The numbers 3, 2, 5, 7 are enqueued in a queue in that order, then three numbers are dequeued, and finally 3, 7, 9, 4 are enqueued in that order. What is the first number in the queue the next number to be dequeued)?
A) 3
B) 7
C) 9
D) 4

Question

Quizplus · Accepted Answer

The queue is initially: 3 -> 2 -> 5 -> 7
After dequeuing three numbers, the queue becomes: 7 -> null
Then, 3, 7, 9, 4 are enqueued in that order, making the queue: 7 -> 3 -> 7 -> 9 -> 4
The next number to be dequeued is the first number in the queue, which is 7.

The Numbers 3, 2, 5, 7 Are Enqueued in a Queue