Add DFS with parent-completion constraint for DAG traversal

[StathisVeinoglou]

Description

This PR adds a new GraphTraversal class that implements a modified DFS traversal order for directed graphs, ensuring that a node is only visited if all its parents have already been visited.
This approach is useful in dependency resolution and neural network computation graph execution order.

• 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 77.77778% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 75.11%. Comparing base (57c6b03) to head (f0fe5f7).
⚠️ Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
...thealgorithms/graph/PredecessorConstrainedDfs.java	77.77%	6 Missing and 6 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #6467      +/-   ##
============================================
+ Coverage     75.06%   75.11%   +0.05%     
- Complexity     5540     5575      +35     
============================================
  Files           685      687       +2     
  Lines         19219    19318      +99     
  Branches       3709     3732      +23     
============================================
+ Hits          14426    14511      +85     
- Misses         4239     4245       +6     
- Partials        554      562       +8     

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[DenizAltunkapan]

could you please undo your changes? Or is there any specific reason you did this? @StathisVeinoglou

[StathisVeinoglou]

Thank you! I’ve reverted the change as requested.

[DenizAltunkapan]

Are you sure that this class name clearly reflects what your implementation does?

[StathisVeinoglou]

Thanks for the spot! I renamed it to better explain what the implementation is for.

[alxkm]

In this case, it is better to use full names. It will look more descriptive for learning purposes.

[StathisVeinoglou]

Yea good point! I believe that i replaced all abbreviated names with full descriptive ones.

[alxkm]

Will be better to use recod here:

/** An event emitted by the traversal: either a VISIT with an order, or a SKIP with a note. */
public record TraversalEvent<T>(
    T node,
    Integer order, // non-null for visit, null for skip  
    String note    // non-null for skip, null for visit
) {
    public TraversalEvent {
        Objects.requireNonNull(node);
        // order and note can be null based on event type
    }
    
    /** A visit event with an increasing order (0,1,2,...) */
    public static <T> TraversalEvent<T> visit(T node, int order) {
        return new TraversalEvent<>(node, order, null);
    }
    
    /** A skip event with an explanatory note (e.g., not all parents visited yet). */
    public static <T> TraversalEvent<T> skip(T node, String note) {
        return new TraversalEvent<>(node, null, Objects.requireNonNull(note));
    }
    
    public boolean isVisit() { return order != null; }
    public boolean isSkip() { return order == null; }
    
    @Override
    public String toString() {
        return isVisit() ? "VISIT(" + node + ", order=" + order + ")" 
                        : "SKIP(" + node + ", " + note + ")";
    }
}

[StathisVeinoglou]

Thank you, I’ve incorporated this exact record definition.

[alxkm]

Same here. Seems like it's better to use full descriptive names.

[StathisVeinoglou]

Thanks for all the suggestions! I believe that i implemented the changes.
Please let me know if anything further is needed