This Java program,performs the DFS traversal on the given undirected graph represented by a adjacency matrix to check connectivity.the DFS traversal makes use of an stack.

Here is the source code of the Java program to check the connectivity of a undirected graph. The Java program is successfully compiled and run on a Linux system. The program output is also shown below.

import java.util.InputMismatchException;

import java.util.Scanner;

import java.util.Stack;

public class UndirectedConnectivityDfs

`{`

private Stack<Integer> stack;

public UndirectedConnectivityDfs()

`{`

stack = new Stack<Integer>();

`}`

public void dfs(int adjacency_matrix[][], int source)

`{`

int number_of_nodes = adjacency_matrix[source].length - 1;

int visited[] = new int[number_of_nodes + 1];

int element = source;

int i = source;

visited[source] = 1;

stack.push(source);

while (!stack.isEmpty())

`{`

element = stack.peek();

i = element;

while (i <= number_of_nodes)

`{`

if (adjacency_matrix[element][i] == 1 && visited[i] == 0)

`{`

stack.push(i);

visited[i] = 1;

element = i;

i = 1;

continue;

`}`

`i++;`

`}`

stack.pop();

`}`

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_of_nodes, source;

Scanner scanner = null;

`try`

`{`

System.out.println("Enter the number of nodes in the graph");

scanner = new Scanner(System.in);

number_of_nodes = scanner.nextInt();

int adjacency_matrix[][] = new int[number_of_nodes + 1][number_of_nodes + 1];

System.out.println("Enter the adjacency matrix");

for (int i = 1; i <= number_of_nodes; i++)

for (int j = 1; j <= number_of_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();

UndirectedConnectivityDfs undirectedConnectivity= new UndirectedConnectivityDfs();

undirectedConnectivity.dfs(adjacency_matrix, source);

}catch(InputMismatchException inputMismatch)

`{`

System.out.println("Wrong Input format");

`}`

scanner.close();

`}`

`}`

$javac UndirectedConnectivityDfs.java $java UndirectedConnectivityDfs Enter the number of nodes in the graph 5 Enter the adjacency matrix 0 1 0 1 0 0 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 Enter the source for the graph 1 The graph is disconnected

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