#include <iostream>
#include <vector>

template <typename T>
bool increase(const std::vector<std::vector<T>>& v, std::vector<std::size_t>& it)
{
    for (std::size_t i = 0, size = it.size(); i != size; ++i) {
        const std::size_t index = size - 1 - i;
        ++it[index];
        if (it[index] == v[index].size()) {
            it[index] = 0;
        } else {
            return true;
        }
    }
    return false;
}

template <typename T>
void do_job(const std::vector<std::vector<T>>& v, std::vector<std::size_t>& it)
{
    for (std::size_t i = 0, size = v.size(); i != size; ++i) {
        std::cout << v[i][it[i]] << " ";
    }
    std::cout << std::endl;
}

template <typename T>
void iterate(const std::vector<std::vector<T>>& v)
{
    std::vector<std::size_t> it(v.size(), 0);

    do {
        do_job(v, it);
    } while (increase(v, it));
}

int main(int argc, char *argv[])
{
    std::vector<std::vector<int>> v = {
        {0, 1, 2, 3, 4, 5},
        {0, 1, 2, 3, 4, 5},
        {0, 1, 2, 3, 4, 5}
    };

    iterate(v);
    return 0;
}