Implementation of queue using singly and doubly linked list.
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The document discusses the implementation of a queue data structure using linked lists, detailing its definition, real-world applications, and advantages over arrays. It describes operations such as enqueue and dequeue and provides code examples for both singly and doubly linked list implementations. The summary highlights that queues operate on a first-in-first-out (FIFO) principle, with the doubly linked list offering efficiencies in traversal.
Implementation of queue using singly and doubly linked list.
- 1. Implementation of queue using linked list Submitted to Nemi Chandra Rathore HEAD OF THE DEPARTMENT Presented by Balmukund jha Mehul Mohan
- 2. CONTENTS • What is queue? • Real world examples of queue. • Applications of queue. • Queue implementation. • Advantage of linked list over array. • Operations on queue. • Implementation of queue using singly linked list . • Create queue implementation using singly linked list. • Implementation of queue using doubly linked list. • Create queue implementation using doubly linked list. • Time complexity . • Summary.
- 3. WHAT IS QUEUE? • Queue is a linear data structure. • It is used for temporary storage of data values. • A new element is added at one end called rear end . • The existing elements deleted from the other end called front end. • First in first out property.
- 4. Real world example of queue At bank counter. People on an escalator. At ATM machine. In one-way road.
- 6. People on an escalator.
- 7. Queue at ATM
- 9. Application of queue • Queues are widely used as waiting lists for a single shared resource like printer, disk, cpu. • Queues are used to transfer data asynchronously between two processes , e.g., file IO, sockets. • Queue are used as buffers on MP3 players and portable CD players , iPod playlist. • Queues are used in playlist for jukebox to add songs to the end , play from the front of the list.
- 10. Queue implementation Implementation *array based (linear or circular) *pointer based : linked list
- 11. ADVANTAGE OF LINKED LIST OVER ARRAY • Linked list provides two advantages over array *Dynamic memory allocation. *Ease of insertion and deletion.
- 12. THERE ARE TWO OPERATIONS ON QUEUE • ENQUEUE(INSERTION AT REAR) • DEQUEUE(DELETION FROM FRONT)
- 13. ENQUEUE Placing an item in a queue is called “insertion or enqueue”, which is done at the end of the queue called “rear”.
- 14. DEQUEUE Removing an item from a queue is called “deletion or dequeue”, which is done at the other end of the queue called “front”.
- 15. IMPLEMENTATION OF QUEUE USING SINGlY LINKED LIST • Create queue implementation using linked list struct queue { int data ; struct queue *next; } data next
- 16. Create queue implementation using singly linked list struct queue *front = NULL; struct queue *rear = NULL; NULL NULL front rear
- 17. Enqueue If there is no node present in the queue enqueue(ptrf, ptrr) { if(ptrf==NULL) { ptrf=newnode; ptrr=newnode; newnode->next = NULL; } } FRONT REAR newnode
- 18. Enqueue • If there is one node and multiple node in the queue ptrr->next = newnode; newnode->next = NULL; ptrr = newnode; front rear New node
- 19. After insertion of a node in the queue • If there is one node and multiple node in the queue newnode
- 20. Dequeue • If there is no node in the queue. • Message should be prompted to the user. Dequeue(ptrf, ptrr) { if(ptrf==NULL) { printf("n there is no data present in the queue"); } } front rear
- 21. Continue… • If there is one node available in the queue. • temp=ptrf if(temp->next ==NULL) { ptrf = NULL; ptrr =NULL; free(temp); } temp front rear
- 22. Continue… • If there are multiple node in the queue. • temp=ptrf ptrf= temp->next; free(temp) front rear temp x y
- 23. After deletion . y front rear
- 24. IMPLEMENTATION OF QUEUE USING DOUBLY LINKED LIST • Create queue implementation using doubly linked list Struct queue { int data ; struct queue *next; struct queue *prev; } prev data next
- 25. Create queue implementation using doubly linked list struct queue *front = NULL; struct queue *rear = NULL; NULL NULL front rear
- 26. Enqueue If there is no node in the linked list. We need to change the front and rear pointer. if(ptrf==NULL) { ptrf = newnode; ptrr = newnode; newnode->next = NULL; newnode->prev = NULL; } front rear
- 27. Continue… • If there is one or multiple node in the queue. (ptrr)->next= newnode; newnode->prev = ptrr; newnode->next = NULL; ptrr = newnode; front rear New node
- 28. After insertion… • v New node front rear
- 29. Dequeue • If there is no node in the queue. • We should prompt message . if(ptrf==NULL) { printf("n there is no data present in the queue"); }
- 30. Continue… • If there is one node in the queue. if(ptrf->next==NULL) { ptrf =NULL ptrr =NULL free(temp) } temp Ptrf=temp front rear
- 31. Continue… • After deleting front rear
- 32. Continue… • If there are multiple node in the queue. temp = ptrf; (temp->next)->prev = NULL; ptrf = temp->next; free(temp); temp Temp = ptrf
- 33. After deleting • -> front rear
- 34. Time complexity Singly linked list Doubly linked list Enqueue(O(1)) Enqueue(O(1)) Dequeue(O(1)) Dequeue(O(1)) Traverse(O(n)) Traverse(O(n)) Travresal is not an easy task Traversal is easy
- 35. summary • Queue is a linear data structure in which insertion is performed from rear and deletion is performed from front end . • A queue is a FIFO based data structure. • Doubly linked list is more efficient to implement a queue because of easy traversal.
- 36. THANK YOU !