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Proposed solutions for 2021 day 23

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Matthew Gretton-Dann
2021-12-23 19:49:33 +00:00
parent fcfdcddd33
commit b53002d48a
2 changed files with 477 additions and 0 deletions
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2021/puzzle-23-01.cc Normal file
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#include <array>
#include <functional>
#include <iostream>
#include <map>
#include <regex>
#include <set>
#include <string>
#include <unordered_map>
#include <unordered_set>
// Map:
// #############
// #ab.c.d.e.fg#
// ###h#i#j#k###
// #l#m#n#o#
// #########
//
// a -1- b -2- c -2- d -2- e -2- f -1- g
// \ / \ / \ / \ /
// 2 2 2 2 2 2 2 2
// + + + +
// h i j k
// | | | |
// 1 1 1 1
// | | | |
// l m n o
using Position = char;
using UInt = int;
using Type = char;
std::multimap<Position, std::pair<Position, UInt>> costs{
{'a', {'b', 1}}, {'b', {'a', 1}}, {'b', {'c', 2}}, {'b', {'h', 2}}, {'c', {'b', 2}},
{'c', {'d', 2}}, {'c', {'h', 2}}, {'c', {'i', 2}}, {'d', {'c', 2}}, {'d', {'e', 2}},
{'d', {'i', 2}}, {'d', {'j', 2}}, {'e', {'d', 2}}, {'e', {'f', 2}}, {'e', {'j', 2}},
{'e', {'k', 2}}, {'f', {'e', 2}}, {'f', {'g', 1}}, {'f', {'k', 2}}, {'g', {'f', 1}},
{'h', {'b', 2}}, {'h', {'c', 2}}, {'h', {'l', 1}}, {'i', {'c', 2}}, {'i', {'d', 2}},
{'i', {'m', 1}}, {'j', {'d', 2}}, {'j', {'e', 2}}, {'j', {'n', 1}}, {'k', {'e', 2}},
{'k', {'f', 2}}, {'k', {'o', 1}}, {'l', {'h', 1}}, {'m', {'i', 1}}, {'n', {'j', 1}},
{'o', {'k', 1}}};
std::map<Type, UInt> multipliers{{'A', 1}, {'B', 10}, {'C', 100}, {'D', 1000}};
struct State
{
auto finished() const noexcept -> bool { return nodes_ == finished_; }
auto size() const noexcept -> UInt { return 15; }
auto node(unsigned idx) noexcept -> Type& { return nodes_[idx]; }
auto node(unsigned idx) const noexcept -> Type const& { return nodes_[idx]; }
bool check_move(unsigned from, unsigned to)
{
if (nodes_[from] == '.' || nodes_[to] != '.') {
return false;
}
if (from > 10) {
// Only move out of the bottom row if we're not meant to be here.
return nodes_[from] != finished_[from];
}
if (from > 6 && from < 11) {
if (to > 10) {
// Only move into bottom position if we're moving the correct piece.
return nodes_[from] == finished_[to];
}
// Moving to top row - anything allowed.
return true;
}
if (from < 7) {
if (to < 7) {
return true;
}
// Can only move down if we're the right type.
