Create Longest Zig-Zag Subsequence.md

[Nelcy17]

Created a Longest Zig-Zag-Subsequence problem which is solved using Dynamic Programming Method.

📥 Pull Request

Fixes #1346 (issue number)

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[github-actions]

👋 Hi @Nelcy17! Thank you for submitting your first pull request to the Algo project. Great job on the contribution! 🎉 We appreciate your efforts, and our team will review it soon. If you have any questions, feel free to ask. Keep up the great work! 🚀

[github-actions]

🎉 Great job, @Nelcy17! Thank you for submitting your pull request. We appreciate your contribution, and our team will review it shortly.

[github-actions]

⚡️ Lighthouse Report for the Deploy Preview of this PR 🚀

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/algo/blog	🟡 68	🟢 92	🟢 96	🟡 86	📄

[ajay-dhangar]

Done