# Program for implementing Breadth First Search

/*In graph theory,  Breadth First Search (BFS) is a technique for searching in a graph when search is limited to essentially two operations: (a) visit and inspect a node of a graph; (b) gain access to visit the nodes that neighbor the currently visited node. The BFS begins at a root node and inspects all the neighboring nodes. Then for each of those neighbor nodes in turn, it inspects their neighbor nodes which were unvisited, and so on. */

#include<stdio.h>

#include<conio.h>

int a,q,visited,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++]);

}

}

## Also Read : Program for implementing Depth First Search

int main()

{   int v;

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 Breadth First Search is not possible”);

getch();

return 0;

}

Output:   