Add Binary Search Tree (BST) data structure implementation [HACKTOBERFEST 2025]

[piyushkumar0707]

🚀 Overview

This PR implements a complete Binary Search Tree (BST) data structure using R6 object-oriented programming - providing the foundation for advanced tree-based algorithms and data management.

✨ Features

• ✅ Complete BST implementation - All fundamental operations with optimal complexity
• ✅ R6 object-oriented design - Professional, maintainable code structure
• ✅ Four traversal methods - Inorder, preorder, postorder, level-order
• ✅ Tree visualization - ASCII art representation for debugging
• ✅ Advanced operations - Height calculation, BST validation, kth smallest
• ✅ Real-world examples - Student grade management system

🎯 Why This Matters

Binary Search Trees are fundamental for:

• Database indexing - B-trees and B+ trees are BST variants
• Expression parsing - Syntax trees in compilers
• Priority queues - Efficient priority-based operations
• File system organization - Directory structure representation
• Game AI - Decision trees and minimax algorithms
• Computer science education - Core data structure concepts

📚 Implementation Details

• Time Complexity: O(log n) average for search, insert, delete
• Space Complexity: O(n) for tree storage, O(log n) for recursion
• Worst Case: O(n) when tree becomes skewed
• Self-balancing: Foundation for AVL and Red-Black trees

🔧 Core Operations

Basic Operations:

• insert(value) - Add new node maintaining BST property
• search(value) - Find if value exists in tree
• delete(value) - Remove node with three deletion cases
• find_min() / find_max() - Find extreme values

Traversal Methods:

• inorder_traversal() - Returns sorted sequence
• preorder_traversal() - Root-left-right order
• postorder_traversal() - Left-right-root order
• level_order_traversal() - Breadth-first traversal

Advanced Features:

• height() - Calculate tree height
• is_valid_bst() - Verify BST property
• print_tree() - ASCII visualization
• kth_smallest() - Find kth smallest element

🎓 Educational Examples

Student Grade Management:

grade_bst <- BST$new()
grades <- c(85, 92, 78, 96, 83, 88, 91, 79, 87, 94)

for (grade in grades) {
  grade_bst$insert(grade)
}

sorted_grades <- grade_bst$inorder_traversal()  # Automatic sorting
highest <- grade_bst$find_max()
median <- kth_smallest(grade_bst, ceiling(grade_bst$get_size()/2))

[Copilot]

Pull Request Overview

This PR implements a comprehensive Binary Search Tree (BST) data structure using R6 object-oriented programming, providing fundamental tree operations with optimal time complexity for educational and practical applications.

• Complete BST implementation with all core operations (insert, search, delete, traversals)
• R6 object-oriented design with proper encapsulation of private helper methods
• Educational examples demonstrating real-world applications like student grade management

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
data_structures/binary_search_tree.r	Complete BST implementation with nodes, tree operations, traversals, utility functions, and comprehensive test examples
DIRECTORY.md	Added Data Structures section with Binary Search Tree entry

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[Copilot]

Pull Request Overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 4 comments.

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[siriak]

Also add this data structure to DIRECTORY.md

[piyushkumar0707]

@siriak its already there

[siriak]

I don't see it and Copilot doesn't see it either

[piyushkumar0707]

@siriak I've just pushed the latest version to ensure the files are properly visible. The PR includes:

✅ Binary Search Tree Implementation (data_structures/binary_search_tree.r)

• Complete BST with R6 object-oriented approach
• All fundamental operations (insert, search, delete, traversals)
• 489 lines of well-documented code with comprehensive examples

✅ DIRECTORY.md Update

• Added new "Data Structures" section
• Proper entry for the BST implementation

The files should now be visible. Please let me know if you can see them now!

[Copilot]

Pull Request Overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

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