Solution for day 1 of AoC using C++

aoc_2019_1.cpp

std::string run(std::string input) override
{
  using namespace ranges;

  auto const not_empty  = [](auto&& l) { return !l.empty(); };
  auto const to_integer = [](auto&& l) { return std::stoi(l); };
  auto const calc_fuel  = [](auto&& mass) {
    auto fuel     = mass / 3 - 2;
    auto fuelMass = fuel;

    while (fuelMass / 3 - 2 > 0) {
      fuel += fuelMass / 3 - 2;
      fuelMass = fuelMass / 3 - 2;
    }

    return fuel;
  };

  auto lines  = extract_all_lines(input);
  auto masses = lines  | views::filter(not_empty) | views::transform(to_integer);
  auto fuel   = masses | views::transform(calc_fuel);
  auto total  = accumulate(fuel, 0);

  return std::to_string(total);
}