[CPP]Lucky_pair_reethikprasad.cpp

[reethikprasad]

• [x] Code is added in right directory(Folder).
• [x] Brief Description of Solution is given.
• [x] Time and Space Complexity is mentioned
• [x] Code is well indented.
• [x] Comments are clearly written wherever necessary
• [x] Code is successfully compiled and passes all test cases.

[anjali1903]

You should've created a new branch from the master branch.

[reethikprasad]

I actually created a new branch named Luckypair If still any changes please let me know