#include <iostream>
#include <vector>

using namespace std;

vector<vector<double>> transpose(const vector<vector<double>>& matrix){
    unsigned short rows = matrix.size();
    unsigned short cols = matrix[0].size();

    vector<vector<double>> transposed(cols, vector<double>(rows));

    for(unsigned char i = 0; i < rows; ++i){
        for(char j = 0; j < cols; ++j){
            transposed[j][i] = matrix[i][j];
        }
    }

    return transposed;
}

vector<vector<double>> dot_product(const vector<vector<double>>& inputs, const vector<vector<double>>& weights){
    short input_rows = inputs.size();
    short input_cols = inputs[0].size();
    short weight_rows = weights.size();
    short weight_cols = weights[0].size();

    vector<vector<double>> transposed_weights = transpose(weights);

    if(input_cols != transposed_weights.size()){
        printf("Shape error\n");
        exit(1);
    }

    vector<vector<double>> result(input_rows, vector<double>(weight_cols, 0.0));

    for(char i = 0; i < input_rows; ++i){
        for(char j = 0; j < weight_rows; ++j){
            for(char k = 0; k < input_cols; ++k){
                if(k < input_cols && j < weight_cols){
                    result[i][j] += inputs[i][k] * transposed_weights [j][k];
                }
            }
        }
    }

    return result;
}

int main(){
    vector<vector<double>> inputs = {
                     {1., 2., 3., 2.5},
                     {2. , 5. , -1., 2.},
                     {-1.5 , 2.7 , 3.3, -0.8}
                     };
    vector<vector<double>> weights = {
                    {0.2, 0.8, -0.5, 1.},
                    {0.5, -0.91, 0.26, -0.5},
                    {-0.26, -0.27, 0.17, 0.87}
                    };
    vector<double> biases = {2, 3, 0.5};
    vector<vector<double>> result = dot_product(inputs, weights);
    for(char i = 0; i < result.size(); ++i){
        for(char j = 0; j < result.size(); ++j){
            result[i][j] += biases[j];
        }
    }
    printf("Should be right: %f \n", result[2][3]);
    return 0;
}