This slide is part of course designed for placement preparation for students of IIT Guwahati.

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?

4. Linked List
head

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)

40. Deleting first node

41. Deleting first node

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