text: #ifndef PARTICLES_HDR
  #define PARTICLES_HDR
  
  #include <random>
  #include <vector>
  #include "params.h"
  #include "statistics.h"
  #include "distribution.h"
  
  class Particles {
      protected:
          std::vector<int> _positions;
          std::mt19937_64 _engine;
          std::uniform_int_distribution<int> _distr;
      public:
          Particles(const Params& params);
          virtual ~Particles() {};
          auto get_nr_particles() const { return _positions.size(); };
          virtual void move();
          virtual double get_collision_fraction() const { return 0.0; };
          Statistics get_statistics() const;
          Distribution get_distribution() const;
  };
  
  #endif
  