Breath First Search Implementation In Java

Breath First Search Implementation In Java 
Graph Traversals

import java.io.*;
import java.util.*;

class Queue
{
                 int items[]=new int[10];
    int front,rear;

    Queue()
    {
        front=0;
        rear=-1;
    }

    void insert(int e)
    {
    if(rear==9)
            System.out.println(“Queue overflow”);
        else
        {

            items[++rear]=e;
        }
    }

    int empty()
    {
        return(rear<front? 1:0);
    }

    int remove()
    {
        int x=0;
        if(empty()==1)
        {
            System.out.println(“Queue Underflow”);
            return 0;
        }

        else
        {
            x=items[front++];

            return x;
        }
       
    }
}

class Graph
{
    int MAXSIZE=51;
    int adj[][]=new int[MAXSIZE][MAXSIZE];
    int visited[]=new int [MAXSIZE];
    Queue q=new Queue();

    void createGraph()throws IOException
    {
        int n,i,j,parent,adj_parent,initial_node;
        int  ans=0,ans1=0;
         BufferedReader in=new BufferedReader( new InputStreamReader(System.in));
        System.out.print(“nEnter total number elements in a Undirected Graph :”);
        n=Integer.parseInt(in.readLine());
        for ( i=1;i<=n;i++)
            for( j=1;j<=n;j++)
                adj[i][j]=0;

        for (int c=1;c<=50;c++)
            visited=0;
        System.out.println(“nEnter graph structure for BFS  “);

        do
        {
            System.out.print(“nEnter parent node :”);
            parent=Integer.parseInt(in.readLine());
            do
            {
                System.out.print(“nEnter adjacent node for node “+parent+ ” : “);
                adj_parent=Integer.parseInt(in.readLine());
                adj[parent][adj_parent]=1;
                adj[adj_parent][parent]=1;
                System.out.print(“nContinue to add adjacent node for “+parent+”(1/0)?”);
                ans1= Integer.parseInt(in.readLine());
            } while (ans1==1);

            System.out.print(“nContinue to add graph node press 1?”);
            ans= Integer.parseInt(in.readLine());
        }while (ans ==1);

        System.out.print(“nAdjacency matrix for your graph is :n”);
        for (i=1;i<=n;i++)
        {
            for (j=1;j<=n;j++)
                System.out.print(” “+adj[i][j]);
            System.out.print(“n”);
        }

        System.out.println(“nYour Undirected Graph is :”);
        for (i=1;i<=n;i++)
        {
            System.out.print(“nVertex “+i+”is connected to : “);
            for (j=1;j<=n;j++)
            {
                if (adj[i][j]==1)
                System.out.print(” “+j);
            }
        }
        System.out.println(“nEnter the initial node for BFS traversal:”);
        initial_node=Integer.parseInt(in.readLine());
        BFS (initial_node, n);
    }

     void BFS (int initial_node,int n)
    {
      int u,i;
      u = initial_node;
      visited[initial_node]=1;
      System.out.println(“nBFS traversal for given graph is : “);
      System.out.print(initial_node);
      q.insert(initial_node);
      while(q.empty()==0)
      {
                u = q.remove();
                  for (i=1;i<=n;i++)
                 {
                    if((adj[u][i]==1) && (visited[i]==0))
                    {
                      q.insert(i);
                      visited[i]=1;
                      System.out.print(” “+i);
                     }
                  }
        }
    }

}

class bgraph
{
public static void main(String args[])throws IOException
{
    Graph g=new Graph();
    g.createGraph();
}
}

/*
Enter total number elements in a Undirected Graph :7

Enter graph structure for BFS

Enter parent node :1

Enter adjacent node for node 1 : 2

Continue to add adjacent node for 1(1/0)?1

Enter adjacent node for node 1 : 3

Continue to add adjacent node for 1(1/0)?0

Continue to add graph node press 1?1

Enter parent node :2

Enter adjacent node for node 2 : 4

Continue to add adjacent node for 2(1/0)?1

Enter adjacent node for node 2 : 5

Continue to add adjacent node for 2(1/0)?0

Continue to add graph node press 1?1

Enter parent node :3

Enter adjacent node for node 3 : 6

Continue to add adjacent node for 3(1/0)?1

Enter adjacent node for node 3 : 7

Continue to add adjacent node for 3(1/0)?0

Continue to add graph node press 1?0

Adjacency matrix for your graph is :
 0 1 1 0 0 0 0
 1 0 0 1 1 0 0
 1 0 0 0 0 1 1
 0 1 0 0 0 0 0
 0 1 0 0 0 0 0
 0 0 1 0 0 0 0
 0 0 1 0 0 0 0

Your Undirected Graph is :

Vertex 1is connected to :  2 3
Vertex 2is connected to :  1 4 5
Vertex 3is connected to :  1 6 7
Vertex 4is connected to :  2
Vertex 5is connected to :  2
Vertex 6is connected to :  3
Vertex 7is connected to :  3
Enter the initial node for BFS traversal:
1

BFS traversal for given graph is :
1 2 3 4 5 6 7

Enter total number elements in a Undirected Graph :9

Enter graph structure for BFS

Enter parent node :1

Enter adjacent node for node 1 : 2

Continue to add adjacent node for 1(1/0)?1

Enter adjacent node for node 1 : 3

Continue to add adjacent node for 1(1/0)?0

Continue to add graph node?1

Enter parent node :2

Enter adjacent node for node 2 : 4

Continue to add adjacent node for 2(1/0)?1

Enter adjacent node for node 2 : 5

Continue to add adjacent node for 2(1/0)?0

Continue to add graph node?1

Enter parent node :3

Enter adjacent node for node 3 : 5

Continue to add adjacent node for 3(1/0)?0

Continue to add graph node?1

Enter parent node :4

Enter adjacent node for node 4 : 6

Continue to add adjacent node for 4(1/0)?1

Enter adjacent node for node 4 : 7

Continue to add adjacent node for 4(1/0)?0

Continue to add graph node?1

Enter parent node :5

Enter adjacent node for node 5 : 8

Continue to add adjacent node for 5(1/0)?0

Continue to add graph node?1

Enter parent node :6

Enter adjacent node for node 6 : 9

Continue to add adjacent node for 6(1/0)?0

Continue to add graph node?0

Adjacency matrix for your graph is :
 0 1 1 0 0 0 0 0 0
 1 0 0 1 1 0 0 0 0
 1 0 0 0 1 0 0 0 0
 0 1 0 0 0 1 1 0 0
 0 1 1 0 0 0 0 1 0
 0 0 0 1 0 0 0 0 1
 0 0 0 1 0 0 0 0 0
 0 0 0 0 1 0 0 0 0
 0 0 0 0 0 1 0 0 0

Your Undirected Graph is :

Vertex 1is connected to :  2  3

Vertex 2is connected to :  1  4  5

Vertex 3is connected to :  1  5

Vertex 4is connected to :  2  6  7

Vertex 5is connected to :  2  3  8

Vertex 6is connected to :  4  9

Vertex 7is connected to :  4

Vertex 8is connected to :  5

Vertex 9is connected to :  6

Enter the initial node for BFS traversal:
1

BFS traversal for given graph is :
1 2 3 4 5 6 7 8 9
*/