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Operations on linked list
- 2. Organization of dataand theOrganization of data and the relationship among its members isrelationship among its members is called as data structurecalled as data structure Data Structure
- 4. Why we needLinked List? What are the problems with Arrays? Size is fixed Array Items are stored contiguously Insertions and deletion at particular position is complex Why Linked list ? Size is not fixed Data can be stored at any place Insertions and deletions are simple and faster
- 5. What are LinkedListsWhat are Linked Lists A linked list is a linear data structure. Nodes make up linked lists. Nodes are structures made up of data and a pointer to another node. Usually the pointer is called next.
- 6. A linkedlist consists of: ◦ A sequence of nodes 6 a b c d Each node contains a value and a link (pointer or reference) to some other node The last node contains a null link The list may (or may not) have a header myList
- 7. Linked List Types Singly Linked list Doubly linked lists Circular singly linked list Circular doubly linked lists
- 8. Each nodehas only one link part Each link part contains the address of the next node in the list Link part of the last node contains NULL value which signifies the end of the node
- 9. 10 1000 1000 2000 200015 NULL20 4000 Singly LinkedList Each node points the next node . It is a one way list. First
- 10. 10 15 20 CircularSingly Linked List Last node contains the address of the first node First
- 11. Doubly Linked list Containsthe address of previous node and next node NULL 2000 30001000 10 15 202000 1000 2000 NULL3000 First
- 12. Circular Doubly Linkedlist Contains the address of first node and last node 3000 2000 30001000 10 15 202000 1000 2000 10003000
- 13. Operations on LinkedList Creation of the linked list Insertion of nodes Traversal of the linked list Search a specific node in the linked list Deletion of a node in the linked list
- 14. Creation of thelinked list Creation of a LL is a special case of insertion, i.e. insertion into an empty list. If the value of start is null, it implies that there are no nodes in the list. Creation is a two step process a)Creating the new node b)Storing the address of the new node in the start
- 15. 10 20 3045 X Next Creation of the Linked List Start Info Next
- 16. There arethree ways to insert a node into the list. Insertion at the beginning Insertion at the end Insertion after a particular node
- 17. There are twosteps to be followed:- a) Make the next pointer of the node point towards the first node of the list b) Make the start pointer point towards this new node If the list is empty simply make the start pointer point towards the new node;
- 19. Algorithm to Insertan Element from the front INSERT(Start,data) 1.Allocate memory to New 2. Set NewInfo=data 3.NewNext=start 4.Start=New 5.Return Start
- 20. Here we simplyneed to make the next pointer of the last node point to the new node
- 21. Here we againneed to do 2 steps :- Make the next pointer of the node to be inserted point to the next node of the node after which you want to insert the node Make the next pointer of the node after which the node is to be inserted, point to the node to be inserted
- 23. Traversal of aLL means to traverse each node of the list, and visiting each node exactly once. Algorithm: 1.Set Ptr to Start. 2.Repeat steps 3 and 4 until Ptr is not equal to Null. 3.Print the Info part of each node to which Ptr is pointing currently. 4.Advance the pointer Ptr so that it points to the next node. 5.End
- 24. a b cd start Info NextPtr
- 25. Logic using C Traverse() { Structnode *ptr; Ptr=start; While(ptr) { Print(“The current node %s”, ptritem-no); Ptr=ptrnext; } }
- 26. Searching involvesfinding the required element in the list We can use various techniques of searching like linear search or binary search where binary search is more efficient in case of Arrays But in case of linked list since random access is not available it would become complex to do binary search in it We can perform simple linear search traversal
- 27. Algorithm 1. Set Ptrto start 2. Input the item to be searched 3. While Ptr!=null do steps 4 and 5 4. Compare the item with the given value. If they are same ,exit from the loop and goto step 6, else 5. Set Ptr to next node 6. Report that the data found in the list .Otherwise it doesn’t exist .
- 28. In linear searcheach node is traversed till the data in the node matches with the required value void search(int x) { node*temp=start; while(temp!=NULL) { if(temp->data==x) { Print “FOUND ”; break; } temp=temp->next; } }
- 29. Deletion of anode is carried out in two steps viz, a) Logical deletion pointer shuffling in order to remove the links b) Physical deletion release the memory occupied using free() function Here also we have three cases:- Deleting the first node Deleting the last node Deleting the intermediate node
- 30. Here we apply3 steps:- Making the start pointer point towards the 2nd node Free the space associated with first node Operating system collects the free space of the memory and use it with available free space. The process is given by Temp=start; Start=startnext; Free(temp) threetwoone start
- 31. Here we apply2 steps:- Traverse the list to find the last node. Deleting the last node via delete keyword node3node2node1 start
- 32. Traverse thelist to find the node to be deleted. Search is used for this purpose. Refer that as curr_ptr. Then delete that node by setting the pointers as Prevnext=curr_ptrnext; Then physical deletion is achieved by free(). node1 node2 node3 To be deleted
- 33. The node inDLL may be deleted At the beginning At the end At any desired position Steps to be followed 1. If the list is empty display underflow message 2. If a single node exists, set both the pointers as Null. Else if it is the first node, then delete it and update the pointers. 3. Else if, it is the last node, then delete it and update the right pointer. 4. Restore the deleted node to the free list
- 34. Generalized listA is a finite sequence of n>=0 elements. A=(α0 ….. α n-1 ), here A name of the list and α0 ….. α n-1 represents the elements. It is either atom or a list. Name is given by capital letter and elements by small case. Ex: 1. D=() the null (or) empty list and its length is zero 2. A=(a(b,c)) a list of length 2 3. B=(A,A,()) a list of length 3, the third one is null. 4. C=(a,c) a recursive list of length 2, c corresponds to the infinite list.
- 35. Linked stack Inlinked stack we can easily add a node at the top or delete a node from the top. It is similar to push and pop the elements. A stack can be accessed only through its top element,and a linked list can be accessed by using the pointer to its first element.
- 36. 6 9 1215 Top X Null Linked Stack
- 37. Linked listrepresentations of queue are easy to handle. We need two pointers namely Front and Rear. Front represents the beginning of the queue and rear represents the end of the queue. Q.Rear=null indicates the queue is empty.
- 38. 6 9 1215 Front X Rear Null Linked Queue
- 39. 9 12 15X Null Header Linked List Header Node The header for a LL is a pointer variable that locates the beginning of the list
- 40. HLL isa LL which always contains a special node called the header node. Header node is at the beginning of the list. Dummy nodes placed as the first node of a list which is used to simplify linked list processing. It may or may not contain meaningful information. It does not represents an item in the list. The info portion of the such a header node might be unused. It is used to keep the global information about the entire list.