Найти сумму минимальных элементов, расположенных в четных столбцах массивов

#include <iostream>
 
using namespace std;
 
const int N = 6;
 
void init_matrix(int matrix[N][N], int size)
{
    for (int i = 0; i < size; i++)
        for (int j = 0; j < size; j++)
            matrix[i][j] = std::rand() % 9 + 1;
}
 
int find_min_sum(int matrix[N][N], int size)
{
    int sum = 0;
    for (int col = 0; col < size; col++)
    {
        int min_i = -1;
        for (int row = 0; row < size && !(col % 2); row++)
            min_i = (matrix[row][col] < matrix[min_i][col] || min_i == -1) ? row : min_i;
 
        if (!(col % 2)) sum += matrix[min_i][col];
    }
 
    return sum;
}
 
void print_matrix(int matrix[N][N], int size)
{
    for (int i = 0; i < size; i++)
    {
        for (int j = 0; j < size; j++)
            std::cout << matrix[i][j] << " ";
 
        std::cout << endl;
    }
 
    std::cout << endl << endl;
}
 
int main()
{
    int a[N][N] = { 0 }, b[N][N] = { 0 }, c[N][N] = { 0 }, d[N][N] = { 0 };
 
    init_matrix(a, N); std::cout << "a[][] = " << endl; print_matrix(a, N);
    init_matrix(b, N); std::cout << "b[][] = " << endl; print_matrix(b, N);
    init_matrix(c, N); std::cout << "c[][] = " << endl; print_matrix(c, N);
    init_matrix(d, N); std::cout << "d[][] = " << endl; print_matrix(d, N);
 
    std::cout << "matrix a sum = " << find_min_sum(a, N) << endl;
    std::cout << "matrix b sum = " << find_min_sum(b, N) << endl;
    std::cout << "matrix c sum = " << find_min_sum(c, N) << endl;
    std::cout << "matrix d sum = " << find_min_sum(d, N) << endl;
 
    std::cin.get();
}