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Double linked list.pptx
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- 2. Double Linked list •Single linked list= one-way list – List can be traversed in one direction only • Double linked list= Two-way list – List can be traversed in two directions • A two- way list is a linear collection of data elements called nodes where each node N is divided in to three parts – Data field contains the data of N – LLINK field contains the pointer to the preceding Node in the list – RLINK field contains the pointer to the next node in the list
- 3. Double Linked list –Data field contains the data of N – Rlink field contains the pointer to the next Node in the list – Llink field contains the pointer to the preceding node in the list Data Rlink Llink
- 4. Dr Zeinab Eid4 Double Linked List • Each node contain: • Element/data • link to the previous node • link to the next node llink rlink data 10 20 30 40 null head node
- 5. Node creation Algorithm: StructNode 1. Start 2. Declare int data, Node *llink, Node *rlink 3. exit Data null null
- 6. Node creation struct node { intdata; //data item in node struct node *llink,*rlink; // reference to leftt & right node }; data rlink llink
- 7. Insertion • In adouble linked list, a new node can be inserted: 1. At the first location 2. At the last location 3. At any position
- 8. Insertion at 1stlocation 1. head-> llink=temp 2. temp-> rlink=head 3. head=temp temp llink data rlink 20 head 10 null 30 null 5 null
- 9. Insertion in thefront 1. Set ptr=head 2. Create a new node temp //struct node *temp=(struct node*) malloc(sizeof(struct node)); 3. If(temp!= NULL) 4. Read ‘item’ to be inserted temp->data =item 5. head->llink=temp 6. temp-> rlink=head 7. head=temp 8. Else 9. Print “Unable to allocate memory”
- 10. Insertion at lastlocation 1. ptr->rlink=temp 2. temp->llink=ptr 20 head 10 null 30 null 35 null null Prev data next temp ptr
- 11. Insertion at lastlocation 1. Set ptr=head 2. Create a new node temp and read the element “item” to be inserted 3. temp->data= item 4. While(ptr-rlink!=null) 5. ptr=ptr->rlink 6 ptr->rlink=temp 7. temp->llink=ptr 20 head 10 null 30 null 35 null null Prev data next temp ptr
- 12. Insertion- after anelement key 20 head 10 null 30 null 25 Prev data next temp ptr Insert 25 after 20
- 13. Insertion- after anelement key 1. Read value key after which new node is to be inserted 2. Create temp and read element to be inserted 3. Set ptr=head 4. Repeat while( ptr->data!=key) 5. ptr=ptr->rlink 6. If(ptr-> data==key) 6. temp->rlink=ptr->rlink //7. set ptr1=ptr->rlink 7. ptr->rlink->llink= temp ptr1->llink=temp 8. temp->llink=ptr 9. ptr->rlink=temp
- 14. Deletion • In adouble linked list, an element can be deleted: 1. From the 1st location 2. From the last location 3. From intermediate location
- 15. Deletion- from 1stlocation • Delete node 10 1. head=head->rlink 2. head->llink= null 20 head 10 null null 30 null
- 16. Deletion- from lastlocation • Delete node 30 1. Set ptr=head 2. While(ptr->rlink!=null) 3. ptr=ptr->rlink 4. Set ptr1=ptr->llink 5. ptr1->rlink=null 6. free(ptr) 20 null head 10 null 30 null ptr ptr1
- 17. Deletion- from intermediatelocation • Delete node key=20 1. Set ptr=head 2. Repeat While (ptr-> data!=key)&& ptr->rlink!=null) 3. ptr=ptr->rlink 4. If(ptr->data=key) 5. ptr1=ptr->llink 6. ptr2=ptr->rlink 7. ptr1->rlink=ptr2 8. ptr2->llink=ptr1 9. free(ptr) 20 head 10 null 30 null ptr ptr1 ptr2
- 18. Circular double linkedlist • The advantages of both double linked list and circular linked list are incorporated into another type of list structure called circular double linked list 20 null 10 30 head
- 19. Circular double linkedlist • Here rlink of last node and llink of the first node points back to the head node. • Llink of head node contain the address of leftmost node • Rlink of head node contain the address of the rightmost node • Empty circular double linked list is represented as • Here both llink and rlink of head points to itself