Diameter of Binary Tree added

[neha030]

I have added the C++ code for Diameter of a Binary Tree
Please review my code.

[neha030]

Fixes #47

[nimisha-yadav]

Hey @neha030! As per the contribution guidelines, can you describe your algorithm in brief at the starting of your code? Also, your code uses O(n^2) complexity, can you optimize it?

[neha030]

Hey @neha030! As per the contribution guidelines, can you describe your algorithm in brief at the starting of your code? Also, your code uses O(n^2) complexity, can you optimize it?

Ok I will add the Description of the algorithm and try to optimize it

[v-vanisha]

Hey @neha030, you need to include a minimum of 2 test cases for your code according to the guidelines. Kindly do the same.