This code calculates at compile time the least number of coins needed to pay change. It's not very fast and might not work for every single case, but it gave the same result as this website for every reasonable value I tested. Also doubles as a compiler torturer.
This requires C++20 and was tested with clang and g++ using -Wpedantic.
constexpr int value_as_cents{239};
constexpr std::array coins{1, 5, 10, 25};
std::cout << Change<value_as_cents, coins>() << std::endl;14