#include <vector>
#include <chrono>
#include <iostream>

// Funktion erzeugt zwei Matrizen A und B der Größe n x n mit Zufallswerten
void generateRandomMatrices(int n,
                            std::vector<std::vector<double>>& A,
                            std::vector<std::vector<double>>& B,
                            double min_val = 0.0,
                            double max_val = 10.0)
{
    // Zufallsgenerator initialisieren
    std::srand(static_cast<unsigned int>(std::time(nullptr)));

    A.resize(n, std::vector<double>(n));
    B.resize(n, std::vector<double>(n));

    for (int i = 0; i < n; ++i)
        for (int j = 0; j < n; ++j)
        {
            double r1 = static_cast<double>(std::rand()) / RAND_MAX; // 0..1
            double r2 = static_cast<double>(std::rand()) / RAND_MAX; // 0..1
            A[i][j] = min_val + r1 * (max_val - min_val);
            B[i][j] = min_val + r2 * (max_val - min_val);
        }
}

// Matrizenmultiplikation
std::vector<std::vector<double>> matmul(const std::vector<std::vector<double>>& A,
    const std::vector<std::vector<double>>& B)
{
    int n = A.size();
    int m = B[0].size();
    int p = B.size();

    if (A[0].size() != B.size())
        throw std::runtime_error("Matrixgrößen passen nicht.");

    std::vector<std::vector<double>> C(n, std::vector<double>(m, 0.0));

    for (int i = 0; i < n; ++i)
        for (int j = 0; j < m; ++j)
            for (int k = 0; k < p; ++k)
                C[i][j] += A[i][k] * B[k][j];

    return C;
}

int main()
{
    int N = 500; // z.B. 500x500
    std::vector<std::vector<double>> A, B;

    auto start = std::chrono::steady_clock::now();

    generateRandomMatrices(N, A, B);
    auto C_serial = matmul(A, B);

    auto end = std::chrono::steady_clock::now();
    std::chrono::duration<double> diff = end - start;
    std::cout << "Took: " << diff.count() << "s\n";

    return 0;
}
//
// Created by Anke Bidlingmaier on 15.12.25.