aocpp/2019/13.cpp

#include <iostream>
#include <stdexcept>
#include <utility>
#include <tuple>
#include <set>

#include <aocpp/Startup.hpp>
#include <aocpp/Coord.hpp>
#include <intcode/intcode.hpp>
using namespace aocpp;
using namespace intcode;

namespace {

auto Compute1(Machine machine)
  -> std::size_t {
  std::set<Coord> screen;

  Run(machine,
    []() -> ValueType { throw std::runtime_error{"unexpected input request"}; },
    [&](auto x) {
      auto y = StepOutput(machine);
      auto v = StepOutput(machine);
      if (2 == v) { screen.insert({x,y}); } else { screen.erase({x,y}); }
    });
  return screen.size();
}

auto Compute2(Machine machine) {
  ValueType score {0};
  ValueType paddleX {0};
  ValueType ballX {0};

  machine.At(0) = 2;

  Run(machine,
    [&]() {
      return paddleX < ballX ? 1 : paddleX > ballX ? -1 : 0;
    },
    [&](auto x) {
      auto y = StepOutput(machine);
      auto v = StepOutput(machine);

      if (-1 == x && 0 == y) {
        score = v;
      } else {
        switch (v) {
          case 3: // paddle
            paddleX = x;
            break;
          case 4: // ball
            ballX = x;
            break;
        }
      }
    });
  return score;
}

} // namespace

auto Main(std::istream & in, std::ostream & out) -> void
{
  auto machine = Machine{ParseStream(in)};
  out << "Part 1: " << Compute1(machine) << std::endl;
  out << "Part 2: " << Compute2(std::move(machine)) << std::endl;
}