return nodes_[from] == finished_[to];
}
abort();
}
bool move(unsigned from, unsigned to)
{
if (!check_move(from, to)) {
return false;
}
std::swap(nodes_[from], nodes_[to]);
return true;
}
constexpr bool operator<(State const& rhs) const noexcept { return nodes_ < rhs.nodes_; }
constexpr bool operator==(State const& rhs) const noexcept { return nodes_ < rhs.nodes_; }
private:
std::array<Type, 15> nodes_{'.'};
static std::array<Type, 15> finished_;
};
template<>
struct std::hash<State>
{
auto operator()(State const& key) const -> std::size_t
{
std::size_t result{0};
for (auto i{0}; i < 15; ++i) {
result <<= 3;
if (key.node(i) != '.') {
result |= key.node(i) - 'A' + 1;
}
}
return result;
}
};
std::array<Type, 15> State::finished_ = {'.', '.', '.', '.', '.', '.', '.', 'A',
'B', 'C', 'D', 'A', 'B', 'C', 'D'};
auto main() -> int
{
std::regex line2_re{R"(#(.)(.)\.(.)\.(.)\.(.)\.(.)(.)#)"};
std::regex line3_re{"###(.)#(.)#(.)#(.)###"};
std::regex line4_re{"#(.)#(.)#(.)#(.)#"};
std::string line;
std::smatch m;
std::getline(std::cin, line);
if (line != "#############") {
std::cerr << "Incorrect first line.\n";
return 1;
}
State initial_state;
std::getline(std::cin, line);
if (!std::regex_search(line, m, line2_re)) {
std::cerr << "Unable to match line 2 " << line << '\n';
return 1;
}
for (unsigned i = 0; i < 7; ++i) {
initial_state.node(i) = m.str(i + 1)[0];
}
std::getline(std::cin, line);
if (!std::regex_search(line, m, line3_re)) {
std::cerr << "Unable to match line 3 " << line << '\n';
return 1;
}
for (unsigned i = 0; i < 4; ++i) {
initial_state.node(7 + i) = m.str(i + 1)[0];
}
std::getline(std::cin, line);
if (!std::regex_search(line, m, line4_re)) {
std::cerr << "Unable to match line 4 " << line << '\n';
return 1;
}
for (unsigned i = 0; i < 4; ++i) {
initial_state.node(11 + i) = m.str(i + 1)[0];
}
std::map<State, UInt> states;
states.insert({initial_state, 0});
std::set<State> visited;
while (!states.empty()) {
auto it{std::min_element(states.begin(), states.end(), [](auto const& lhs, auto const& rhs) {
return lhs.second < rhs.second;
})};
if (visited.size() % 10'000 == 0) {
std::cout << "Visited: " << visited.size() << " number of states: " << states.size()
<< " Min energy: " << it->second << '\n';
}
State state{it->first};
UInt cost{it->second};
visited.insert(state);
states.erase(state);
if (state.finished()) {
std::cout << "Done with cost " << cost << '\n';
return 0;
}
for (unsigned i = 0; i < state.size(); ++i) {
if (state.node(i) == '.') {
continue;
}
auto [it_begin, it_end] = costs.equal_range(i + 'a');
for (auto cost_it{it_begin}; cost_it != it_end; ++cost_it) {
State next_state{state};
if (next_state.move(i, cost_it->second.first - 'a') && !visited.contains(next_state)) {
UInt next_cost = cost + cost_it->second.second * multipliers[state.node(i)];
auto [insert_it, success] = states.insert({next_state, next_cost});
if (!success) {
insert_it->second = std::min(insert_it->second, next_cost);
}
}
}
}
}
std::cerr << "FAILED\n";
return 1;
}

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#include <array>
#include <functional>
#include <iostream>
#include <map>
#include <regex>
#include <set>
#include <string>
// Map:
// 0 1 2 3 4 5 6
// 7 8 9 10
// 11 12 13 14
// 15 16 17 18
