Polynomial

main.py

#include <iostream>
#include "polynomial.h"

using namespace std;

int main() {
    {
        cout << Polynomial {} << endl;
        cout << (Polynomial) {-3} << endl;
        cout << (Polynomial) {-2, 3} << endl;
        cout << (Polynomial) {5, 4, 7} << endl;
    }


    cout << endl;

    {
        vector<double> coefficients_p{4, 5, -1, 7, 0, 3};
        vector<double> coefficients_q{-3, 1, 0, -1, 0, 0, 4};
        Polynomial polynomial_p(coefficients_p);
        Polynomial polynomial_q(coefficients_q);
        Polynomial polynomial_r = polynomial_p + polynomial_q;

        cout << "P(x) = " << polynomial_p << endl;
        cout << "Degree of P(x) = " << polynomial_p.get_degree() << endl;
        cout << "P(5) = " << polynomial_p.calculate_result(5) << endl;
        cout << "Q(x) = " << polynomial_q << endl;
        cout << "R(x) = " << polynomial_r << endl;
    }

    return 0;
}

polynomial.cpp

#include "polynomial.h"

Polynomial::Polynomial() : coefficients({0}) {

}

Polynomial::Polynomial(double a0) : coefficients({a0}) {

}

Polynomial::Polynomial(double a0, double a1) : coefficients({a0, a1}) {

}

Polynomial::Polynomial(double a0, double a1, double a2) : coefficients({a0, a1, a2}) {

}

Polynomial::Polynomial(vector<double> &coefficients) : coefficients(coefficients) {

}

int Polynomial::get_degree() {
    return coefficients.size() - 1;
}

double Polynomial::calculate_result(double x) {
    double result = coefficients[coefficients.size() - 1];

    for (int i = coefficients.size() - 2; i >= 0; --i)
        result = result * x + coefficients[i];

    return result;
}

double Polynomial::get(int n) const {
    return coefficients.at(n);
}

Polynomial Polynomial::add(Polynomial &other) {
    vector<double> &bigger_vector = (this->coefficients.size() > other.coefficients.size())
                                    ? this->coefficients : other.coefficients;

    vector<double> &smaller_vector = (&bigger_vector == &this->coefficients)
                                     ? other.coefficients : this->coefficients;

    Polynomial result(bigger_vector);

    for (int i = 0; i < smaller_vector.size(); ++i)
        result.coefficients[i] += smaller_vector[i];

    return result;
}

double Polynomial::operator[](int n) const {
    return this->get(n);
}

Polynomial Polynomial::operator+(Polynomial  &other) {
    return add(other);
}

ostream &operator<<(ostream &stream, const Polynomial &polynomial) {
    for (int i = polynomial.coefficients.size() - 1; i >= 0; --i) {
        double coefficient = polynomial[i];
        if (coefficient != 0 || i == 0) {
            if (coefficient < 0 && i != 0)
                stream << '(' << coefficient << ')';
            else
                stream << coefficient;

            if (i > 0) {
                stream << " * x^" << i << " + ";
            }
        }
    }

    return stream;
}

polynomial.h

#ifndef POLYNOMIAL_H
#define POLYNOMIAL_H

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

class Polynomial {
private:
    vector<double> coefficients;

public:
    Polynomial();

    explicit Polynomial(double a0);

    Polynomial(double a0, double a1);

    Polynomial(double a0, double a1, double a2);

    Polynomial(vector<double> &coefficients);

    int get_degree();

    double calculate_result(double x);

    double get(int n) const;

    Polynomial add(Polynomial &other);

    double operator[](int n) const;

    Polynomial operator+(Polynomial &other);

    friend ostream &operator<<(ostream &stream, const Polynomial &polynomial);
};


#endif //POLYNOMIAL_H