temp.cpp

#include <iostream>
#include <vector>

typedef std::vector<int> Vector;
typedef std::vector<Vector> Matrix;

//  Сложение векторов
Vector operator + (const Vector & a, const Vector & b) {
    Vector c;
    for (int i = 0, s1 = (int)a.size(), s2 = (int)b.size(); i < s1 || i < s2; ++i)
        c.push_back((i < s1 ? a[i]:0) + (i < s2 ? b[i]:0));
    return c;
}

//  Умножение матриц
Matrix operator * (const Matrix & a, const Matrix & b) {

    Matrix c;
    for (int i = 0; i < (int)a.size(); ++i) {
        c.push_back(Vector());
        for (int j = 0; j < (int)b[0].size(); ++j) {
            c.back().push_back(0);
            for (int k = 0; k < (int)b.size(); ++k)
                c.back().back() += a[i][j] * b[j][k];
        }
    }
    return c;
}

int main() {
    setlocale(LC_ALL, "Russian");

    {   //  Сложение векторов
        auto c = Vector({1, 2, 3, 4}) + Vector({4, 5, 6});

        std::cout << "Сложение векторов:\n\t";

        for (auto & it : c)
            std::cout << it << "\t";

        std::cout << std::endl;
    }

    {   //  Умножение матриц
        auto c = Matrix({
                {1, 2, 3},
                {4, 5, 6},
                {7, 8, 9}
            }) * Matrix({
                {9, 8, 7},
                {6, 5, 4},
                {3, 2, 1}
            });

        std::cout << "Умножение матриц:\n";

        for (auto & row : c) {
            for (auto & it : row)
                std::cout << "\t" << it;
            std::cout << std::endl;
        }
    }

    return 0;
}