acm-code-snippets

They are snippets used in algorithm contest.
Most of them used class definition (but not fully object-oriented) rather than C programming language's statement in order to facilitate using them in contest and avoid naming conflict and too large variant scope.
The majority of the code is based on GNU C++ standard library, which usually requires

#include <bits/stdc++.h>
using namespace std;

Some of them may use C++ 11 features.

If you want to include them in your project, you may need to do some modification. For example, add

#ifndef SOME_HEADER_H
#define SOME_HEADER_H
// content
#endif // SOME_HEADER_H

and deal with namespace problems.