the Kruskal’s algorithm for finding the minimum spanning tree in a graph?

A. Stack
B. Queue
C. Disjointset (UnionFind)
D. Linked list

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53. Which data structure is used to efficiently implement a set of integers with operations like insertion, deletion, and finding the minimum or maximum element?

A. Queue
B. Stack
C. AVL tree
D. Heap

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54. Which data structure is commonly used to implement a priority queue with operations like insertion and extraction of the highest priority element?

A. Queue
B. Stack
C. Linked list
D. Heap

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55. Which data structure is used to efficiently support range queries and updates in an arraylike structure?

A. Segment tree
B. AVL tree
C. Trie
D. Radix tree

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56. Which data structure is used to represent the relationship between parent and child nodes in hierarchical data structures?

A. Queue
B. Stack
C. Linked list
D. Pointerbased structure

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57. Which data structure is typically used to implement a depthfirst search (DFS) algorithm in a graph traversal?

A. Stack
B. Queue
C. Linked list
D. Binary search tree

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58. Which data structure is commonly used to efficiently compute the union and intersection of sets?
A. Queue
B. Stack
C. Hash table
D. Linked list

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59. Which data structure is essential for implementing a backtracking algorithm to solve constraint satisfaction problems?

A. Stack
B. Queue
C. Binary search tree
D. Heap

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60. Which data structure is used in the implementation of a breadthfirst search (BFS) algorithm for graph traversal?

A. Stack
B. Queue
C. Linked list
D. Binary search tree

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61. What is a data structure?

A) A method to analyze data
B) A way of organizing and storing data
C) A programming language
D) A type of algorithm

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62. Which of the following is a linear data structure?

A) Tree
B) Graph
C) Stack
D) Hash Table

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63. What is the main purpose of a stack?

A) To store data in a sorted manner
B) To allow random access of elements
C) To manage function calls and local variables
D) To maintain a list of items

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64. In a queue, elements are added at the:

A) Front
B) Back
C) Middle
D) Both front and back

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65. Which of the following data structures allows insertion and deletion at both ends?

A) Stack
B) Queue
C) Deque
D) Linked List

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66. Which traversal method is used for binary trees?

A) Linear
B) In-order
C) Random
D) Sequential

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67. What is the time complexity of accessing an element in an array?

A) O(n)
B) O(log n)
C) O(1)
D) O(n^2)

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68. What type of data structure is used to implement recursion?

A) Array
B) Stack
C) Queue
D) Linked List

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69. Which of the following is a non-linear data structure?

A) Array
B) Linked List
C) Stack
D) Graph

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70. In a doubly linked list, each node contains:

A) Data only
B) Data and one pointer
C) Data and two pointers
D) Data and three pointers

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71. Which of the following operations can be performed on a binary search tree (BST)?

A) Insert
B) Delete
C) Search
D) All of the above

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72. What is the worst-case time complexity for searching an element in a balanced binary search tree?

A) O(n)
B) O(log n)
C) O(n log n)
D) O(1)

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73. What is a hash table used for?

A) To store sorted data
B) To allow quick data retrieval
C) To manage recursive calls
D) To implement a priority queue

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74. In a circular linked list, the last node points to:

A) The first node
B) The middle node
C) Null
D) The previous node

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75. Which of the following sorting algorithms has the best average-case time complexity?

A) Bubble Sort
B) Selection Sort
C) Merge Sort
D) Insertion Sort

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76. Which data structure is used to implement a priority queue?

A) Array
B) Stack
C) Binary Heap
D) Linked List

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77. What does BFS stand for in graph theory?

A) Best-First Search
B) Breadth-First Search
C) Binary First Search
D) Backtracking First Search

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78. What is the primary disadvantage of a linked list compared to an array?

A) Requires more memory
B) Difficult to implement
C) Does not allow dynamic resizing
D) Cannot store elements of different types

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79. Which of the following is NOT a type of binary tree?

A) Full Binary Tree
B) Complete Binary Tree
C) Balanced Binary Tree
D) Quad Tree

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80. In a max heap, the value of each node is:

A) Less than its children
B) Greater than its children
C) Equal to its children
D) Random

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81. Which data structure uses LIFO (Last In First Out) principle?

A) Queue
B) Stack
C) Linked List
D) Array

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82. Which of the following operations can be performed in constant time O(1) on a hash table?

A) Search
B) Insert
C) Delete
D) All of the above

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83. In which data structure are elements added and removed from the same end?

A) Queue
B) Stack
C) Linked List
D) Array

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84. What is the height of a complete binary tree with n nodes?

A) log n
B) n
C) log(n + 1)
D) n/2

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85. What is a characteristic of a binary search tree (BST)?

A) All nodes have two children
B) The left child is greater than the parent
C) The right child is less than the parent
D) The left child is less than the parent

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86. In a depth-first search (DFS), which data structure is primarily used?

A) Queue
B) Stack
C) Array
D) Linked List

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87. Which algorithm is used to find the shortest path in a graph?

