DSL Unit 4 (Linked list) (PPT)SE3rd sem sppu.pptx
- 1. LINKED LIST
- 2. INTRODUCTION The linked list is a very effective and efficient dynamic data structure Data items can be stored anywhere in memory in a scattered manner To maintain the specific sequence of these data items we need to maintain link(s) with successor (and/ or predecessor) It is called as a linked list
- 3. INTRODUCTION A linked list is an ordered collection of data in whi each element contains minimum two values, da and link(s) to its successor (and/ or predecessor) The list with one link field using which every eleme is associated to either its predecessor or successor called as singly linked list In a linked list, before adding any element to the li memory space for that node must be allocated A link is kept with each item to the next item in the li
- 4. Fig: 2 (a): A linked list of n elements Fig: 2 (b) : A linked list of weekdays
- 5. Each node of the linked list has minimum two elements : The data member(s) being stored in the list A pointer or link to the next element in the list The last node in the list contains a NULL (or -1) pointer to indicate that it is the end or tail of the list
- 6. Linked Organization Element can be placed anywhere in the memory Dynamic allocation (size need not be known in advance) i.e. space allocation as per need can be done during execution. As objects are not placed at fixed distance apart, random access to elements is not possible. Insertion and deletion of objects do not require any data shifting. Space efficient for large objects and large quantity with often insertions and deletions Each element in general is a collection of data and a link. At least one link field is must. Every element keeps address of its successor element in a link field.
- 7. Some more operations, which are based on above basic operations are: Searching a node Updating node. Printing the node or list. Counting length of the list. Reverse the list. Sort the list using pointer manipulation. Concatenate two lists. Merge two-sorted list into third sorted list
- 8. The Linked List ADT Data Structure of Node Insertion of a Node Linked List Traversal Non-Recursive Method Recursive Traversal Method
- 9. Types of Linked List Singly linked list Doubly linked list Circular linked list
- 10. Singly Linked List A linked list in which every node has one link field, to provide information about where the next node of list is, is called as singly linked list
- 11. Doubly linked list In doubly linked list, each node has two link fields to store information about who is the next and also about who is ahead of the node Hence each node has knowledge of its successor and also its predecessor. In doubly linked list, from every node the list can be traversed in both the directions.
- 12. Circular linked list For example, consider a singly linked list. Given a pointer A to a node in a linear list, we cannot reach any of the nodes that precede the node to which A is pointing. This disadvantage can be overcome by making a small change. This change is without any additional data structure. The link field of last node is set to NULL in linear list to mark end of list. This link field of last node can be set to point first node rather than NULL. Such a linked list is called a circular linked list. Although a linear linked list is a useful and popular data structure, it has some shortcomings.
- 14. class node { int data; // data node* next; // pointer to next public: node* create(); void display(node*); node* beg_del(node*); node* end_del(node*); node* mid_del(node*); node* beg_add(node*); node* end_add(node*); node* mid_add(node*); node* total(node*); };
- 15. node* node::create() { node* head,*p; head=NULL; cout<<"Enter the number of members"<<endl; cin>>n; for(i=0;i<n;i++) { if(head==NULL) { head=new node; cout<<"Enter the roll number and name of the member"<<endl; cin>>head->rno; cin>>head->name; head->next=NULL; p=head; } else { p->next=new node; p=p->next; cout<<"Enter the roll number and name of the member"<<endl; cin>>p->rno; cin>>p->name; p->next=NULL; }
- 16. void node::display(node *head) { for(p=head;p!=NULL;p=p->next) { cout<<"Roll No:"<<p->rno<<" "; cout<<"Name:"<<p- >name<<endl; } }
- 17. Inserting a new node Possible cases of InsertNode 1. Insert into an empty list 2. Insert in front 3. Insert at back 4. Insert in middle But, in fact, only need to handle two cases 1. Insert as the first node (Case 1 and Case 2) 2. Insert in the middle or at the end of the list (Case 3 and Case 4)
- 18. node* node::beg_add(node* head) { p=new node; cout<<"Enter the roll number and name of the member"<<endl; cin>>p->rno; cin>>p->name; p->next=NULL; p->next=head; head=p; return head; } node* node::end_add(node* head) { p=new node; cout<<"Enter the roll number and name of the member"<<endl; cin>>p->rno; cin>>p->name; p->next=NULL; for(q=head;q->next!=NULL;q=q->next); q->next=p; return head; }
- 19. node* node::mid_add(node* head) { p=new node; cout<<"Enter the roll number and name of the member"<<endl; cin>>p->rno; cin>>p->name; p->next=NULL; cout<<"Enter the value after which you want to insert the member"; cin>>y; for(q=head;q->rno==y && q!=NULL;q=q->next); if(q==NULL) { cout<<"Data not found"; } else { p->next=q->next; q->next=p; }
- 20. Deleting node Possible cases of InsertNode 1. Delete from front 2. Delete from back 3. Delete middle element
- 21. node* node::beg_del(node* head) { p=head; head=head->next; delete p; return head; } node* node::end_del(node* head) { for(p=head;p->next->next!=NULL;p=p->next); q=p->next; p->next=NULL; delete q; }
- 22. node* node::mid_del(node* head) { cout<<"Enter the roll number of the member which you want to delete"; cin>>y; if( head==NULL) { cout<<"linked list is empty"; return(head); } for(p=head;p->next->rno==y && p->next!=NULL;p=p->next) { p->next=p->next->next; delete p->next; } return head; }
- 23. Polynomial Manipulations A node will have 3 fields, which represent the coefficient and exponent of a term and a pointer to the next term
- 24. For instance, the polynomial, say A = 6x7 + 3x5 + 4x3 + 12 would be stored as :
- 25. Operations on Polynomials Polynomial evaluation Polynomial addition Multiplication of two polynomials Representation of sparse matrix using linked list Linked list implementation of the stack Generalized linked list
- 26. Garbage Collection : An Application Of Linked List Overflow : Sometimes new data node is to be inserted into data structure but there is no available space i.e. free-pool is empty. This situation is called overflow Underflow : This refers to situation where programmer wants to delete a node from empty list For good memory utilization, operating system periodically collects all the free blocks and inserts into free-pool Any technique that does this collection is called garbage collection
- 27. Summary There are two implementation of linked linear list; array and pointers There is a need is of such a data structure which can dynamically shrink and grow Hence the popular implementation us using pointers and dynamic memory management Singly linked lists are useful data structures, especially if you need to automatically allocate and de-allocate space in a list The basic operation are create list, transverse the list, insert and delete a node There are two variation of linked list singly and doubly linked list. Both linked list can be circular lists The linked could be with or without head node. Head node is used to store some information about the list, so that it can be accessed without traversing the same
- 28. Summary In doubly linked list, each node has two link fields to store information about who is the next and also about who is ahead of the node Hence each node has knowledge of its successor and also its predecessor. In doubly linked list, from every node the list can be traversed in both the directions. Information could be like total number of nodes in the list and similarly any other Linked list is the most popular data structure used. It has many application such as process queue, print queue, garbage collection etc
- 29. l Sequential organisation Provides static allocation, which means space allocation is done by compiler once cannot be changed during execution and size has to be known in advance. As individual objects are stored at fixed distance apart, we can access any element randomly. Insertion and deletion of objects in between the list requires a lot of data movement. Space inefficient for large objects and large quantity with often insertions and deletions Element need not know/store keep address of its successive element.