Sa se implementeze clasele Cerc si Dreptunghi derivate din FiguraGeometrica. Clasa FiguraGeometrica va fi definita ca si clasa abstractă având declarată metoda getPerimetru() ca funcție virtuală pură.

#include <math.h>
#include <conio.h>
#include <iostream>
#define M_PI 3.14159265
using namespace std;

class Punct {
      float x,y;
   public:
      Punct(float x = 0, float y = 0);          
      void setX(float x);
      float getX();
      void setY(float y);
      float getY();
      friend ostream & operator << (ostream &out, Punct &p);
};

Punct:: Punct(float x, float y){
      this->x = x; this->y = y; 
}

void Punct::setX(float x){
      this->x = x;
}

float Punct::getX(){
      return x;
}

void Punct::setY(float y){
      this->y = y;
}

float Punct::getY(){
      return y;
}

ostream & operator << (ostream &out, Punct &p){
    out<<"("<<p.x<<","<<p.y<<")";
    return out;
}
class FiguraGeometrica {
      public:         
         virtual float getPerimetrul() = 0;
         virtual void print();

};

void FiguraGeometrica::print(){
     cout<<"Figura Geometrica Oarecare"<<endl;
}

class Cerc: public FiguraGeometrica {
        Punct centru;
        float raza;
      public:       
        Cerc (Punct c, float r);  
        float getPerimetrul();   
        void print();
};
Cerc::Cerc(Punct c, float r):centru(c), raza(r){
}

float Cerc::getPerimetrul() {
      return 2*M_PI*raza;
}
void Cerc::print(){
     cout<<"Cerc ("<<centru<<","<<raza<<")"<<endl;
}


class Dreptunghi: public FiguraGeometrica {
      Punct colt_s_s; //colt stanga sus
      Punct colt_d_j; //colt dreapta jos
     public:
      Dreptunghi (Punct c_s_s, Punct c_d_j); 
      float getPerimetrul();
      void print();      
};      

Dreptunghi::Dreptunghi(Punct c_s_s, Punct c_d_j): colt_s_s(c_s_s), colt_d_j(c_d_j){
}
float Dreptunghi::getPerimetrul() {
      return 2*(colt_d_j.getX()-colt_s_s.getX())+2*(colt_s_s.getY()-colt_d_j.getY());
}
void Dreptunghi::print(){
     cout<<"Dreptunghi ["<<colt_s_s<<","<<colt_d_j<<"]"<<endl;;
}

int main(){    
    FiguraGeometrica *f[]={new Cerc(Punct(0,0),1), new Dreptunghi(Punct(0,1),Punct(2,0))}; 
    for(int i=0;i<2;i++){
         f[i]->print();
         cout<<"Perimetrul = "<<f[i]->getPerimetrul()<<endl;   
    }
    getch();
}      

Realizati o clasa abstracta pentru rezolvarea problemelor ce utilizeaza metoda backtracking. Sa se utilizeze aceasta clasa pentru rezolvarea problemei damelor.

#include <math.h>
#include <conio.h>
#include <iostream>

using namespace std;

class Dame;
class Backtracking{
   protected:
      int x[100];
      int k;
   public:
   void solve();
   virtual void initLevel() = 0;
   virtual  int succesor() = 0;
   virtual  int  validate() const=0;
   virtual  int  testSolution() const=0;
   virtual  void printSolution() const=0;
};

void Backtracking::solve() {
      int is,iv=0;
      k=1;
      initLevel();
      while (k>0){
         do{
            is=succesor();
            if (is)
               iv=validate();
         } while (!((!is)||((is)&&(iv))));
         if(is)
            if(testSolution()) printSolution();
            else{
               k++;
               initLevel();
            }
            else k--;
      }
}


class Dame: public Backtracking{
   int table;
public:
   Dame(int n);
   void initLevel();
   int succesor();
   int validate() const;
   int testSolution() const;
   void printSolution() const;
};

Dame::Dame(int n){
 table=n;
 for (int i=1;i<=table;i++)
   x[i]=0;
}
void Dame::initLevel() {
      x[k]=0;
   }

int Dame::succesor() {
      if (x[k]<table){
         x[k]+=1;
         return 1;
      } else {
       return 0;
      }
   }

int Dame::validate() const{
      for (int i=1;i<k;i++)
         if ((x[k]==x[i])||(abs(x[k]-x[i])==abs(k-i)))
           return 0;
      return 1;
}
int Dame::testSolution() const{
      if (k==table) return 1;
      return 0;
   }

void Dame::printSolution() const{
      for (int i=1;i<=table;i++)
         cout<<x[i]<<" ";
      cout<<"\n";
}

int main (){
   Dame *d=new Dame(4);

   d->solve();
   getch();
   return 0;
}