#include <stdio.h>
 
class Feature
{
public:
    enum FeatureType {eUnknown, eCircle, eTriangle, eSquare};
 
    Feature() : type(eUnknown), points(0) {    }
 
    ~Feature()
    {
        if (points)
            delete points;
    }
 
    bool isValid() 
    {
        return type != eUnknown;
    }
 
    bool read(FILE* file)
    {        
        if (fread(&type, sizeof(FeatureType), 1, file) != sizeof(FeatureType))
            return false;
        short n = 0;
        switch (type) 
        {
        case eCircle: n = 3; break;
        case eTriangle:    n = 6; break;
        case eSquare: n = 8; break;
        default: type = eUnknown; return false;
        }
        points = new double[n];
        if (!points)
            return false;
        return fread(&points, sizeof(double), n, file) == n*sizeof(double);
    }
    void draw()
    {
        switch (type)
        {
        case eCircle: drawCircle(points[0], points[1], points[2]); break;
        case eTriangle:    drawPoligon(points, 6); break;
        case eSquare: drawPoligon(points, 8); break;
        }
    }
 
protected:
    void drawCircle(double centerX, double centerY, double radius);
    void drawPoligon(double* points, int size);
 
    double* points;
    FeatureType type;        
};
 
int main(int argc, char* argv[])
{
    Feature feature;
    FILE* file = fopen("features.dat", "r");
    feature.read(file);
    if (!feature.isValid())
        return 1;
    return 0;
}

double sum1(std::vector<double>& v)
{    
    if (v.empty()) {
        return 0.0;
    }
    for(size_t i = 0; i < v.size() - 1; ++i) {
        std::sort(v.begin()+i, v.end());
        v[i+1] += v[i];
    }
    return v.back();
}
 
double sum2(std::vector<double>& v)
{    
    if (v.empty()) {
        return 0.0;
    }
    for(size_t i = 0; i < v.size() - 1; ++i) {
        std::partial_sort(v.begin() + i, v.begin() + i + 2, v.end());
        v[i+1] += v[i];
    }
    return v.back();
}
 
double sum3(std::vector<double>& v)
{    
    std::multiset<double> set(v.begin(), v.end());
    while (set.size() > 1) {
        std::multiset<double>::const_iterator itA = set.begin();
        std::multiset<double>::const_iterator itB = ++set.begin();
        double c = *itA + *itB;
        set.erase(itA, itB);        
        set.insert(c);
    }
    return !set.empty() ? *set.begin() 
                        : 0.0;
}