Data Structures Challenge 2 Solutions
Question 1​
Which of the following is not a linear data structure?
Options:
A) Array
B) Stack
C) Queue
D) Graph
Answer: D) Graph
Explanation: A graph is a non-linear data structure where elements (nodes) are connected by edges, allowing for more complex relationships compared to linear structures like arrays, stacks, and queues.
Question 2​
In which data structure do elements follow LIFO order?
Options:
A) Queue
B) Stack
C) Array
D) Linked List
Answer: B) Stack
Explanation: A stack operates on a Last In, First Out (LIFO) principle, meaning the most recently added element is the first to be removed.
Question 3​
Which of the following is a valid operation on a queue?
Options:
A) Push
B) Pop
C) Enqueue
D) Insert
Answer: C) Enqueue
Explanation: The operation to add an element to the end of a queue is called enqueue.
Question 4​
The minimum number of stacks needed to implement a queue is:
Options:
A) 1
B) 2
C) 3
D) 4
Answer: B) 2
Explanation: To effectively implement a queue using stacks, at least two stacks are required to handle the enqueue and dequeue operations.
Question 5​
Which of the following data structures is used to implement recursion?
Options:
A) Queue
B) Array
C) Stack
D) Linked List
Answer: C) Stack
Explanation: Recursion relies on a stack data structure to manage function calls, where each call is pushed onto the stack until it completes.
Question 6​
What is the main advantage of using a linked list over an array?
Options:
A) Faster access time
B) Dynamic size
C) Better memory utilization
D) Simplicity
Answer: B) Dynamic size
Explanation: Linked lists can grow or shrink in size dynamically, while arrays have a fixed size.
Question 7​
Which of the following is not a type of linked list?
Options:
A) Singly linked list
B) Doubly linked list
C) Circular linked list
D) Quadruple linked list
Answer: D) Quadruple linked list
Explanation: Quadruple linked lists are not standard; the common types are singly, doubly, and circular linked lists.
Question 8​
What is the height of a balanced binary tree with n nodes?
Options:
A) O(1)
B) O(log n)
C) O(n)
D) O(n log n)
Answer: B) O(log n)
Explanation: In a balanced binary tree, the height is logarithmic relative to the number of nodes, allowing for efficient search operations.
Question 9​
Which traversal technique is used to visit all nodes in a binary tree?
Options:
A) In-order
B) Pre-order
C) Post-order
D) All of the above
Answer: D) All of the above
Explanation: In-order, pre-order, and post-order traversals can all be used to visit nodes in a binary tree, each yielding different ordering of visits.
Question 10​
What is the main characteristic of a binary search tree?
Options:
A) All nodes have two children
B) Left subtree has lesser values, right subtree has greater values
C) Balanced height
D) None of the above
Answer: B) Left subtree has lesser values, right subtree has greater values
Explanation: This characteristic allows for efficient searching, insertion, and deletion in binary search trees.
Question 11​
What data structure is used for implementing a priority queue?
Options:
A) Array
B) Linked List
C) Heap
D) Stack
Answer: C) Heap
Explanation: A priority queue is typically implemented using a heap, which allows for efficient retrieval of the highest (or lowest) priority element.
Question 12​
What is the time complexity of accessing an element in a hash table?
Options:
A) O(1)
B) O(log n)
C) O(n)
D) O(n log n)
Answer: A) O(1)
Explanation: Accessing an element in a hash table is generally O(1) on average, thanks to direct indexing based on the hash value.
Question 13​
Which of the following sorting algorithms is not based on comparison?
Options:
A) Quick Sort
B) Merge Sort
C) Heap Sort
D) Counting Sort
Answer: D) Counting Sort
Explanation: Counting Sort is a non-comparison-based sorting algorithm that works by counting the occurrences of each distinct element.
Question 14​
Which data structure can be used to detect a cycle in a graph?
Options:
A) Queue
B) Stack
C) Array
D) Hash Table
Answer: B) Stack
Explanation: A stack can be used in depth-first search (DFS) to detect cycles in a graph by keeping track of visited nodes.
Question 15​
Which of the following is a disadvantage of a linked list?
Options:
A) Dynamic size
B) No random access
C) Easy insertion and deletion
D) Requires more memory
Answer: B) No random access
Explanation: Linked lists do not allow for random access like arrays do; you must traverse the list to access elements.
Question 16​
What is a common use of a hash table?
Options:
A) Storing ordered data
B) Implementing stacks
C) Implementing dictionaries
D) Creating binary trees
Answer: C) Implementing dictionaries
Explanation: Hash tables are often used to implement dictionaries because they provide efficient key-value pair storage and retrieval.
Question 17​
What is the average time complexity for insertion in a balanced binary search tree?
Options:
A) O(1)
B) O(log n)
C) O(n)
D) O(n log n)
Answer: B) O(log n)
Explanation: In a balanced binary search tree, insertion is performed in logarithmic time, making it efficient for dynamic data sets.
Question 18​
What is the space complexity of a linked list?
Options:
A) O(1)
B) O(n)
C) O(n log n)
D) O(log n)
Answer: B) O(n)
Explanation: A linked list requires space for each node, leading to linear space complexity proportional to the number of elements.
Question 19​
Which of the following is a property of a min-heap?
Options:
A) The parent node is always greater than its child nodes
B) The parent node is always equal to its child nodes
C) The parent node is always less than or equal to its child nodes
D) There is no specific order
Answer: C) The parent node is always less than or equal to its child nodes
Explanation: In a min-heap, the smallest element is always at the root, and each parent node is less than or equal to its children.
Question 20​
Which of the following traversal methods will give you nodes of a binary tree in ascending order?
Options:
A) Pre-order
B) Post-order
C) In-order
D) Level-order
Answer: C) In-order
Explanation: In-order traversal of a binary search tree visits nodes in ascending order.
Question 21​
Which data structure uses a "first-in, first-out" (FIFO) method?
Options:
A) Stack
B) Queue
C) Linked List
D) Tree
Answer: B) Queue
Explanation: A queue operates on a first-in, first-out basis, meaning the first element added is the first to be removed.
Question 22​
In a binary tree, what is the maximum number of nodes at level l?
Options:
A) 2^l
B) 2^(l-1)
C) l^2
D) l
Answer: A) 2^l
Explanation: The maximum number of nodes at level l in a binary tree is 2^l, where the root is considered at level 0.
Question 23​
What is the time complexity of searching for an element in a balanced binary search tree?
Options:
A) O(1)
B) O(log n)
C) O(n)
D) O(n log n)
Answer: B) O(log n)
Explanation: Searching in a balanced binary search tree is efficient, with a time complexity of O(log n).
Question 24​
Which data structure is suitable for implementing a recursive algorithm?
Options:
A) Queue
B) Stack
C) Array
D) Hash Table
Answer: B) Stack
Explanation: A stack is ideal for implementing recursive algorithms, as it can keep track of function calls and local variables.
Question 25​
What is the primary benefit of using a doubly linked list over a singly linked list?
Options:
A) More memory-efficient
B) Faster traversal
C) Easy insertion and deletion at both ends
D) No additional pointers needed
Answer: C) Easy insertion and deletion at both ends
Explanation: A doubly linked list allows for easy traversal in both directions, making insertion and deletion at both ends more efficient.