What is the value of the postfix expression 9 3 / 2 ^ 1 + , where ^ means exponentiation?
Correct answer D. 10
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Data Structures MCQs
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A tree has 25 nodes. How many edges does it have?
Correct answer C. 24
What is the maximum number of nodes in a binary tree of height 3, where height is the number of edges on the longest root-to-leaf path?
Correct answer D. 15
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In a binary tree where the root is at level 0, what is the maximum number of nodes at level 4?
Correct answer A. 16
A queue is implemented with two stacks, where enqueue pushes onto stack S1 and dequeue pops from S2, refilling S2 from S1 only when S2 is empty. What is the amortised cost of each operation?
Correct answer A. O(1)
Which data structure is commonly used to implement a priority queue efficiently?
Correct answer C. Binary heap
What is a deque?
Correct answer B. A queue that allows insertion and deletion at both ends
A circular queue of capacity 5 (indices 0 to 4) starts empty with front = 0 and rear = −1. Five elements are enqueued, two are dequeued and one more is enqueued. What are front and rear now?
Correct answer D. front = 2, rear = 0
Why is a circular queue preferred over a simple linear array queue?
Correct answer D. It reuses array slots freed by dequeues, so space at the front is not wasted
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In a circular queue implemented with an array of size n, using front and rear indices with one slot always left empty, which condition means the queue is full?
Correct answer D. (rear + 1) % n == front
Which data structure is most suitable for checking whether the brackets in an expression such as {} are balanced?
Correct answer A. Stack
Which of the following is a non-linear data structure?
Correct answer B. Tree
Which statement best distinguishes a static data structure from a dynamic one?
Correct answer A. A static structure has a size fixed when it is created, while a dynamic one can grow or shrink at run time
What is the time complexity of accessing the element at a given index in an array?
Correct answer C. O(1)
If an algorithm takes 3n² + 5n + 20 steps for an input of size n, what is its Big-O complexity?
Correct answer D. O(n²)
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Which growth rate is the slowest for large values of n?
Correct answer C. O(log n)
What does the space complexity of an algorithm measure?
Correct answer A. How the memory it needs grows with the input size
Which notation gives an asymptotic lower bound on an algorithm’s running time?
Correct answer B. Big-Omega (Ω)
What is the time complexity of searching for a value in an unsorted array of n elements?
Correct answer D. O(n)
A two-dimensional array A of 4-byte integers is stored in row-major order starting at address 1000, with indices starting at 0. What is the address of A?
Correct answer C. 1260