A) Depth-First Search
B) Breadth-First Search
C) Dijkstra’s Algorithm
D) Prim’s Algorithm

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88. What is the primary use of a trie data structure?

A) Storing sorted data
B) Implementing priority queues
C) Storing strings for fast retrieval
D) Managing memory allocation

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89. Which of the following statements is true about a stack?

A) It allows random access of elements.
B) It is a linear data structure.
C) The first element added is the first to be removed.
D) It can only store integers.

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90. What is the worst-case time complexity of bubble sort?

A) O(n)
B) O(n log n)
C) O(n^2)
D) O(log n)

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91. Which data structure is best suited for implementing recursion?

A) Queue
B) Stack
C) Array
D) Linked List

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92. What type of search algorithm is used in a binary search tree?

A) Linear Search
B) Binary Search
C) Depth-First Search
D) Hash Search

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93. Which of the following data structures can be used to implement a recursion stack?

A) Array
B) Stack
C) Queue
D) Tree

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94. In a graph, what does the term “vertex” refer to?

A) An edge connecting two nodes
B) A point where edges meet
C) The total number of nodes
D) The weight of an edge

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95. What is the time complexity of inserting an element at the beginning of a singly linked list?

A) O(1)
B) O(n)
C) O(log n)
D) O(n^2)

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96. In a hash table, what is a collision?

A) When two different keys map to the same index
B) When a key is deleted
C) When the hash table is full
D) When two keys are equal

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97. Which data structure is typically used for breadth-first search (BFS)?

A) Stack
B) Queue
C) Array
D) Linked List

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98. What is the time complexity of the merge sort algorithm?

A) O(n)
B) O(n log n)
C) O(n^2)
D) O(log n)

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99. In a circular queue, the front and rear pointers:

A) Always point to the same element
B) Wrap around when they reach the end of the queue
C) Cannot be moved
D) Must be equal

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100. Which of the following operations can be performed on a linked list?

A) Insert at the beginning
B) Delete from the end
C) Traverse the list
D) All of the above

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101. What is a common application of a stack?

A) Memory management
B) Undo mechanism in software
C) Task scheduling
D) Data caching

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102. Which of the following is a disadvantage of a linked list?

A) Dynamic size
B) Memory overhead for pointers
C) Easy insertion and deletion
D) None of the above

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103. Which of the following is NOT a characteristic of a queue?

A) FIFO (First In First Out)
B) Last In First Out
C) Enqueue operation
D) Dequeue operation

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104. What is the average-case time complexity of quicksort?

A) O(n)
B) O(n log n)
C) O(n^2)
D) O(log n)

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105. In a binary tree, what is the maximum number of nodes at level ‘l’?

A) l
B) 2^l
C) 2^(l-1)
D) 2^l – 1

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106. What is the primary purpose of a sentinel node in linked lists?

A) To increase memory usage
B) To simplify boundary conditions
C) To improve access speed
D) To store additional data

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107. Which of the following sorting algorithms is NOT stable?

A) Merge Sort
B) Quick Sort
C) Bubble Sort
D) Insertion Sort

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108. What is the primary disadvantage of using an array?

A) Fixed size
B) Random access
C) Fast access
D) Easy implementation

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109. Which data structure is best for implementing an adjacency list for a graph?

A) Array
B) Linked List
C) Hash Table
D) All of the above

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110. In a binary search tree, the left child of a node contains:

A) Values greater than the node
B) Values less than the node
C) Random values
D) The same value as the node

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111. Which of the following is used to represent hierarchical data?

A) Array
B) Tree
C) Stack
D) Queue

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112. Which data structure can be used to implement a backtracking algorithm?

A) Stack
B) Queue
C) Array
D) Linked List

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113. What is the main characteristic of a binary tree?

A) Each node can have at most two children
B) Each node can have multiple children
C) It is always balanced
D) It is always complete

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114. In which of the following data structures can duplicate values be stored?

A) Set
B) Queue
C) Stack
D) All of the above

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115. Which algorithm is used to find the minimum spanning tree in a graph?

A) Dijkstra’s Algorithm
B) Prim’s Algorithm
C) Depth-First Search
D) Bellman-Ford Algorithm

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116. Which data structure uses a priority value to determine the order of processing?

A) Stack
B) Queue
C) Priority Queue
D) Hash Table

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117. What is the main advantage of using a hash table?

A) Simple implementation
B) Fast access time
C) Easy to manage memory
D) No collisions

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118. In which scenario is a binary search tree preferred over an array?

A) When memory usage is a concern
B) When frequent insertions and deletions are needed
C) When random access is required
D) When data is static

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119. Which of the following data structures is best suited for implementing a “next” function in a browser?

A) Stack
B) Queue
C) Linked List
D) Array

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120. Which algorithm is NOT used for sorting?

A) Merge Sort
B) Insertion Sort
C) Depth-First Search
D) Quick Sort

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