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A first-in-first-out queue (FIFO queue) is an abstract data type. Each queue object holds a sequence of values. The type and operations are as follows.
Type Queue
| When an object of type Queue is created it starts out as an empty queue. Items can be added and removed by the operations below. |
isEmpty(q)
| Return true if queue q is empty, false if not. |
insertAtEnd(x, q)
| Add x to the end of q. |
removeFirst(q)
| Remove the first item from q and return it. If q is empty, return −1. |
peek(q)
| Return the first item in q without modifying q. If q is empty, return −1. |
Although a queue can contain any type of item, we will only look at queues whose items are integers for simplicity.
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