aocpp/2019/21.cpp

#include <algorithm>
#include <iostream>
#include <map>
#include <set>
#include <tuple>
#include <utility>
#include <vector>
#include <sstream>

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

using namespace aocpp;
using namespace intcode;

namespace {

auto OffByOne (
  std::string const& x,
  std::string const& y
) -> std::size_t
{
  auto const [it_x, it_y] = std::mismatch(x.begin(), x.end(), y.begin());
  return
     (it_x != x.end() &&
      *it_x == '.' &&
      *it_y == '#' &&
      std::equal(it_x+1, x.end(), it_y+1))
    ? std::distance(x.begin(), it_x)
    : std::string::npos;
}

auto CountOnes(std::string const& key) -> std::size_t {
  return std::count_if(key.begin(), key.end(), [](auto c) { return c == '#'; });
}

auto QuineMcCluskey(
  bool const polarity,
  std::size_t const vars,
  std::map<std::string, bool> const& behavior
) {
  std::set<std::string> done;
  std::vector<std::set<std::string>> current;
  current.resize(vars+1);
  bool working = true;

  for (std::size_t i = 0; i < (std::size_t(1)<<vars); i++) {
    std::string key;
    for (std::size_t j = 0; j < vars; j++) {
      key += (i & (1ULL<<j)) ? '#' : '.';
    }
    auto it = behavior.find(key);
    if (it == behavior.end()) {
      current[CountOnes(key)].insert(key);
    } else if (polarity == it->second) {
      done.insert(key);
      current[CountOnes(key)].insert(key);
    }
  }

  while (working) {
    working = false;
    std::vector<std::set<std::string>> nextbatch;
    nextbatch.resize(current.size()-1);

    for (std::size_t ones = 0; ones+1 < current.size(); ones++) {
      if (!current[ones+1].empty()) {
        for (auto const& t1 : current[ones]) {
          for (auto const& t2 : current[ones+1]) {
            if (auto ix = OffByOne(t1, t2); ix != std::string::npos) {
              auto d1 = done.erase(t1);
              auto d2 = done.erase(t2);

              auto key = t1;
              key[ix] = '-';
              nextbatch[ones].insert(key);
              working = true;

              if (d1 || d2) done.insert(key);
            }
          }
        }
      }
    }
    current = nextbatch;
  }

  return done;
}

auto RunStream(
  Machine m,
  std::istream & in,
  std::ostream & out
) -> ValueType
{
  ValueType answer {};
  Run(m,
    [&]() -> ValueType { return in.get(); },
    [&](ValueType o) {
      if (o < 256) out << char(o); else answer = o; });
  return answer;
}

auto GetCounterExample(std::istream & in) -> std::string {
  std::string line1, line2, line3, line4;

  // Skip lines until the counter example starts
  while(std::getline(in, line1)) {
    if (line1 == "Didn't make it across:") {
      break;
    }
  }

  std::string result;

  while (std::getline(in, line1)) { // whitespace
    std::getline(in, line1); // air
    std::getline(in, line2); // air
    std::getline(in, line3); // air
    std::getline(in, line4); // platform

    std::size_t at_index;
    if ((at_index = line1.find('@')) != std::string::npos) {
      result += line4[at_index];
    } else if ((at_index = line2.find('@')) != std::string::npos) {
      result += line4[at_index];
    } else if ((at_index = line3.find('@')) != std::string::npos) {
      result += line4[at_index];
      if (line4[at_index] == '.') {
        result += line4.substr(at_index+1);
        return result;
      }
    } else {
      at_index = line4.find('@');
      result += '.';
      result += line4.substr(at_index+1);
      return result;
    }
  }

  return "";
}

auto LearnExample(
  std::vector<std::size_t> const& window,
  std::map<std::string, bool> & behavior,
  std::string::const_iterator begin,
  std::string::const_iterator const end,
  auto on_success
) -> void
{
top:
  // Standing on a hole; game over
  if (*begin == '.') return;

  // Reached the end of the platform, report success
  if (std::all_of(begin, end, [](auto c) { return c == '#'; })) {
    on_success(); return;
  }

