Polynomial.cpp

#include <iostream>
#include <vector>
#include <cmath>

class Polynomial {
private:
	int base, var;
	std::vector<int> constants;
	char signature;
public:
	Polynomial(char sig = 'f', int base = 0, int var = 1) {
		this->base = base;
		this->var = var;
		signature = sig;
		constants.resize(base + 1);
	}

	~Polynomial() {}

	float calc() {
		float sum = 0;
		for (int i = base, j = 0; i >= 0, j < base + 1; i--, j++) {
			if (i > 0) {
				sum += static_cast<float>(constants.at(j) * pow(var, i));
				continue;
			}
			sum += constants.at(base);
		}
		return sum;
	}

	friend std::istream &operator>>(std::istream &in, Polynomial &poly) {
		for (auto i = 0; i < poly.constants.size(); i++)
			in >> poly.constants.at(i);
		return in;
	}

	friend std::ostream &operator<<(std::ostream &out, const Polynomial &poly) {
		out << poly.signature << "(x)=";
		for (int i = poly.base, j = 0; i >= 0, j < poly.base + 1; i--, j++) {
			if (i > 1) {
				out << poly.constants.at(j) << "x^" << i << "+";
				continue;
			}
			else if (i == 1) {
				out << poly.constants.at(poly.base - 1) << "x+";
				continue;
			}
			out << poly.constants.at(poly.base);
		}
		out << '\n';
		return out;
	}

	Polynomial operator+(const Polynomial &poly) {
		Polynomial res;
		int size;

		if (this->constants.size() > poly.constants.size()) {
			size = static_cast<int>(this->constants.size());
			res.base = this->base;
			res.var = this->var;
			res.constants.at(0) = this->constants.at(0);
		}
		else if (this->constants.size() < poly.constants.size()) {
			size = static_cast<int>(poly.constants.size());
			res.base = poly.base;
			res.var = poly.var;
			res.constants.at(0) = poly.constants.at(0);
		}
		else {
			size = static_cast<int>(poly.constants.size());
			res.base = poly.base;
			res.var = poly.var;
		}

		res.constants.resize(size);

		if (size > poly.constants.size())
			for (int i = 1; i < size; i++)
				res.constants.at(i) = this->constants.at(i) + poly.constants.at(i - 1);
		else if (size > this->constants.size())
			for (int i = 1; i < size; i++)
				res.constants.at(i) = this->constants.at(i - 1) + poly.constants.at(i);
		else
			for (int i = 0; i < size; i++)
				res.constants.at(i) = this->constants.at(i) + poly.constants.at(i);

		return res;
	}

	Polynomial operator-(const Polynomial &poly) {
		Polynomial res;
		int size;

		if (this->constants.size() > poly.constants.size()) {
			size = static_cast<int>(this->constants.size());
			res.base = this->base;
			res.var = this->var;
			res.constants.at(0) = this->constants.at(0);
		}
		else if (this->constants.size() < poly.constants.size()) {
			size = static_cast<int>(poly.constants.size());
			res.base = poly.base;
			res.var = poly.var;
			res.constants.at(0) = poly.constants.at(0);
		}
		else {
			size = static_cast<int>(poly.constants.size());
			res.base = poly.base;
			res.var = poly.var;
		}

		res.constants.resize(size);

		if (size > poly.constants.size())
			for (int i = 1; i < size; i++)
				res.constants.at(i) = this->constants.at(i) - poly.constants.at(i - 1);
		else if (size > this->constants.size())
			for (int i = 1; i < size; i++)
				res.constants.at(i) = this->constants.at(i - 1) - poly.constants.at(i);
		else
			for (int i = 0; i < size; i++)
				res.constants.at(i) = this->constants.at(i) - poly.constants.at(i);

		return res;
	}

	void operator=(const Polynomial &res) {
		this->base = res.base;
		this->var = res.var;
		this->constants.resize(res.constants.size());

		for (auto i = 0; i < res.constants.size(); i++)
			this->constants.at(i) = res.constants.at(i);
	}
};

int main() {
	Polynomial f('f', 3, 1), g('g', 2, 1), h('h');
	std::cout << "Nhap f(x):\n";
	std::cin >> f;
	std::cout << "Nhap g(x):\n";
	std::cin >> g;
	std::cout << f;
	std::cout << g;

	h = f + g;
	std::cout << h;
	return 0;
}

Nhap f(x):
3 4 5 1

Nhap g(x):
3 4 2

f(x)=3x^3+4x^2+5x+1
g(x)=3x^2+4x+2
h(x)=3x^3+7x^2+9x+3