It is an algorithm to find cycle in the graph if any otherwise the graph is acyclic and will give the topological ordering of the graph.
Following are some test cases:

Enter the numer of vetrices:
4
Enter the numer of edges:
3
Enter e edges
0 1
1 3
2 3
Output : 0 2 1 3

Enter the numer of vetrices:
4
Enter the numer of edges:
4
Enter e edges
0 1
1 2
3 1
2 0
Output :The graph has cycle

Describe your change:

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Documentation change?

References

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new Java files are placed inside an existing directory.
• All filenames are in all uppercase characters with no spaces or dashes.
• All functions and variable names follow Java naming conventions.
• All new algorithms have a URL in its comments that points to Wikipedia or other similar explanation.
• If this pull request resolves one or more open issues then the commit message contains Fixes: #{$ISSUE_NO}.