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This commit is contained in:
Eric Mertens 2022-11-10 11:11:02 -08:00
parent bfe57e4487
commit 262c339920
1 changed files with 36 additions and 20 deletions
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56
2019/18.cpp
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@ -94,7 +94,7 @@ auto FindDistances(Map const& map, Features const& features) -> Distances {
Distances distances;
for (auto && [start_letter, start_coord] : features) {
if (islower(start_letter) || start_letter == '@') {
if (!std::isupper(start_letter)) {
FindDistancesFrom(map, features, distances, start_letter, start_coord);
}
}
@ -102,12 +102,6 @@ auto FindDistances(Map const& map, Features const& features) -> Distances {
return distances;
}
struct P1S {
char location;
unsigned long long keys;
auto operator<=>(P1S const&) const = default;
};
auto HasKey(Doors doors, char key) {
return doors.test(std::toupper(key) - 'A');
}
@ -116,26 +110,31 @@ auto SetKey(Doors doors, char key) {
return doors.set(std::toupper(key) - 'A');
}
auto Part1(Distances const& distances) -> std::int64_t {
std::set<P1S> seen;
std::multimap<std::int64_t, std::pair<char, Doors>> todo
{{0, {'@', Doors()}}};
auto SolveMaze(Distances const& distances, std::set<char> const initial_locations) -> std::int64_t {
// Track current positions and current set of keys in easy to compare form
using Visited = std::pair<std::set<char>, unsigned long long>;
std::set<Visited> seen;
std::multimap<std::int64_t, std::pair<std::set<char>, Doors>> todo
{{0, {initial_locations, Doors()}}};
while (!todo.empty()) {
auto it = todo.begin();
auto [steps, ld] = *it;
auto& [l,keys] = ld;
auto& [locations,keys] = ld;
todo.erase(it);
if (keys.all()) { return steps; }
if (seen.insert({l,keys.to_ullong()}).second) {
auto dit = distances.find(l);
if (dit != distances.end()) {
for (auto && [next, costneed] : dit->second) {
if (seen.insert({locations,keys.to_ullong()}).second) {
for (auto location : locations) {
auto locations1 = locations; locations1.erase(location);
for (auto && [next, costneed] : distances.at(location)) {
auto [cost, need] = costneed;
if ((need & (~keys)).none()) {
todo.insert({steps + cost, {next, SetKey(keys, next)}});
if ((need & ~keys).none()) {
auto locations2 = locations1; locations2.insert(next);
todo.insert({steps + cost, {locations2, SetKey(keys, next)}});
}
}
}
@ -145,6 +144,20 @@ auto Part1(Distances const& distances) -> std::int64_t {
throw std::runtime_error{"no solution to part 1"};
}
auto UpdateMap(Map& map, Features & features) {
auto start = features['@'];
map[start.y][start.x] = '#';
map[start.y][start.x+1] = '#';
map[start.y][start.x-1] = '#';
map[start.y+1][start.x] = '#';
map[start.y-1][start.x] = '#';
features.erase('@');
features['^'] = Up(Left(start));
features['&'] = Down(Left(start));
features['*'] = Up(Right(start));
features['$'] = Down(Right(start));
}
} // namespace
auto main(int argc, char** argv) -> int {
@ -152,6 +165,9 @@ auto main(int argc, char** argv) -> int {
auto features = FindFeatures(map);
auto distances = FindDistances(map, features);
std::cout << "Part 1: " << Part1(distances) << std::endl;
//std::cout << "Part 2: " << part2 << std::endl;
std::cout << "Part 1: " << SolveMaze(distances, {'@'}) << std::endl;
UpdateMap(map, features);
distances = FindDistances(map, features);
std::cout << "Part 2: " << SolveMaze(distances, {'^', '&', '*', '$'}) << std::endl;
}