C++ Program to Traverse a Graph using BFS

This C++ program displays the breadth first traversal of all nodes present in a graph. A graph is a set of nodes connected by edges.

Here is the source code of the C++ program to display the breadth first method of traversing nodes in a graph along with a display of the start and end time of a visited node. This C++ program is successfully compiled and run on DevCpp, a C++ compiler. The program output is given below.

```
/*
```

 * C Program to Traverse a Graph using BFS

```
 */
```
```
#include <iostream>
```
```
#include <conio.h>
```
```
using namespace std;
```
```
int c = 0, t = 0;
```
```
struct node_info
```
```
{
```
```
    int no;
```
```
    int st_time;
```
```
}*q = NULL, *r = NULL, *x = NULL;
```
```
struct node
```
```
{
```
```
    node_info *pt;
```
```
    node *next;
```

}*front = NULL, *rear = NULL, *p = NULL, *np = NULL;

```
void push(node_info *ptr)
```
```
{
```
```
    np = new node;
```
```
    np->pt = ptr;
```
```
    np->next = NULL;
```
```
    if (front == NULL)
```
```
    {
```
```
        front = rear = np;
```
```
        rear->next = NULL;
```
```
    }
```
```
    else
```
```
    {
```
```
        rear->next = np;
```
```
        rear = np;
```
```
        rear->next = NULL;
```
```
    }
```
```
}
```
```
node_info *remove()
```
```
{
```
```
    if (front == NULL)
```
```
    {
```
```
        cout<<"empty queue\n";
```
```
    }
```
```
    else
```
```
    {
```
```
        p = front;
```
```
        x = p->pt;
```
```
        front = front->next;
```
```
        delete(p);
```
```
        return(x);
```
```
    }
```
```
}
```
```
void bfs(int *v,int am[][7],int i)
```
```
{ 
```
```
    if (c == 0)
```
```
    {
```
```
        q = new node_info;
```
```
        q->no = i;
```
```
        q->st_time = t++;
```

        cout<<"time of visitation for node "<<q->no<<":"<<q->st_time<<"\n\n";

```
        v[i] = 1;
```
```
        push(q);
```
```
    }
```
```
    c++;
```
```
    for (int j = 0; j < 7; j++)
```
```
    {
```

        if (am[i][j] == 0 || (am[i][j] == 1 && v[j] == 1))

```
            continue;
```

        else if (am[i][j] == 1 && v[j] == 0)

```
        {
```
```
            r = new node_info;
```
```
            r->no = j;
```
```
            r->st_time = t++;
```

            cout<<"time of visitation for node "<<r->no<<":"<<r->st_time<<"\n\n";

```
            v[j] = 1;
```
```
            push(r);
```
```
        }
```
```
    }
```
```
    remove();
```
```
    if (c <= 6 && front != NULL)
```
```
        bfs(v, am, remove()->no);
```
```
}  
```
```
int main()
```
```
{
```
```
    int v[7], am[7][7];
```
```
    for (int i = 0; i < 7; i++)
```
```
        v[i] = 0;
```
```
    for (int i = 0; i < 7; i++)
```
```
    {
```

        cout<<"enter the values for adjacency matrix row:"<<i+1<<endl;

```
        for (int j = 0; j < 7; j++)
```
```
        {
```
```
            cin>>am[i][j];
```
```
        }
```
```
    }
```
```
    bfs(v, am, 0);
```
```
    getch();
```
```
}
```

Output
enter the values for adjacency matrix row:1
0
1
1
0
0
1
1
enter the values for adjacency matrix row:2
1
0
0
0
0
0
0
enter the values for adjacency matrix row:3
1
0
0
0
0
0
1
enter the values for adjacency matrix row:4
0
0
0
0
1
1
0
enter the values for adjacency matrix row:5
0
0
0
1
0
1
1
enter the values for adjacency matrix row:6
1
0
0
1
1
0
0
enter the values for adjacency matrix row:7
1
0
1
0
1
0
0
time of visitation for node 0:0
 
time of visitation for node 1:1
 
time of visitation for node 2:2
 
time of visitation for node 5:3
 
time of visitation for node 6:4
 
time of visitation for node 3:5
 
time of visitation for node 4:6

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