Introduction

To Queue Or Not To Queue

• ordered collection of items where the addition of new items happens at one end and the removal of existing items occurs at the other end
• a linear collection of elements that are maintained in a sequence and can be modified by the addition of elements at one end of the sequence (enqueue operation) and the removal of elements from the other end (dequeue operation)
• as an element enters the queue it starts at the rear and makes its way toward the front, waiting until that time when it is the next element to be removed

• the name "queue" for this type of structure comes from the analogy to people lining up in real life to wait for goods or services
• the ordering principle FIFO, or first-in first-out, or first-come first-served

• as an abstract data type, stacks can be implemented using arrays or singly linked lists

Elements

Rear (Back)

• the end
• the most recently added items in the queue must wait at the end of the collection

Front

• the opposite of the end
• the item that has been in the collection the longest is at the front

Types

Circular Queue