Add greedy algo solutions in cpp

[kinngddx]

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Description

Added a new folder C-Plus-Plus/greedy/ containing implementations of popular Greedy Algorithm problems in C++.
Each program is optimized, well-commented, and follows NeoAlgo’s contribution format.

📂 Problems Added

1. Activity Selection – Find maximum number of non-overlapping activities
2. Fractional Knapsack – Maximize total value using fractional items
3. Job Sequencing – Schedule jobs to maximize profit within deadlines
4. Huffman Encoding – Generate prefix codes based on character frequencies

Also updated the main C-Plus-Plus/README.md to include a link to this new folder.

Checklist

• I've read the contribution guidelines.
• I've checked the issue list before deciding what to submit.
• I've added my code in the correct folder (C-Plus-Plus/greedy/).
• I've edited the README.md and linked my code.
• My code is well-commented and runs without errors.
• I’ve ensured no plagiarism — all solutions are original.

Related Issues or Pull Requests

Fixes # (add your issue number here if you created one)

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