Introduction to Deque

A Deque (Double-Ended Queue) is a linear data structure that allows insertion and deletion of elements from both ends. Unlike a stack or a queue, where operations are restricted to one end, a deque provides flexibility to add or remove elements at the front as well as the rear.

• Deque can act as both Stack and Queue
• It is useful in many problems where we need to have a subset of all operations also like insert/remove at front and insert/remove at the end.
• It is typically implemented either using a doubly linked list or circular array.

Common Operations of Deque:

In order to make manipulations in a deque, there are certain operations provided to us.

1. insertFront(x) → Insert an element at the front end.
2. insertRear(x) → Insert an element at the rear end.
3. deleteFront() → Delete an element from the front end.
4. deleteRear() → Delete an element from the rear end.
5. getFront() → Retrieve (but don’t remove) the front element.
6. getRear() → Retrieve (but don’t remove) the rear element.
7. isEmpty() → Check if the deque is empty.
8. size() → Return the number of elements currently in the deque.

Code Example

30 10 20 
10 

Implementation of Deque:

Deque can be implemented in Different Ways :-

• Implementation of Deque Using Array
• Implementation of Deque Using LinkedList

Advantage of Deque: