Queue

: a list that insertion is done at one end, whereas deletion is performed at the other end

1. Abstract data type

• enqueue(X) : inserts element X at the end of the list
• dequeue(): deletes the element at the start of the list
• front(head) : index of the removal of existing element takes place
• rear(tail) : index of an element entered most recently

2. Implementations

• by Array
  • linear queue
  • circular queue
• by Linked-list

3. Use cases

• job scheduling : in the operating system which does not use priorities, jobs are processed in the order they enter the system
• Breath-First Search