// 19 20 21 22
using Position = unsigned;
using UInt = unsigned;
using Type = char;
std::multimap<Position, std::pair<Position, UInt>> legal_moves{
{0, {1, 1}}, {1, {0, 1}}, {1, {2, 2}}, {1, {7, 2}}, {2, {1, 2}}, {2, {3, 2}},
{2, {7, 2}}, {2, {8, 2}}, {3, {2, 2}}, {3, {4, 2}}, {3, {8, 2}}, {3, {9, 2}},
{4, {3, 2}}, {4, {5, 2}}, {4, {9, 2}}, {4, {10, 2}}, {5, {4, 2}}, {5, {6, 1}},
{5, {10, 2}}, {6, {5, 1}}, {7, {1, 2}}, {7, {2, 2}}, {7, {11, 1}}, {8, {2, 2}},
{8, {3, 2}}, {8, {12, 1}}, {9, {3, 2}}, {9, {4, 2}}, {9, {13, 1}}, {10, {4, 2}},
{10, {5, 2}}, {10, {14, 1}}, {11, {7, 1}}, {12, {8, 1}}, {13, {9, 1}}, {14, {10, 1}},
{11, {15, 1}}, {12, {16, 1}}, {13, {17, 1}}, {14, {18, 1}}, {15, {11, 1}}, {16, {12, 1}},
{17, {13, 1}}, {18, {14, 1}}, {15, {19, 1}}, {16, {20, 1}}, {17, {21, 1}}, {18, {22, 1}},
{19, {15, 1}}, {20, {16, 1}}, {21, {17, 1}}, {22, {18, 1}},
};
std::map<Type, UInt> multipliers{{'A', 1}, {'B', 10}, {'C', 100}, {'D', 1000}};
struct State
{
auto finished() const noexcept -> bool { return nodes_ == finished_; }
auto size() const noexcept -> UInt { return node_size; }
auto node(unsigned idx) noexcept -> Type& { return nodes_[idx]; }
auto node(unsigned idx) const noexcept -> Type const& { return nodes_[idx]; }
bool check_move(unsigned from, unsigned to)
{
if (nodes_[from] == '.' || nodes_[to] != '.') {
return false;
}
if (from > 18) {
// Bottom row
// Only move out of the bottom row if we're not meant to be here.
return nodes_[from] != finished_[from];
}
if (from > 14 && from < 19) {
// Second bottom row
if (to > 18) {
// Only move down if we're the right node
return nodes_[from] == finished_[to];
}
// Only move up if we or a node beneath us is incorrect.
if (nodes_[from] != finished_[from]) {
return true;
}
if (nodes_[from + 4] != '.' && nodes_[from + 4] != finished_[from]) {
return true;
}
return false;
}
if (from > 10 && from < 15) {
// Second top row
if (to > 14) {
// Only move down if we're the right node and the very bottom is empty or contains the
// correct node.
if (nodes_[from + 8] != '.' && nodes_[from + 8] != finished_[to]) {
return false;
}
return nodes_[from] == finished_[to];
}
// Only move up if we or a node beneath us is incorrect.
if (nodes_[from] != finished_[from]) {
return true;
}
if (nodes_[from + 4] != '.' && nodes_[from + 4] != finished_[from]) {
return true;
}
if (nodes_[from + 8] != '.' && nodes_[from + 8] != finished_[from]) {
return true;
}
return false;
}
if (from > 6 && from < 11) {
if (to > 10) {
// Only move down if we're the right node and the bottom two rows are empty or contain the
// correct node.
if (nodes_[from + 8] != '.' && nodes_[from + 8] != finished_[to]) {
return false;
}
if (nodes_[from + 12] != '.' && nodes_[from + 12] != finished_[to]) {
return false;
}
return nodes_[from] == finished_[to];
}
if (nodes_[from] != finished_[from]) {
return true;
}
if (nodes_[from + 4] != '.' && nodes_[from + 4] != finished_[from]) {
return true;
}
if (nodes_[from + 8] != '.' && nodes_[from + 8] != finished_[from]) {
return true;
}
if (nodes_[from + 12] != '.' && nodes_[from + 12] != finished_[from]) {
return true;
}
return false;
}
if (from < 7) {
if (to < 7) {
// Can do any move along the row.
return true;
}
// Can only move down if we're the right type.
