aocpp/2023/04.cpp

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

#include <boost/phoenix.hpp>
#include <boost/spirit/include/qi.hpp>

#include <doctest.h>

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

namespace {

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

struct Card
{
    unsigned long long id;
    std::vector<unsigned long long> mine;
    std::vector<unsigned long long> winners;
};

struct Grammar : public qi::grammar<std::string::const_iterator, std::vector<Card>(), ascii::space_type> {
  qi::rule<iterator_type, Card(), ascii::space_type> card;
  qi::rule<iterator_type, std::vector<Card>(), ascii::space_type> cards;

  Grammar() : base_type{cards} {
    using namespace qi::labels;
    cards = *card;
    card =
      "Card" >>   qi::ulong_long  [ phx::bind(&Card::id     , _val) = _1] >>
      ":"    >> (*qi::ulong_long) [ phx::bind(&Card::mine   , _val) = _1] >>
      "|"    >> (*qi::ulong_long) [ phx::bind(&Card::winners, _val) = _1];
  }
};

auto CountWins(std::vector<Card>& cards) -> std::vector<std::size_t>
{
  std::vector<std::size_t> result;
  result.reserve(cards.size());

  for (auto& card : cards)
  {
    std::sort(card.mine.begin(), card.mine.end());
    std::sort(card.winners.begin(), card.winners.end());
    auto const c = std::set_intersection(card.mine.begin(), card.mine.end(), card.winners.begin(), card.winners.end(), Counter<std::size_t>{});
    result.push_back(c);
  }

  return result;
}

auto Part1(std::vector<std::size_t> const& wins) -> std::uint64_t
{
  std::uint64_t result = 0;
  for (auto const win : wins)
  {
    if (win > 0)
    {
      result += std::uint64_t{1} << (win - 1);
    }
  }
  return result;
}

auto Part2(std::vector<std::size_t> const& wins) -> std::size_t
{
  std::vector<std::size_t> psums(wins.size() + 1);
  for (std::size_t i = wins.size(); i --> 0;)
  {
    psums[i] = 1 + 2 * psums[i + 1] - psums[i + 1 + wins[i]];
  }
  return psums.front();
}

} // namespace

TEST_SUITE("2023-04 examples") {
  TEST_CASE("example") {
    std::istringstream in {
R"(Card 1: 41 48 83 86 17 | 83 86  6 31 17  9 48 53
Card 2: 13 32 20 16 61 | 61 30 68 82 17 32 24 19
Card 3:  1 21 53 59 44 | 69 82 63 72 16 21 14  1
Card 4: 41 92 73 84 69 | 59 84 76 51 58  5 54 83
Card 5: 87 83 26 28 32 | 88 30 70 12 93 22 82 36
Card 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11
)"
    };
    auto input = aocpp::ParseGrammar_(Grammar{}, in);
    auto const wins = CountWins(input);
    CHECK(Part1(wins) == 13);
    CHECK(Part2(wins) == 30);
  }
}

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