Solve Day 20 Part 1

Author: zeichensystem

CMakeLists.txt

@@ -7,7 +7,7 @@ set(CMAKE_CXX_STANDARD_REQUIRED True)
 set(CMAKE_CXX_EXTENSIONS OFF)
 
 if (APPLE OR UNIX OR LINUX)
- set(WARNING_FLAGS_CXX -Wall -Wextra -Wpedantic -Wvla -Wshadow -Wundef -Wmisleading-indentation -Wnull-dereference -Wswitch-default -Wno-newline-eof -Wno-unused-function -Wno-unused-parameter)
+ set(WARNING_FLAGS_CXX -Wall -Wextra -Wpedantic -Wvla -Wshadow -Wundef -Wmisleading-indentation -Wnull-dereference -Wshadow -Wundef -Wstrict-overflow=5 -Wsign-promo -Wcast-align -Wcast-qual -Woverloaded-virtual -Wredundant-decls -Wctor-dtor-privacy -Wdisabled-optimization -Wformat=2 -Winit-self -Wswitch-default -Wno-newline-eof -Wno-unused-function -Wno-unused-parameter)
  set(CMAKE_CXX_COMPILER "/usr/bin/clang++")
 endif ()
 
@@ -34,7 +34,7 @@ if(ipo_available AND (NOT CMAKE_BUILD_TYPE MATCHES Debug) AND (NOT CMAKE_BUILD_T
  message("-- IPO enabled")
 endif()
 
-set(TARGETS day-01 day-02 day-03 day-04 day-05 day-06 day-07 day-08 day-09 day-10 day-11 day-12 day-13 day-14 day-15 day-16 day-17 day-18 day-19) # Add the other days as you please.
+set(TARGETS day-01 day-02 day-03 day-04 day-05 day-06 day-07 day-08 day-09 day-10 day-11 day-12 day-13 day-14 day-15 day-16 day-17 day-18 day-19 day-20) # Add the other days as you please.
 
 list(LENGTH TARGETS NUM_TARGETS)
 
@@ -81,6 +81,7 @@ add_custom_target("run-all"
  COMMAND day-17
  COMMAND day-18
  COMMAND day-19
+ COMMAND day-20
 
  WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/bin
 )

