Queue

Queue is a data structure that implements a FIFO (first-in first-out) ordering upon which the following operations are supported:

• add(object): add object at the end of the queue O(1)
• remove(): remove the object which at the beginning of the stack O(1)
• peek(): return object which is at the beginning of the stack O(1)

A queue can be used in BFS or to implement a cache.