The fundamental operations in a double-ended queue D are: insertFirst(e) –…
2024
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 ←removeFirst()
insertLast(28)
insertLast(17)
a ←removeFirst()
a ← removeLast()
The value of a is ______.
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Correct answer: 17
Final answer: 17
Work through the operations step by step (deque shown as [front ... back]):
Start: []
insertFirst(10) → [10]
insertLast(32) → [10, 32]
a ← removeFirst() removes 10, so a = 10; deque → [32]
insertLast(28) → [32, 28]
insertLast(17) → [32, 28, 17]
a ← removeFirst() removes 32, so a = 32; deque → [28, 17]
a ← removeLast() removes 17, so a = 17; deque → [28]
Therefore the final value of a is 17.