1. Linear and Non-Linear Data Structures: Linked lists, stacks and queues.

2. Data structure types

4. Structures
A compound user defined data type containing elements of basic data types

5. Problem 1
main(){ char name[3][10] ; float price[3] ; int pages[3],i ; printf("\nEnter names, prices, pages of 3 books\n" ) ; for(i=0;i<3;i++) scanf("%s %f %d",&name[i],&price[i],&pages[i] ); printf("\n You entered\n" ) ; printf("%s %f %d\n",name[i],price[i],pages[i]); }

6. Output
Enter names, prices, pages of 3 books letusC Physics Math You entered letusC Physics Math

7. Defining and using structure
struct book{ char name[10]; float price; int pages; }; struct book b[3];

8. main( ){ struct book{ char name[10]; float price; int pages; }; struct book b[3]; int i; printf ( "\nEnter names,prices,pages of 3 books\n" ) ; for(i=0;i<3;i++) scanf("%s%f%d",&b[i].name, &b[i].price, &b[i].pages ); printf ( "\nAnd this is what you entered" ) ; printf("\n%s %f %d", b[i].name, b[i].price, b[i].pages ) ; } Q2

9. Output
Enter names,prices,pages of 3 books letusc math physics And this is what you entered letusc math physics

10. Initialization
struct book b1 = { "Basic", , 550 } ; printf("%s %f %d", b1.name, b1.price, b1.pages );

11. Assignment operator
struct book b1 = { "Basic", , 550 },b2=b1; struct book b3; strcpy ( b3.name, b2.name ) ; B3.price = b1.price;

12. Nested structures
main(){ struct Inner{ int i; }; struct Outer{ struct Inner I; struct Outer O; O.I.i = 999; printf(" %d",O.I.i); }

13. Dot versus arrow operator
Dot operator is performed on structure variables
Arrow operator is performed on structure pointers

14. . Versus -> operator
main(){ struct A{ int i; }; struct A a, *b; a.i=99; b=&a; printf("%d and %d",a.i, b->i); }

15. Structures in functions
struct A{ int i; float f; }; main(){ struct A a={-5,2.43}; fun(a); } fun(struct A a){ printf("%d and %f",a.i, a.f);

16. Program exercise
WAP to swap structures using functions and pointers

17. Linear Data structures
Stack – last in first out (LIFO)
Queue – first in first out (FIFO)
Link list – Insertion/deletion at any given location

18. Insertion is done on the top
Insertion is called push
Deletion is called pop

20. Queue First in first out Insertion is called enqueue
Deletion is called dequeue
Two positions are maintained – first and last

23. Linked list General name for a list of linked elements using pointers
Dynamic memory allocation
Insertion and deletion can be done at any given location
Need to save the address of first node (element)

24. A general linked list

25. Linked list versus stacks and queue
A linked list can be a stack or a queue depending upon the nature of operations

26. Node – the basic element

27. Example of a linked list

28. Define the node outside main()
struct Node{ int data; struct Node *next; }; struct Node* first = NULL; main(){}

29. Create and delete a node
struct Node *anode = (struct Node*)malloc(sizeof(struct Node));
anode->data = somedata;
anode->next = somepointer; ….
free(anode);

30. Traverse/display stack
void Traverse(struct Node *n) { while (n != NULL) { printf(" %d ",n->data); n = n->next; }

31. Stack Implementation
struct Node{ int data; struct Node *next; }; struct Node* first = NULL; main() { int i; for(i=0;i<4;i++) { Push(i); Traverse(first);} for(i=0;i<4;i++) { Pop(); Traverse(first); }}

32. Stack continued..
void Push(int data){ struct Node *anode = (struct Node*)malloc(sizeof(struct Node)); anode->data = data; anode->next = first; first=anode; } void Pop(){ struct Node *temp; temp = first->next; printf(“\n Popped element = %d”,first->data); free(first); first = temp;

33. Stack continued..
void Traverse(struct Node *n) { printf("\n Stack is: "); while (n != NULL) { printf(" %d ",n->data); n = n->next; } }

34. Queue implementation
struct Node{ int data; struct Node *next; }; struct Node *first=NULL, *last=NULL;

35. Queue continued…
main(){ int i; for(i=0;i<5;i++){ Enqueue(i); Traverse(); } Dequeue(); Traverse(); }}

36. Queue continued…
Enqueue(int i){ struct Node *temp = (struct Node* ) malloc(sizeof(struct Node)); temp->data = i; temp->next = NULL; if(first==NULL) first = last = temp; else {last->next = temp; last = temp;} }

37. Queue continued…
Dequeue(){ struct Node *temp; temp = first->next; printf(“\n Dequeued = %d”,first->data); free(first); first = temp; }

38. Queue continued…
Traverse(){ struct Node*temp = first; printf("\n Queue is - "); while(temp!=NULL){ printf(" %d",temp->data); temp=temp->next;} }

39. Link list
WAP program to insert and delete node at any given location

40. Insertion and deletion

41. Link list insertion – 3 cases
Insert at the beginning
Insertion at the end
Insertion in between

42. Insertion (1)
#include<stdio.h> struct Node{ int data; struct Node *next; }; struct Node *first=NULL; int count=0; //number of nodes count

43. Insertion (2)
main(){ int pos=2; //choose pos for insertion Insert(10,1);Traverse(); Insert(20,2);Traverse(); Insert(30,3);Traverse(); Insert(555,pos);Traverse(); }

44. Insert(int data, int pos){ int i=1; struct Node
Insert(int data, int pos){ int i=1; struct Node *temp=first; struct Node *anode = (struct Node*)malloc(sizeof(struct Node)); anode->data = data; if(count==0){anode->next=NULL; first = anode; } else if(pos==1){ anode->next = first; first = anode;} else if(pos==count+1){ while(temp->next!=NULL) temp=temp->next; anode->next = NULL; temp->next = anode; } else if(pos>1&&pos<=count){ while(i++<pos-1) {temp=temp->next; } anode->next = temp->next; temp->next = anode; //printf("\nHERE"); }count++; }
Insertion(3)

45. Insertion (4)
Traverse(){ struct Node*temp = first; printf("\nLinklist - "); while(temp!=NULL){ printf(" %d",temp->data); temp=temp->next;} }

46. Exercise: Delete a given node
Consider cases for node to be deleted: first, last or other node.
Find previous node of the node to be deleted.
Change the next of previous node.
Free memory for the node to be deleted.