Add CPP programs and update contributor file

[raza-khan0108]

Description

This pull request adds a comprehensive CPP folder containing 60+ C++ programs covering essential data structures and algorithms, along with updates to project documentation.

What's Included

• Data Structures: Arrays, Linked Lists (single, circular, doubly), Stacks, Queues
• Graph Algorithms: BFS, DFS, Prim's algorithm
• Sorting Techniques: Bubble, merge, quick, insertion, selection, and counting sort
• Tree Operations: AVL trees, Binary Search Trees with insert/delete
• Recursion Examples: Factorial, Fibonacci, nCr, power calculations
• Advanced Topics: Hash-based solutions and dynamic programming

Files Modified

• Updated CONTRIBUTOR.md

Structure

CPP/ folder organized by topic with dedicated subdirectories for Graphs, Sorting Techniques, Trees, and individual files for array operations, recursion, and linked lists.

Benefits

• Complete learning resource for C++ fundamentals
• Well-organized for easy navigation
• Useful for competitive programming practice
• Educational reference material

Testing

All new files are additive with no breaking changes.