#include <cstddef>
#include <array>
namespace detail {
constexpr std::size_t ipow(std::size_t base, std::size_t exponent) noexcept {
std::size_t p = 1;
while (exponent) {
if (exponent % 2 != 0) {
p *= base;
}
exponent /= 2;
base *= base;
}
return p;
}
}
template<std::size_t range, std::size_t sets>
constexpr std::array<std::array<std::size_t, sets>, detail::ipow(range, sets)>
cartesian_product() noexcept {
constexpr std::size_t size = detail::ipow(range, sets);
std::array<std::array<std::size_t, sets>, size> result{};
for (std::size_t i = 0; i < size; ++i) {
std::size_t place = size;
for (std::size_t j = 0; j < sets; ++j) {
place /= range;
result[i][j] = (i / place) % range;
}
}
return result;
}
#include <iostream>
int main() {
constexpr auto crt = cartesian_product<4, 6>();
for (auto [a, b, c, d, e, f] : crt) {
std::cout << a << ' ' << b << ' ' << c << ' ' << d << ' ' << e << ' ' << f << '\n';
}
}
