C Program to implement Breadth First Search (BFS)


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Breadth First Search is an algorithm used to search the Tree or Graph. BFS search starts from root node then traversal into next level of graph or tree and continues, if item found it stops other wise it continues.


The disadvantage of BFS is it requires more memory compare to Depth First Search(DFS).




For More Go To Data Structure section



C Program

#include<stdio.h>
#include<conio.h>
int a[20][20],q[20],visited[20],n,i,j,f=0,r=-1;
void bfs(int v) {
	for (i=1;i<=n;i++)
	  if(a[v][i] && !visited[i])
	   q[++r]=i;
	if(f<=r) {
		visited[q[f]]=1;
		bfs(q[f++]);
	}
}
void main() {
	int v;
	clrscr();
	printf("\n Enter the number of vertices:");
	scanf("%d",&n);
	for (i=1;i<=n;i++) {
		q[i]=0;
		visited[i]=0;
	}
	printf("\n Enter graph data in matrix form:\n");
	for (i=1;i<=n;i++)
	  for (j=1;j<=n;j++)
	   scanf("%d",&a[i][j]);
	printf("\n Enter the starting vertex:");
	scanf("%d",&v);
	bfs(v);
	printf("\n The node which are reachable are:\n");
	for (i=1;i<=n;i++)
	  if(visited[i])
	   printf("%d\t",i); else
	   printf("\n Bfs is not possible");
	getch();
}





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