Add QuickSort implementation in Java

[Pasan11504]

📋 Pull Request Description

What does this PR add?

• New algorithm implementation

Algorithm Details

• Name: Quick Sort
• Language: Java
• Category: Sorting
• Time Complexity: O(n log n) average, O(n²) worst case
• Space Complexity: O(log n) for recursion stack

Features

• ✅ Efficient divide-and-conquer implementation using Lomuto partitioning
• ✅ Proper exception handling for null inputs
• ✅ Comprehensive test cases (5 different scenarios)
• ✅ Complete JavaDoc documentation with complexity analysis
• ✅ Handles edge cases: empty arrays, single elements, duplicates, negatives
• ✅ Follows Java naming conventions and repository standards
• ✅ In-place sorting with optimal space complexity

Testing

• Code compiles without errors or warnings
• All test cases pass (regular, sorted, reverse, single, empty)
• Edge cases handled properly (null arrays, duplicates)
• Performance tested with large arrays
• Documentation complete with time/space complexity

Code Quality

• 8+ meaningful comments explaining algorithm logic
• Proper Java naming conventions (PascalCase for class, camelCase for methods)
• Complete JavaDoc for all public methods
• Exception handling with descriptive messages
• Clean, readable code structure

Files Added

• Java/algorithms/sorting/QuickSort.java - Complete QuickSort implementation

Checklist

• Algorithm is not a duplicate (QuickSort was missing in Java)
• File is in correct directory structure
• Follows repository coding standards
• No compiled .class files included
• Original implementation (not copy-pasted)

Contributes to Hacktoberfest 2025 🎃

Additional Notes

This implementation adds the missing QuickSort algorithm to the Java sorting collection. The algorithm uses the Lomuto partition scheme for simplicity and includes comprehensive error handling and testing that exceeds repository standards.

[github-actions]

🎉 Welcome to Hacktoberfest 2025, @Pasan11504! 🎃

Thank you for your first contribution to our DSA repository! Here's what happens next:

🔍 Automatic Checks

• ✅ Code Validation: Passed
• 🧪 Compilation Tests: Passed

📋 Next Steps

🎯 Great job! Your code compiled successfully. Maintainers @Karanjot786 and @Pradeepsingh61 will review your PR soon.

🎁 What You Get

• 🏆 Hacktoberfest Credit: This PR counts toward your 6 PR goal for exclusive T-shirt + Tree!
• 🌟 Hall of Fame: You'll be featured in our contributors list
• 📚 Learning: Code review feedback from experienced developers

💡 Tips for Success

• Follow our Contributing Guidelines
• Add comments explaining your algorithm
• Include time/space complexity analysis
• Test your code before submitting

Welcome to the community! 🚀

[github-actions]

🤖 Automated PR Status

🔍 Code Validation

✅ Passed - File naming and structure look good!

🧪 Compilation Tests

✅ Passed - All code compiles successfully!

📋 Overall Status

🎉 Ready for Review - Your PR has passed all automated checks!
👥 Maintainers have been notified for review.

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[Karanjot786]

@Pradeepsingh61 merge it