polygon.h

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#pragma once
 
#include <iostream>
#include <vector>
#include <cmath>
 
class Point2D
{
  public:
    Point2D() : _x(0.0f), _y(0.0f) {}
 
    Point2D(float x, float y) : _x(x), _y(y) {}
 
    float GetX() const {return _x;}
 
    float GetY() const {return _y;}
 
private:
    float _x; 
    float _y; 
};
 
std::ostream& operator<<(std::ostream& s, const Point2D& rhs);
 
// float dist(const Point2D& a, const Point2D& b);
inline float dist(const Point2D& a, const Point2D& b)
{
    return  std::sqrt( std::pow(a.GetX()-b.GetX(),2) + std::pow(a.GetY()-b.GetY(),2) );
}
 
//------------------------------------------
 
class Polygon_old
{
  public:
    Polygon_old(int n);
    void append(const Point2D& a) { _v.push_back(a); }
    int number() const { return _v.size(); }
    float perimeter() const;
    bool operator<(const Polygon_old& rhs) const { return perimeter() < rhs.perimeter(); }
 
  private:
    std::vector<Point2D> _v;
};
 
//------------------------------------------
class Polygon
{
  public:
    Polygon(int n);
 
    void append(const Point2D& a) { _v.push_back(a); _peri=-1.0f; }
 
    int number() const { return _v.size(); }
 
    float perimeter() const;
 
    bool operator<(const Polygon& rhs) const { return perimeter() < rhs.perimeter(); }
 
  private:
    std::vector<Point2D> _v;     
    mutable float   _peri;  
};