  // Compute the sensor values
  std::string key;
  std::size_t tail = std::distance(begin, end);
  for (auto i : window) {
    key += i < tail ? begin[i] : '#';
  }

  auto [it, added] = behavior.try_emplace(std::move(key), false);
  if (!added) {
    // We've seen this sensor value before, do the same thing as last time
    begin += it->second ? 4 : 1;
    goto top;
  } else {
    LearnExample(window, behavior, begin + 1, end, on_success);
    it->second = true;
    LearnExample(window, behavior, begin + 4, end, on_success);
    behavior.erase(it);
  }
}

auto LearnAll(
  std::vector<std::size_t> const& window,
  std::map<std::string, bool> & behavior,
  std::vector<std::string>::const_iterator const example,
  std::vector<std::string>::const_iterator const end,
  auto k
) -> void
{
  if (example == end) {
    k();
  } else {
    LearnExample(
      window, behavior,
      example->begin(),
      example->end(),
      [&]() {
        LearnAll(window, behavior, std::next(example), end, k);
      });
  }

}

auto EnhanceSensors(
  std::size_t const n,
  std::vector<std::vector<std::size_t>> const& previous
) {
  std::vector<std::vector<std::size_t>> result;

  for (auto const& v : previous) {
    auto const start = v.empty() ? 1 : v.back() + 1;
    for (std::size_t i = start; i <= n; i++) {
      result.push_back(v);
      result.back().push_back(i);
    }
  }
  return result;
}

auto Compute(
  Machine machine,
  std::size_t const maxsensors,
  std::vector<std::string> const& examples,
  char const* const input
) {

  std::istringstream in {input};
  std::stringstream out;
  auto const output = RunStream(machine, in, out);

  if (output > 0) {
    out << "Hull damage: " << output << std::endl;
  } else {
    out << "Learned " << GetCounterExample(out) << std::endl;
  }

  std::vector<std::vector<std::size_t>> sensors {{}};
  bool searching = true;
  while(searching && !sensors.empty()) {
    for (auto const& sensor : sensors) {
      std::map<std::string, bool> cases;
      LearnAll(sensor, cases, examples.begin(), examples.end(), [&]() {
        searching = false;
        for (bool const p : {true,false}) {
          auto const terms = QuineMcCluskey(p, sensor.size(), cases);
          out << (p ? "\nTRUE\n" : "\nFALSE\n");
          for (auto const s : sensor) {
            out << char('A'+s-1);
          }
          out << std::endl;
          for (auto const& term : terms) {
            out << term << std::endl;
          }
        }
      });
    }
    if (searching) {
      sensors = EnhanceSensors(maxsensors, sensors);
    }
  }
}

} // namespace

auto Main(std::istream & in, std::ostream & out) -> void
{
  Machine machine {ParseStream(in)};

  Compute(machine, 4,
  { "#####.###########",
    "#####.##.########",
    "#####.#.#########",
    "#####.#..########"
    "#####..#.########",
    "#####...#########",
  },
    "OR  A J\n"
    "AND C J\n"
    "NOT J J\n"
    "AND D J\n"
    "WALK\n"
  );
  // FALSE
  // BDE
  // ##-
  // --.
  // n(AC or nD)
  // n(AC) and D

  Compute(std::move(machine), 9,
  { "#####.############",
    "#####.###...#.####",
    "#####.##.#########",
    "#####.##.##...####",
    "#####.#.##########",
    "#####.#.##..#.####",
    "#####.#.##...#####",
    "#####.#.#.##..####",
    "#####.#..#########",
    "#####..###.#..####",
    "#####..##.#.######",
    "#####..#.#########",
    "#####..#.###.#####",
    "#####...##########",
    "#####...####..####",
  },
    "NOT H J\n"
    "OR  C J\n"
    "AND B J\n"
    "AND A J\n"
    "NOT J J\n"
    "AND D J\n"
    "RUN\n"
  );
  // FALSE
  // 3
  // ABCDH
  // ###--
  // ##--.
  // ---.-
  //
  // n(ABC or ABnH or nD)
  // n(AB(C or nH) or nD)
  // n(AB(C or nH)) and D
}