Added solution of Nqueen problem algo using backtracking

[Tirth22]

Description

The given code gives the coordinates of cell in chess board where the N queens can be placed without any collision. The approach used to solve given problem is backtracking

Fixes #(issue_no)

Replace issue_no with the issue number which is fixed in this PR

Type of change

Please delete options that are not relevant.

• [ ] New feature (non-breaking change which adds functionality)

Checklist:

• [ ] My code follows the style guidelines(Clean Code) of this project
• [ ] I have performed a self-review of my own code
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] I have created a helpful and easy to understand README.md
• [ ] I have made corresponding changes to the documentation
• [ ] My changes generate no new warnings
• [ ] I have added tests/screenshots(if any) that prove my fix is effective or that my feature works

[Ayush7614]

DS ALGO PROJECTS ARE NOT COUNTED FOR HACKTOBERFEST21 so i will close this PR