Updated April 17, 2023
Difference Between Deque vs Queue
The following article provides an outline for Deque vs Queue. Queue is a data structure which follows the FIFO (First In First Out) order in which the insertion of the elements takes place from the rear end, and the deletion takes place from the front end. It can be considered as the simple railway queue or the post office queue where the customers are added from the back and removed from the front one by one once the work is done. It is a simple linear data structure which is frequently used in the computer science.
Deque is a hybrid data structure that does not follow any FIFO or LIFO method to insert and delete elements. It is basically a hybrid data structure which uses the dynamic array for its implementation. In terms of the time and the utilization of resources, it is more efficient as compared to the Queue. Random access of elements is possible in the case of Deque data structure.
Head to Head Comparison Between Deque vs Queue (Infographics)
Below are the top 8 differences between Deque vs Queue:
Key Difference Between Deque vs Queue
Let us discuss some of the major key differences between Deque vs Queue:
- As the name indicates, Deque is a double-ended queue that is the implementation of the simple Queue. Still, the insertion and deletion of elements take place from both the ends. In contrast, Queue is a data structure where the insertion and deletion of elements take place only from the rear and front end, respectively.
- As the Deque allows the insertion and deletion of elements from both ends, it is basically more efficient than the Queue and allows the efficient usage of resources.
- Programmer can easily access the elements of the Deque using the Iterators, whereas it is not possible in the case of Queue as the programmer can access only the first and last element.
- Deque is a container template in which the requirements of the sequence can be satisfied using the random-access iterators, whereas Queue is an adaptor and not the container and provides a different and more specific interface to the user.
- As the elements can be inserted and deleted from both the ends in the Dequeue, so the operations for both are provided. To insert the element from the front, the push_front(x) operation is used. To insert the element from the back, the push_back(x) operation is used. In order to delete the element from the front in deque pop_front() is used, whereas to delete the element from the back, pop_back() is used, whereas in Queue, things are quite simpler as the insertion of elements takes place only from the rear end so push(x) operation is used and the removal of elements takes place from the front of the Queue, so pop() operation does it automatically.
- A queue is used in the scenarios where there is one cashier in the mall making all the bills, and all the customers make th.e Queue, where new customers can be added from the rear and removed from the front one by one once the billing is done whereas Deque is used in the scenarios where there are multiple customers and the cashiers. A cashier can entertain the customers from the end of the queue as well once they get free from the front customers.
Deque vs Queue Comparison Table
Let’s discuss the top comparison between Deque vs Queue:
| Sr. No | Deque | Queue |
| 1 | As the deque is a sequence container, so the insertion of elements takes place from both the ends, i.e. front and rear. | As the general behavior of Queue, insertion of the elements takes place from the one end, i.e. from the rear. |
| 2 | In deque, deletion of elements takes place from both the ends, i.e. front and rear. | In the normal queue, deletion of elements takes place from the front only. |
| 3 | As the deque has the ability to expand and contract from both the ends, it is implemented as dynamic arrays in the programs. | Talking about the implementation of Queue in a programming language, it is implemented as container adaptors. |
| 4 | Elements can easily be accessed in the deque using the iterators. | It is not possible to access the elements of the Queue using the iterators. |
| 5 | push_back(x) and push_front(x) functions are used in order to insert the elements in the Queue where push_back(x) will insert the element at the rear and push_Front(x) will insert the element at the front. | push(x) function is used in order to push the element in the Queue. Elements will be automatically inserted at the rear of the queue. |
| 6 | Similar to the insertion, for deletion of the elements in the deque, we have 2 functions, i.e. pop_back() and pop_front(), where pop_back() will delete the element from the deque from the back and pop_front() will remove the element from the queue from the front end. | In Queue, only one function is present in order to remove the element from the queue, i.e. pop(). It will automatically remove the element from the queue from the front end. |
| 7 | Deque is basically a hybrid data structure which provides the facility of both the stack and queue in a single data structure. | A queue is a single data structure providing the facility of only the Queue data structure. |
| 8 | Insertion and deletion of elements are more efficient as the resources are completely utilized in the case of the deque. | Insertion and deletion of elements are not much efficient in Queue as compared to deque. |
Conclusion
The above description clearly explains what the Queue and Deque are and the major differences between the two. A queue is a simple data structure where the insertion and deletion of elements take place from the one end, whereas Deque is a hybrid data structure serving the purpose of both the stack and queue and insertion and deletion of elements can take place from both the ends according to the requirements of the user.
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