GATE 2024 DA – Question 32
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
Explanation
After the first two operations D is [10, 32]. removeFirst gives 10 and D is [32]. After the two insertLast operations D is [32, 28, 17]. The next removeFirst gives 32 and D is [28, 17]. The final removeLast returns 17, so $a = 17$.