This Java program,to perform the topological Sort on a given graph by the DFS method.The topological sort is performed on a directed acyclic graph.
Here is the source code of the Java program to check for cycle in topological sort. 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 TopoCycle
{
private Stack<Integer> stack;
public TopoCycle()
{
stack = new Stack<Integer>();
}
public boolean checkCycle(int adjacency_matrix[][], int source)
{
int number_of_nodes = adjacency_matrix[source].length - 1;
int[] topological_sort = new int [number_of_nodes + 1];
int pos = 1;
int j;
boolean cycle = false;
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();
while (i <= number_of_nodes)
{
if (adjacency_matrix[element][i] == 1 && visited[i] == 1)
{
if (stack.contains(i))
{
System.out.println("The Graph Contains a cycle");
cycle = true;
return cycle;
}
}
if (adjacency_matrix[element][i] == 1 && visited[i] == 0)
{
stack.push(i);
visited[i] = 1;
element = i;
i = 1;
continue;
}
i++;
}
j = stack.pop();
topological_sort[pos++] = j;
i = ++j;
}
System.out.println("The Graph does not Contain cycle");
return cycle;
}
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();
System.out.println("Enter the source for the graph");
source = scanner.nextInt();
TopoCycle topoCycle = new TopoCycle();
topoCycle.checkCycle(adjacency_matrix, source);
}catch(InputMismatchException inputMismatch)
{
System.out.println("Wrong Input format");
}
scanner.close();
}
}
$javac TopoCycle.java $java TopoCycle 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 1 0 1 0 0 1 0 0 0 1 0 Enter the source for the graph 1 The Graph contains a cycle
Sanfoundry Global Education & Learning Series – 1000 Java Programs.
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