GATE DA 2024 Set 1 — Question 32

NAT+1 / -0EasyQueue Operations & ApplicationsStacks & QueuesProgramming, Data Structures & Algorithms

Programming, Data Structures & Algorithms → Stacks & Queues → Queue Operations & Applications

Last updated 5 September 2026

Question

The fundamental operations in a double-ended queue D are: insertFirst(e) - Insert a new element e at the beginning of D. insertLast(e) - Insert a new element e at the end of D. removeFirst() - Remove and return the first element of D. removeLast() - Remove and return the last element of D. In an empty double-ended queue, the following operations are performed: insertFirst(10) insertLast(32) a \leftarrowremoveFirst() insertLast(28) insertLast(17) a \leftarrowremoveFirst() a \leftarrow removeLast() The value of a is______.

Correct answer 17 to 17 Solution Let's trace the state of the double-ended queue D (front on left, rear on right): 1. Initially empty: [] 2. insertFirst(10) : D = [10] 3. insertLast(32) : D = [10, 32] 4. a \leftarrow removeFirst() : Removes 10. a = 10. D = [32] 5. insertLast(28) : D = [32, 28] 6. insertLast(17) : D = [32, 28, 17] 7. a \leftarrow removeFirst() : Removes 32. a = 32. D = [28, 17] 8. a \leftarrow removeLast() : Removes 17. a = 17. D = [28] The final value of a is 17. Turn this into a strength. Explore AI-powered practice and doubt support with Success Tracker.

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Correct answer 17 to 17 Solution Let's trace the state of the double-ended queue D (front on left, rear on right): 1. Initially empty: [] 2. insertFirst(10) : D = [10] 3. insertLast(32) : D = [10, 32] 4. a \leftarrow removeFirst() : Removes 10. a = 10. D = [32] 5. insertLast(28) : D = [32, 28] 6. insertLast(17) : D = [32, 28, 17] 7. a \leftarrow removeFirst() : Removes 32. a = 32. D = [28, 17] 8. a \leftarrow removeLast() : Removes 17. a = 17. D = [28] The final value of a is 17.

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