want to add more cpp programs

[Ananyajain2004]

I want to add programs of data structures like tree ,stack, graph , binary search sliding window for placements. @yesiamrajeev please assign this issue to me under hacktoberfest 2024.

Please mark the hacktoberfest and hacktoberfest-accepted labels upon approving and merging the request.

[yesiamrajeev]

Sure go on!