Cosmos: Stop Using <bits/stdc++.h> for Portability

[arnavb]

This is a(n):

• [ ] New algorithm
• [ ] Update to an existing algorithm
• [x] Error
• [x] Proposal to the Repository

Details:

I was googling up about the header file <bits/stdc++.h>, and found that it is considered generally bad practice to use it, because it is nonportable (It only works on g++, not MSVC or XCode), and it increases compilation time and runtime (linking all the implementations) (since it is including everything in the standard library).

1. (Source)
2. (Source)

Thus, I vote not using this header file and instead directly including files from the standard.

[tbhaxor]

@arnavb yes its a bad practice coz it binds all header files and std library

[arnavb]

I will open a PR soon that will attempt to solve this. Also, I think we should mandate any new PRs to NOT use the header file, but to directly include the STL files.