Fix sorting algorithm bugs and improve metrics tracking

[shubhpatel9]

Summary

This PR fixes critical bugs in the sorting algorithm implementations and improves operation metrics tracking for more accurate efficiency analysis. The changes address incorrect swap operations, incomplete bubble sort for lists, and metrics reset issues in quicksort.

Key Changes

Bubble Sort (vector<int>)

• Fixed swap operation: Replaced arithmetic swap (vec[i] += vec[i+1]; ...) with std::swap(vec[i], vec[i+1]) for correctness and clarity
• Corrected metrics: Changed accesses += 3 to accesses += 2 to accurately count only the two write operations (reads already counted in comparison)

Bubble Sort (list<int>)

• Implemented proper bubble sort: Replaced incomplete selection-sort-style nested loop with correct bubble sort using iterator-based swaps and early-exit optimization
• Fixed return value: Changed return 0 to return true to indicate successful completion
• Improved metrics tracking: Properly count reads and writes for list element comparisons and swaps

Insertion Sort (vector<int>)

• Refined metrics tracking: Separated read and write operations in the while loop for more granular operation counting
• Improved loop logic: Changed condition from while (i >= 0 && vec[i] > key) to separate the boundary check and comparison for clearer metrics attribution

Merge Sort (vector<int>)

• Added metrics reset: Initialize metrics.accesses and metrics.comparisons to 0 at the start of merge_sort() to ensure clean state before recursive calls

Quicksort (vector<int>)

• Fixed critical swap bug: Changed swap(i, j) to swap(vec[i], vec[j]) to actually swap array elements instead of just swapping index variables
• Refactored metrics handling: Extracted recursive logic into quicksort_helper() that does NOT reset metrics, allowing totals to accumulate across all recursive calls. Public quicksort() entry point resets metrics once before delegating to helper
• Added swap metrics: Count 2 accesses for each element swap operation
• Code cleanup: Fixed typos and improved comments

Documentation

• Added CLAUDE.md: Comprehensive project documentation including repository structure, source file roles, implemented algorithms, known issues, build instructions, and development workflow

Notable Implementation Details

• Metrics now accurately distinguish between read and write operations
• Quicksort metrics now correctly accumulate across all recursive frames instead of only reporting the final frame
• All sorting implementations maintain consistent SortMetrics tracking for fair algorithm comparison
• Both root-level and sorting/ directory files are kept in sync with identical changes

https://claude.ai/code/session_01Bq4tyZTqt1W7VNi9hLe6Fk