Lecture 6: linked list
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This document provides an overview of linked lists in C++. It discusses how to represent a linked list node using a struct with a data field and pointer to the next node. It demonstrates how to traverse a linked list by accessing the data and next fields of each node. Several examples are provided for linked list operations like inserting and deleting nodes at different positions within the list.
Lecture 6: linked list
- 1. Placement Preparation Linked List Shobhit Chaurasia B.Tech, CSE
- 2. Target Audience People who have coding experience limited to the basic syntax of C++, pointers and structures, but didn’t take CS101 seriously and want to learn some basics of coding quickly. If you already know how to implement a linked list, then please spare me the pain of taking a lecture on linked lists, and volunteer to deliver this lecture.
- 3. Motivation Suppose I have an array: 1,4,10,19,6 I want to insert a 7 between the 4 and the 10 What do we need to do?
- 5. Node
- 6. How to represent a Node in C++ ? How to represnt integers in C++? int x; But Node is a combination of data + pointer (int) + pointer (char) + pointer (string) + pointer
- 7. Structures Revisited Structure variable stud s; Access members of struct ; s.rollNo = 11010179 s.cpi = 8.1 s.gender = ‘M’
- 8. How to represent Node in C++ ;
- 9. Head Pointer to the first node. Holds the address of the first node in the list head
- 10. Head Pointer to the first node. node* head ;
- 11. Struct Pointer revisited Struct Pointer stud *s; Access members of struct s->rollNo = 11010179 s->cpi = 8.1 s->gender = ‘M’ rollNo cpi gender s ;
- 12. Accessing data/next node node* head Data stored at first node head->data = ‘a’; Pointer to second node head->next Data stored at second node (head->next)->data = ‘b’; head ;
- 13. Demo #0(a) node* temp; temp = head; cout<<temp->data; head
- 14. Demo #0(a) How to go to the second node? temp = temp->next; cout<<temp->data; head
- 15. Demo #0(a) How to go to the third node? temp = temp->next; cout<<temp->data; head
- 16. Where’s the list’s end? head ptr
- 17. Demo #0(b) Printing the linked list
- 18. Demo #0(b) Printing the linked list (correct version)
- 19. Demo #0(b) An observation
- 20. Demo #0(b) - MORAL Never move the HEAD while traversing a linked list
- 21. Demo #1 Function to print the 3rd element in linked list
- 22. Insert a new node at the end node* temp; temp = start; temp->next == NULL ??
- 23. Insert a new node at the end temp = temp->next; temp->next == NULL ??
- 24. Insert a new node at the end temp = temp->next; temp->next == NULL ??
- 25. Insert a new node at the end temp = temp->next; temp->next == NULL ??
- 26. Insert a new node at the end temp = temp->next; temp->next == NULL ?? (YES!! Finally reached the end)
- 27. Insert a new node at the end node* ptr = new node ptr
- 28. Insert a new node at the end ptr ptr->data = ‘f’; ptr->next = NULL; f
- 29. Insert a new node at the end ptr temp->next = ptr;
- 30. Demo #2 Inserting a new node at the end. Discuss 2.cpp
- 31. Insert a new node at the start node* ptr = new node; ptr
- 32. Insert a new node at the start node* ptr = new node; ptr->data = ‘z’; z ptr
- 33. Insert a new node at the start ptr->next = start; ptr
- 34. Insert a new node at the start start = ptr; ptr
- 35. Demo #3 Insert a new node at the head Discuss 3.cpp (two methods)
- 36. Demo #4 Create a linked list and print its contents.
- 37. Demo #5 Same as last problem. Use functions.
- 38. Insert after a particular node
- 39. Demo #6 Write a function which takes as parameter a node pointer and inserts a new node after it. insertInBetween (node* temp)
- 42. ACTUALLY Deleting first node
- 43. ACTUALLY Deleting first node
- 44. ACTUALLY deleting first node
- 45. ACTUALLY deleting first node delete frees the memory allocated by new
- 46. Demo #7 Write a function to delete the first node of a linked list. Add this function to 5.cpp
- 47. Demo #8 Write a function to delete the last node of linked list Add this function to 7.cpp
- 48. Delete a node inside the linked list
- 49. Delete a node inside the linked list
- 50. Locating the node “y”
- 51. Can we delete the node “y” now? Having just the pointer to the node containing “y” sufficient to delete it?
- 52. What do we want to do? Break this link, and make it point to the node “d”
- 53. Expected Output
- 54. What do we need? Pointer to the previous node
- 55. Step 1 prev->next = temp->next;
- 56. Step 2 delete temp;
- 57. Final output
- 58. Demo #9 Delete the node with data = 3 Add this function to 5.cpp
- 59. Homework Reverse a linked list.
- 60. Linked list vs Arrays Operation Linked List Array Insert at start O(1) O(n) Insert anywhere O(1) O(n) Delete anywhere O(1) O(n) Access ith element O(n) O(1)
- 61. THANK YOU