Breadth first search algorithm.

Breadth first search algorithm.

#include "stdio.h"
#include "conio.h"
#include "alloc.h"

#define TRUE 1
#define FALSE 0
#define MAX 8

struct node
{
int data ;
struct node *next ;
} ;

int visited[MAX] ;
int q[8] ;
int front, rear ;

void bfs ( int, struct node ** ) ;
struct node * getnode_write ( int ) ;
void addqueue ( int ) ;
int deletequeue( ) ;
int isempty( ) ;
void del ( struct node * ) ;

void main( )
{
struct node *arr[MAX] ;
struct node *v1, *v2, *v3, *v4 ;
int i ;

clrscr( ) ;

v1 = getnode_write ( 2 ) ;
arr[0] = v1 ;
v1 -> next = v2 = getnode_write ( 3 ) ;
v2 -> next = NULL ;

v1 = getnode_write ( 1 ) ;
arr[1] = v1 ;
v1 -> next = v2 = getnode_write ( 4 ) ;
v2 -> next = v3 = getnode_write ( 5 ) ;
v3 -> next = NULL ;

v1 = getnode_write ( 1 ) ;
arr[2] = v1 ;
v1 -> next = v2 = getnode_write ( 6 ) ;
v2 -> next = v3 = getnode_write ( 7 ) ;
v3 -> next = NULL ;

v1 = getnode_write ( 2 ) ;
arr[3] = v1 ;
v1 -> next = v2 = getnode_write ( 8 ) ;
v2 -> next = NULL ;

v1 = getnode_write ( 2 ) ;
arr[4] = v1 ;
v1 -> next = v2 = getnode_write ( 8 ) ;
v2 -> next = NULL ;

v1 = getnode_write ( 3 ) ;
arr[5] = v1 ;
v1 -> next = v2 = getnode_write ( 8 ) ;
v2 -> next = NULL ;

v1 = getnode_write ( 3 ) ;
arr[6] = v1 ;
v1 -> next = v2 = getnode_write ( 8 ) ;
v2 -> next = NULL ;

v1 = getnode_write ( 4 ) ;
arr[7] = v1 ;
v1 -> next = v2 = getnode_write ( 5 ) ;
v2 -> next = v3 = getnode_write ( 6 ) ;
v3 -> next = v4 = getnode_write ( 7 ) ;
v4 -> next = NULL ;

front = rear = -1 ;
bfs ( 1, arr ) ;

for ( i = 0 ; i < MAX ; i++ )
del ( arr[i] ) ;

getch( ) ;
}

void bfs ( int v, struct node **p )
{
struct node *u ;

visited[v - 1] = TRUE ;
printf ( "%d\t", v ) ;
addqueue ( v ) ;

while ( isempty( ) == FALSE )
{
v = deletequeue( ) ;
u = * ( p + v - 1 ) ;

while ( u != NULL )
{
if ( visited [ u -> data - 1 ] == FALSE )
{
addqueue ( u -> data ) ;
visited [ u -> data - 1 ] = TRUE ;
printf ( "%d\t", u -> data ) ;
}
u = u -> next ;
}
}
}

struct node * getnode_write ( int val )
{
struct node *newnode ;
newnode = ( struct node * ) malloc ( sizeof ( struct node ) ) ;
newnode -> data = val ;
return newnode ;
}

void addqueue ( int vertex )
{
if ( rear == MAX - 1 )
{
printf ( "\nQueue Overflow." ) ;
exit( ) ;
}

rear++ ;
q[rear] = vertex ;

if ( front == -1 )
front = 0 ;
}

int deletequeue( )
{
int data ;

if ( front == -1 )
{
printf ( "\nQueue Underflow." ) ;
exit( ) ;
}

data = q[front] ;

if ( front == rear )
front = rear = -1 ;
else
front++ ;

return data ;
}

int isempty( )
{
if ( front == -1 )
return TRUE ;
return FALSE ;
}

void del ( struct node *n )
{
struct node *temp ;

while ( n != NULL )
{
temp = n -> next ;
free ( n ) ;
n = temp ;
}
}