return nodes_[from] == finished_[to];
}
abort();
}
bool move(unsigned from, unsigned to)
{
if (!check_move(from, to)) {
return false;
}
std::swap(nodes_[from], nodes_[to]);
return true;
}
constexpr bool operator<(State const& rhs) const noexcept { return nodes_ < rhs.nodes_; }
constexpr bool operator==(State const& rhs) const noexcept { return nodes_ < rhs.nodes_; }
constexpr static unsigned node_size{23};
private:
std::array<Type, node_size> nodes_{'.'};
static std::array<Type, node_size> finished_;
};
std::array<Type, State::node_size> State::finished_ = {'.', '.', '.', '.', '.', '.', '.', 'A',
'B', 'C', 'D', 'A', 'B', 'C', 'D', 'A',
'B', 'C', 'D', 'A', 'B', 'C', 'D'};
struct StateCmp
{
constexpr bool operator()(State const* l, State const* r) const noexcept
{
if (l == nullptr && r != nullptr) {
return true;
}
if (r == nullptr) {
return false;
}
return *l < *r;
}
};
auto main() -> int
{
std::regex line2_re{R"(#(.)(.)\.(.)\.(.)\.(.)\.(.)(.)#)"};
std::regex line3_re{"###(.)#(.)#(.)#(.)###"};
std::regex line4_re{"#(.)#(.)#(.)#(.)#"};
std::string line;
std::smatch m;
std::getline(std::cin, line);
if (line != "#############") {
std::cerr << "Incorrect first line.\n";
return 1;
}
State* initial_state = new State;
std::getline(std::cin, line);
if (!std::regex_search(line, m, line2_re)) {
std::cerr << "Unable to match line 2 " << line << '\n';
return 1;
}
for (unsigned i = 0; i < 7; ++i) {
initial_state->node(i) = m.str(i + 1)[0];
}
std::getline(std::cin, line);
if (!std::regex_search(line, m, line3_re)) {
std::cerr << "Unable to match line 3 " << line << '\n';
return 1;
}
for (unsigned i = 0; i < 4; ++i) {
initial_state->node(7 + i) = m.str(i + 1)[0];
}
initial_state->node(11) = 'D';
initial_state->node(12) = 'C';
initial_state->node(13) = 'B';
initial_state->node(14) = 'A';
initial_state->node(15) = 'D';
initial_state->node(16) = 'B';
initial_state->node(17) = 'A';
initial_state->node(18) = 'C';
std::getline(std::cin, line);
if (!std::regex_search(line, m, line4_re)) {
std::cerr << "Unable to match line 4 " << line << '\n';
return 1;
}
for (unsigned i = 0; i < 4; ++i) {
initial_state->node(19 + i) = m.str(i + 1)[0];
}
std::map<State*, UInt, StateCmp> states;
std::multimap<UInt, State*> costs;
states.insert({initial_state, 0});
costs.insert({0, initial_state});
std::set<State*, StateCmp> visited;
while (!states.empty()) {
auto it{costs.begin()};
if (visited.size() % 10'000 == 0) {
std::cout << "Visited: " << visited.size() << " number of states: " << states.size()
<< " Min energy: " << it->first << '\n';
}
State* state{it->second};
UInt cost{it->first};
visited.insert(state);
states.erase(state);
costs.erase(it);
if (state->finished()) {
std::cout << "Done with cost " << cost << '\n';
return 0;
}
for (unsigned i = 0; i < state->size(); ++i) {
if (state->node(i) == '.') {
continue;
}
auto [it_begin, it_end] = legal_moves.equal_range(i);
for (auto move_it{it_begin}; move_it != it_end; ++move_it) {
State* next_state = new State{*state};
if (next_state->move(i, move_it->second.first) && !visited.contains(next_state)) {
UInt next_cost = cost + move_it->second.second * multipliers[state->node(i)];
auto [insert_it, success] = states.insert({next_state, next_cost});
if (!success) {
if (next_cost < insert_it->second) {
insert_it->second = next_cost;
auto [cost_begin, cost_end] = costs.equal_range(cost);
while (cost_begin != cost_end) {
if (*cost_begin->second == *next_state) {
delete next_state;
next_state = cost_begin->second;
costs.erase(cost_begin);
break;
}
++cost_begin;
}
costs.insert({next_cost, next_state});
}
else {
delete next_state;
}
}
else {
costs.insert({next_cost, next_state});
}
}
else {
delete next_state;
}
}
}
}
std::cerr << "FAILED\n";
return 1;
}