Implement topological sort with DAG validation and cycle detection

[the-yash-rajput]

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized it.
• All filenames are in PascalCase.
• All functions and variable names follow Java naming conventions.
• All new algorithms have a URL in their comments that points to Wikipedia or other similar explanations.
• All new code is formatted with clang-format -i --style=file path/to/your/file.java

[codecov-commenter]

Codecov Report

❌ Patch coverage is 94.73684% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 75.22%. Comparing base (421ac6d) to head (88f2467).

Files with missing lines	Patch %	Lines
.../java/com/thealgorithms/graph/TopologicalSort.java	94.73%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #6568      +/-   ##
============================================
+ Coverage     75.19%   75.22%   +0.03%     
- Complexity     5614     5625      +11     
============================================
  Files           690      691       +1     
  Lines         19407    19445      +38     
  Branches       3755     3763       +8     
============================================
+ Hits          14593    14628      +35     
- Misses         4247     4250       +3     
  Partials        567      567              

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[alxkm]

Looks like this is already in the repository, but in the wrong package it is definitely related to the graph

https://github.com/TheAlgorithms/Java/blob/master/src/main/java/com/thealgorithms/sorts/TopologicalSort.java

[the-yash-rajput]

@alxkm How would you like to proceed?
Should we merge this PR or replace the previous implementation with the correct location?

@alxkm I think we can include both, as the previous algorithm is not more friendly to graphs.

[alxkm]

@siriak, @DenizAltunkapan, Could you please help clarify our approach here?

There are already several implementations of this algorithm in the repository:

The previous implementation follows a more traditional pattern as it operates directly on color values.
The current implementation also good and it has test coverage.

From my perspective, the optimal solution would be to:

• Migrate the old implementation here
• Make it generic
• Clean up the code (e.g., implement specialized exceptions which already presented here)
• Maintain test suites for both variants

What are your thoughts on this approach?

[the-yash-rajput]

@alxkm Let’s first align on the right strategy and once confirmed, we can proceed with the necessary implementation.

[alxkm]

@the-yash-rajput, you can proceed with the following approach as I described - creating a generic implementation of the algorithm.

• Migrate the existing implementation to the correct package location
• Refactor it to be generic and reusable
• Implement the specialized exceptions that are already present in the your version
• And generic tests for it with Integer and String values

This approach will provide the traditional algorithm that uses color values.

What do you think about this?

[siriak]

@alxkm I agree with the proposed approach, I think both implementations should be stored together.

P.S. I reviewed this 2 days ago, but forgot to write a reply and then lost the tab -_-