#include <vector>
#include <iostream>
using std::size_t;

std::vector<int> get_column(std::vector<std::vector<int>> input, int index){
    std::vector<int> result;
    for(int i = 0; i<input.size(); i++){
        result.push_back(input[i][index]);
    }
    return result;
}

int multiply(std::vector<int> first, std::vector<int> second){
    int result = 0;
    for(int i = 0; i<first.size(); i++){
        result += first[i] * second[i];
    }
    return result;
}

std::vector<std::vector<int>> matrix_multiplication(std::vector<std::vector<int>> &a, std::vector<std::vector<int>> &b, size_t n){
    std::vector<std::vector<int>> result;
    std::vector<int> row;
    for(int i=0; i<n;i++){
        for(int j=0; j<n; j++){
            row.push_back(
                multiply(a[i], get_column(b, j))
            );
        }
        result.push_back(row);
        row = {};
    }
    return result;
}


int main(){
    std::vector<std::vector<int>> test1 = {{1,2},{3,4}};
    std::vector<std::vector<int>> test2 = {{1,2},{3,4}};
    std::vector<std::vector<int>> result = matrix_multiplication(test1, test2, 2);
    std::cout << result[1][1];
}