programming-examples/java/Graph_Problems_Algorithms/Java Program to Check whether Undirected Graph is Connected using BFS.java
2019-11-15 12:59:38 +01:00

107 lines
3.5 KiB
Java

import java.util.InputMismatchException;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;
public class UndirectedConnectivityBFS
{
private Queue<Integer> queue;
public UndirectedConnectivityBFS()
{
queue = new LinkedList<Integer>();
}
public void bfs(int adjacency_matrix[][], int source)
{
int number_of_nodes = adjacency_matrix[source].length - 1;
int[] visited = new int[number_of_nodes + 1];
int i, element;
visited[source] = 1;
queue.add(source);
while (!queue.isEmpty())
{
element = queue.remove();
i = element;
while (i <= number_of_nodes)
{
if (adjacency_matrix[element][i] == 1 && visited[i] == 0)
{
queue.add(i);
visited[i] = 1;
}
i++;
}
}
boolean connected = false;
for (int vertex = 1; vertex <= number_of_nodes; vertex++)
{
if (visited[vertex] == 1)
{
connected = true;
}
else
{
connected = false;
break;
}
}
if (connected)
{
System.out.println("The graph is connected");
}
else
{
System.out.println("The graph is disconnected");
}
}
public static void main(String... arg)
{
int number_no_nodes, source;
Scanner scanner = null;
try
{
System.out.println("Enter the number of nodes in the graph");
scanner = new Scanner(System.in);
number_no_nodes = scanner.nextInt();
int adjacency_matrix[][] = new int[number_no_nodes + 1][number_no_nodes + 1];
System.out.println("Enter the adjacency matrix");
for (int i = 1; i <= number_no_nodes; i++)
for (int j = 1; j <= number_no_nodes; j++)
adjacency_matrix[i][j] = scanner.nextInt();
for (int i = 1; i <= number_of_nodes; i++)
{
for (int j = 1; j <= number_of_nodes; j++)
{
if (adjacency_matrix[i][j] == 1 && adjacency_matrix[j][i] == 0)
{
adjacency_matrix[j][i] = 1;
}
}
}
System.out.println("Enter the source for the graph");
source = scanner.nextInt();
UndirectedConnectivityBFS undirectedConnectivity= new UndirectedConnectivityBFS();
undirectedConnectivity.bfs(adjacency_matrix, source);
}
catch (InputMismatchException inputMismatch)
{
System.out.println("Wrong Input Format");
}
scanner.close();
}
}
/*
Enter the number of nodes in the graph
5
Enter the adjacency matrix
0 1 1 1 0
0 0 1 0 0
0 0 0 0 0
0 0 0 0 0
0 0 0 0 0
Enter the source for the graph
1
The graph is disconnected