day-20/day-20.cpp

@@ -0,0 +1,277 @@
+#include <unordered_map>
+#include <set>
+#include <array>
+#include <queue>
+#include "../aoclib/aocio.hpp"
+
+/*
+ Problem: https://adventofcode.com/2023/day/20
+ 
+ Solutions: 
+ - Part 1: 912199500
+ - Part 2: 
+ Notes: 
+
+*/
+
+enum class Pulse {Low, High}; 
+
+class Network;
+
+class Module 
+{
+protected: 
+ std::unordered_map<std::string, Pulse> input_pulses; 
+ std::vector<std::string> outputs; 
+ Pulse state; 
+ virtual void update_state() {};
+
+public: 
+ friend Network;
+ const std::string name;
+
+ Module(const std::string& name, const std::vector<std::string>& outputs) : outputs(outputs), name(name) 
+ {
+ state = Pulse::Low; 
+ }; 
+
+ virtual ~Module() = default;
+
+ // Returns true if the module will send a pulse. 
+ virtual bool receive_pulse(const std::string& sender_name, Pulse p) 
+ {
+ assert(input_pulses.contains(sender_name));
+ input_pulses.at(sender_name) = p; 
+ return true; 
+ }
+
+ virtual void forward_pulse(Network& network, std::set<std::string>& sends_pulse, bool print = false); // Defined after Network.
+};
+
+class Network 
+{
+public: 
+ std::unordered_map<std::string, std::unique_ptr<Module>> modules; 
+
+ void insert_module(std::unique_ptr<Module> mod) 
+ {
+ if (modules.contains(mod->name)) {
+ throw std::invalid_argument("Network::insert_module: Duplicate module"); 
+ }
+ modules.insert({mod->name, std::move(mod)}); 
+ update_connections();
+ }
+
+ int64_t push_button(int n = 1)
+ {
+ int low_pulses = 0; 
+ int high_pulses = 0; 
+
+ for (int i = 0; i < n; ++i) {
+ low_pulses += 1; 
+ std::queue<Module*> queue; 
+ queue.push(modules.at("broadcaster").get());
+
+ while (!queue.empty()) {
+ Module *mod = queue.front();
+ queue.pop();
+
+ std::set<std::string> will_send_pulse; 
+ mod->forward_pulse(*this, will_send_pulse); 
+ if (mod->state == Pulse::Low) {
+ low_pulses += mod->outputs.size(); 
+ } else {
+ high_pulses += mod->outputs.size();
+ }
+ for (const std::string& out_name : will_send_pulse) {
+ assert(modules.contains(out_name));
+ queue.push(modules.at(out_name).get());
+ }
+ }
+ }
+ return low_pulses * high_pulses;
+ }
+
+private: 
+ void update_connections() 
+ {
+ for (auto& [input_name, input_mod] : modules) {
+ for (const std::string& output_name : input_mod->outputs) {
+ if (!modules.contains(output_name)) {
+ continue;
+ }
+ Module *output_mod = modules.at(output_name).get();
+ output_mod->input_pulses.insert_or_assign(input_name, Pulse::Low);
+ }
+ }
+ }
+};
+ 
+void Module::forward_pulse(Network& network, std::set<std::string>& will_send_pulse, bool print) 
+{
+ update_state();
+ for (const std::string& output_name : outputs) {
+ if (!network.modules.contains(output_name)) {
+ continue;
+ }
+ Module *out_mod = network.modules.at(output_name).get();
+ if (print) {
+ std::string state_str = state == Pulse::Low ? " -low-> " : " -high-> ";
+ std::cout << name << state_str << output_name << "\n";
+ }
+ bool will_send = out_mod->receive_pulse(name, state); 
+ if (will_send) {
+ will_send_pulse.insert(output_name);
+ }
+ }
+}
+
+class FlipFlop : public Module 
+{
+private: 
+ bool on = false; 
+
+public:
+ FlipFlop(const std::string& name, const std::vector<std::string>& outputs) : Module(name, outputs) 
+ {
+ state = Pulse::Low; 
+ }
+
+ bool receive_pulse(const std::string& sender_name, Pulse p) override
+ {
+ if (p == Pulse::High) {
+ return false; 
+ } else {
+ state = on ? Pulse::Low : Pulse::High; 
+ on = !on;
+ return true;
+ }
+ }
+
+};
+
+class Conjunction : public Module 
+{
+public:
+ Conjunction(const std::string& name, const std::vector<std::string>& outputs) : Module(name, outputs) 
+ {
+ state = Pulse::Low; 
+ }
+
+protected:
+ void update_state() override
+ {
+ auto input_low = std::find_if(input_pulses.cbegin(), input_pulses.cend(), [](const auto& name_pulse) {return name_pulse.second == Pulse::Low;});
+ bool all_inputs_high = input_low == input_pulses.cend(); 
+ if (all_inputs_high) {
+ state = Pulse::Low; 
+ } else {
+ state = Pulse::High;
+ }
+ }
+};
+
+class Broadcast : public Module 
+{
+public: 
+ Broadcast(const std::string& name, const std::vector<std::string>& outputs) : Module(name, outputs)
+ {
+ state = Pulse::Low; 
+ }
+
+ bool receive_pulse(const std::string& sender_name, Pulse p) override
+ {
+ state = p; 
+ return true; 
+ }
+};
+
+void parse_network(const std::vector<std::string>& lines, Network& network)
+{
+ for (std::string line : lines) {
+ aocio::str_remove_whitespace(line);
+ if (!line.size()) {
+ continue;
+ }
+ std::size_t arrow_idx = line.find("->", 0); 
+ if (arrow_idx == std::string::npos) {
+ throw std::invalid_argument("parse_network: Missing arrow"); 
+ }
+
+ std::string lhs = line.substr(0, arrow_idx); 
+ const std::string& rhs = line.substr(arrow_idx + 2, line.size()); 
+
+ if (lhs.size() < 2 || rhs.size() < 1) {
+ throw std::invalid_argument("parse_network: Assignment too short"); 
+ }
+
+ std::vector<std::string> dest_mods;
+ aocio::line_tokenise(rhs, ",", "", dest_mods);
+
+ if (dest_mods.size() == 0) {
+ throw std::invalid_argument("parse_network: No destination modules"); 
+ }
+
+ const char module_sym = lhs.at(0); 
+
+ if (module_sym != '%' && module_sym != '&') {
+ if (lhs != "broadcaster") {
+ throw std::invalid_argument("parse_network: Invalid module type"); 
+ }
+ std::unique_ptr<Module> mod = std::make_unique<Broadcast>(lhs, dest_mods);
+ network.insert_module(std::move(mod));
+ } else {
+ lhs = lhs.substr(1, lhs.size()); 
+ if (module_sym == '%') {
+ std::unique_ptr<Module> mod = std::make_unique<FlipFlop>(lhs, dest_mods);
+ network.insert_module(std::move(mod));
+ } else {
+ std::unique_ptr<Module> mod = std::make_unique<Conjunction>(lhs, dest_mods);
+ network.insert_module(std::move(mod));
+ }
+ }
+ }
+}
+
+
+int64_t part_one(const std::vector<std::string>& lines)
+{
+ Network network; 
+ parse_network(lines, network);
+ return network.push_button(1000);
+}
+
+int64_t part_two(const std::vector<std::string>& lines)
+{
+ return -1; 
+}
+
+int main()
+{
+ aocio::print_day();
+ std::vector<std::string> lines;
+ std::string_view fname = AOC_INPUT_DIR"input.txt";
+ bool file_loaded = aocio::file_getlines(fname, lines);
+ if (!file_loaded) {
+ std::cerr << "Error: " << "File '" << fname << "' not found\n";
+ return EXIT_FAILURE;
+ } 
+
+ aocio::remove_leading_empty_lines(lines);
+ if (!lines.size()) {
+ std::cerr << "Error: " << "Input is empty";
+ return EXIT_FAILURE;
+ }
+
+ try {
+ int64_t p1 = part_one(lines); 
+ std::cout << "Part 1: " << p1 << "\n";
+ int64_t p2 = part_two(lines);
+ std::cout << "Part 2: " << p2 << "\n";
+ } catch (const std::exception& err) {
+ std::cerr << "Error: " << err.what() << "\n";
+ return EXIT_FAILURE;
+ }
+
+ return EXIT_SUCCESS;
+}

day-20/input-example.txt

@@ -0,0 +1,5 @@
+broadcaster -> a
+%a -> inv, con
+&inv -> b
+%b -> con
+&con -> output