aocpp/2023/02.cpp

#include <algorithm>
#include <cstdint>
#include <iostream>
#include <sstream>
#include <string>
#include <tuple>
#include <unordered_map>
#include <vector>

#include <boost/fusion/adapted/std_tuple.hpp>
#include <boost/phoenix.hpp>
#include <boost/spirit/include/qi.hpp>

#include <doctest.h>

#include <aocpp/Parsing.hpp>
#include <aocpp/Startup.hpp>

namespace {

namespace qi = boost::spirit::qi;
namespace phx = boost::phoenix;
namespace ascii = boost::spirit::ascii;

struct Game
{
    unsigned long long game_id;
    std::vector<std::vector<std::tuple<unsigned long long, std::string>>> rounds;
};

struct Grammar : public qi::grammar<std::string::const_iterator, std::vector<Game>(), ascii::space_type> {
  qi::rule<iterator_type, Game(), ascii::space_type> game;
  qi::rule<iterator_type, std::vector<Game>(), ascii::space_type> games;
  qi::rule<iterator_type, std::tuple<unsigned long long, std::string>(), ascii::space_type> entry;

  Grammar() : base_type{games} {
    using namespace qi::labels;
    games = *game;
    game =
      "Game" >> qi::ulong_long [ phx::bind(&Game::game_id, _val) = _1] >> ":" >>
      (entry % "," % ";") [ phx::bind(&Game::rounds, _val) = _1];
    entry = qi::ulong_long >> qi::lexeme [ qi::as_string[+qi::alpha] ];
  }
};

auto Part1(std::vector<Game> const& input) -> unsigned long long
{
  static auto const limits = std::unordered_map<std::string, unsigned long long>{
    {"red", 12},
    {"green", 13},
    {"blue", 14},
  };

  unsigned long long result = 0;
  for (auto const& game : input)
  {
    auto const good = std::all_of(game.rounds.begin(), game.rounds.end(), [](auto const& round)
    {
      return std::all_of(round.begin(), round.end(), [](auto const& entry)
      {
        auto const limit = limits.find(std::get<1>(entry));
        return limit != limits.end() && limit->second >= std::get<0>(entry);
      });
    });
    if (good)
    {
      result += game.game_id;
    }
  }
  return result;
}

auto Part2(std::vector<Game> const& input) -> unsigned long long
{
  unsigned long long result = 0;
  for (auto const& game : input)
  {
    std::unordered_map<std::string, unsigned long long> maxes;
    for (auto const& round : game.rounds) {
      for (auto const& [count, color] : round)
      {
        auto& entry = maxes[color];
        entry = std::max(entry, count);
      }
    }

    result += std::transform_reduce(
      maxes.begin(), maxes.end(),
      1ULL, std::multiplies{}, [](auto& kv) { return kv.second; });
  }

  return result;
}

} // namespace

TEST_SUITE("2023-02 examples") {
  TEST_CASE("example") {
    std::istringstream in {
R"(Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green
Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue
Game 3: 8 green, 6 blue, 20 red; 5 blue, 4 red, 13 green; 5 green, 1 red
Game 4: 1 green, 3 red, 6 blue; 3 green, 6 red; 3 green, 15 blue, 14 red
Game 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green
)"
    };
    auto const input = aocpp::ParseGrammar_(Grammar{}, in);
    CHECK(Part1(input) ==     8);
    CHECK(Part2(input) == 2'286);
  }
}

auto Main(std::istream & in, std::ostream & out) -> void
{
  auto const input = aocpp::ParseGrammar_(Grammar{}, in);
  out << "Part 1: " << Part1(input) << std::endl;
  out << "Part 2: " << Part2(input) << std::endl;
}