bfs algorithm c code example
Example 1: BFS AND DFS IN C
int n;
int adj[MAX][MAX];
int state[MAX];
void create_graph();
void BF_Traversal();
void BFS(int v);
int queue[MAX], front = -1,rear = -1;
void insert_queue(int vertex);
int delete_queue();
int isEmpty_queue();
int main()
{
create_graph();
BF_Traversal();
return 0;
}
void BF_Traversal()
{
int v;
for(v=0; v<n; v++)
state[v] = initial;
printf("Enter Start Vertex for BFS: \n");
scanf("%d", &v);
BFS(v);
}
void BFS(int v)
{
int i;
insert_queue(v);
state[v] = waiting;
while(!isEmpty_queue())
{
v = delete_queue( );
printf("%d ",v);
state[v] = visited;
for(i=0; i<n; i++)
{
if(adj[v][i] == 1 && state[i] == initial)
{
insert_queue(i);
state[i] = waiting;
}
}
}
printf("\n");
}
void insert_queue(int vertex)
{
if(rear == MAX-1)
printf("Queue Overflow\n");
else
{
if(front == -1)
front = 0;
rear = rear+1;
queue[rear] = vertex ;
}
}
int isEmpty_queue()
{
if(front == -1 || front > rear)
return 1;
else
return 0;
}
int delete_queue()
{
int delete_item;
if(front == -1 || front > rear)
{
printf("Queue Underflow\n");
exit(1);
}
delete_item = queue[front];
front = front+1;
return delete_item;
}
void create_graph()
{
int count,max_edge,origin,destin;
printf("Enter number of vertices : ");
scanf("%d",&n);
max_edge = n*(n-1);
for(count=1; count<=max_edge; count++)
{
printf("Enter edge %d( -1 -1 to quit ) : ",count);
scanf("%d %d",&origin,&destin);
if((origin == -1) && (destin == -1))
break;
if(origin>=n || destin>=n || origin<0 || destin<0)
{
printf("Invalid edge!\n");
count--;
}
else
{
adj[origin][destin] = 1;
}
}
}
Example 2: bfs algorithm
function breadthFirstSearch (Start, Goal)
{
enqueue(Queue,Start)
setVisited(start)
while notEmpty(Queue)
{
Node := dequeue(Queue)
if Node = Goal
{
return Node
}
for each Child in Expand(Node)
{
if notVisited(Child)
{
setVisited(Child)
enqueue(Queue, Child)
}
}
}
}