AOC2023: Implement day25 part1

7 starts missing + partly broken day22. I might finish these soon...

userspace/aoc2023/CMakeLists.txt

@@ -26,6 +26,7 @@ set(AOC2023_PROJECTS
 	day21
 	day23
 	day24
+	day25
 	full
 )
 

userspace/aoc2023/day25/CMakeLists.txt

@@ -0,0 +1,22 @@
+cmake_minimum_required(VERSION 3.26)
+
+project(aoc2023_day25 CXX)
+
+set(SOURCES
+	main.cpp
+)
+
+add_executable(aoc2023_day25 ${SOURCES})
+target_compile_options(aoc2023_day25 PUBLIC -O2 -g)
+target_link_libraries(aoc2023_day25 PUBLIC libc ban)
+
+add_dependencies(aoc2023_day25 libc-install ban-install)
+
+add_custom_target(aoc2023_day25-install
+	COMMAND ${CMAKE_COMMAND} -E copy ${CMAKE_CURRENT_BINARY_DIR}/aoc2023_day25 ${BANAN_AOC2023_BIN}/day25
+	DEPENDS aoc2023_day25
+	DEPENDS aoc2023_always
+)
+
+add_dependencies(aoc2023 aoc2023_day25)
+add_dependencies(aoc2023-install aoc2023_day25-install)

userspace/aoc2023/day25/main.cpp

@@ -0,0 +1,249 @@
+#include <BAN/HashMap.h>
+#include <BAN/HashSet.h>
+#include <BAN/Sort.h>
+#include <BAN/String.h>
+#include <BAN/Vector.h>
+
+#include <ctype.h>
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+using i8  = int8_t;
+using i16 = int16_t;
+using i32 = int32_t;
+using i64 = int64_t;
+
+using u8  = uint8_t;
+using u16 = uint16_t;
+using u32 = uint32_t;
+using u64 = uint64_t;
+
+struct Component
+{
+	BAN::String name;
+	BAN::Vector<BAN::String> connections;
+};
+
+BAN::HashMap<BAN::String, Component> parse_components(FILE* fp)
+{
+	BAN::HashMap<BAN::String, Component> components;
+
+	char buffer[128];
+	while (fgets(buffer, sizeof(buffer), fp))
+	{
+		BAN::StringView line(buffer);
+		ASSERT(line.back() == '\n');
+		line = line.substring(0, line.size() - 1);
+		if (line.empty())
+			break;
+		
+		auto parts = MUST(line.split(' '));
+		ASSERT(parts.size() >= 2);
+
+		ASSERT(parts.front().back() == ':');
+		parts.front() = parts.front().substring(0, parts.front().size() - 1);
+
+		if (!components.contains(parts.front()))
+			MUST(components.emplace(parts.front(), parts.front()));
+		
+		for (size_t i = 1; i < parts.size(); i++)
+		{
+			MUST(components[parts.front()].connections.emplace_back(parts[i]));
+
+			if (!components.contains(parts[i]))
+				MUST(components.emplace(parts[i], parts[i]));
+			MUST(components[parts[i]].connections.emplace_back(parts.front()));
+		}
+	}
+
+	return components;
+}
+
+BAN::String connection_key(const BAN::String& a, const BAN::String& b)
+{
+	auto comp =
+		[](const auto& a, const auto& b)
+		{
+			ASSERT(a.size() == b.size());
+			for (size_t i = 0; i < a.size(); i++)
+				if (a[i] != b[i])
+					return a[i] < b[i];
+			ASSERT_NOT_REACHED();
+		};
+
+	const auto& s1 = comp(a, b) ? a : b;
+	const auto& s2 = comp(a, b) ? b : a;
+
+	auto key = s1;
+	MUST(key.append(s2));
+	return key;
+}
+
+size_t graph_size(const BAN::HashMap<BAN::String, Component>& graph, const BAN::String& start, const BAN::HashSet<BAN::String>& removed)
+{
+	BAN::HashSet<BAN::String> visited;
+	BAN::HashSet<BAN::String> pending;
+	MUST(pending.insert(start));
+
+	while (!pending.empty())
+	{
+		auto current = *pending.begin();
+		pending.remove(current);
+
+		MUST(visited.insert(current));
+
+		const auto& targets = graph[current].connections;
+		for (const auto& target : targets)
+		{
+			if (removed.contains(connection_key(current, target)))	
+				continue;
+			if (visited.contains(target))
+				continue;
+			MUST(pending.insert(target));
+			MUST(visited.insert(target));
+		}
+	}
+
+	return visited.size();
+}
+
+BAN::Vector<BAN::String> find_shortest_path(const BAN::String& start, const BAN::String& end, const BAN::HashMap<BAN::String, Component>& graph)
+{
+	BAN::HashMap<BAN::String, BAN::Vector<BAN::String>> paths;
+	MUST(paths.insert(start, {}));
+	MUST(paths[start].push_back(start));
+
+	BAN::HashSet<BAN::String> visited;
+	BAN::HashSet<BAN::String> pending;
+	MUST(pending.insert(start));
+
+	while (!pending.empty())
+	{
+		BAN::HashSet<BAN::String> next_pending;
+
+		while (!pending.empty())
+		{
+			auto current = *pending.begin();
+			pending.remove(current);
+			MUST(visited.insert(current));
+
+			if (current == end)
+				return paths[current];
+
+			const auto& targets = graph[current].connections;
+			for (const auto& target : targets)
+			{
+				if (visited.contains(target))
+					continue;
+				if (pending.contains(target))
+					continue;
+				if (next_pending.contains(target))
+					continue;
+				if (paths.contains(target))
+					continue;
+				MUST(next_pending.insert(target));
+				MUST(visited.insert(target));
+
+				MUST(paths.insert(target, paths[current]));
+				MUST(paths[target].push_back(target));
+			}
+		}
+
+		pending = BAN::move(next_pending);
+	}
+
+	ASSERT_NOT_REACHED();
+}
+
+i64 puzzle1(FILE* fp)
+{
+	auto components = parse_components(fp);
+
+	BAN::HashMap<BAN::String, i64> connection_count;
+
+	srand(time(nullptr));
+	for (size_t i = 0; i < 100; i++)
+	{
+		size_t idx1 = rand() % components.size();
+		size_t idx2 = rand() % components.size();
+
+		auto path = find_shortest_path(next(components.begin(), idx1)->key, next(components.begin(), idx2)->key, components);
+		for (size_t j = 1; j < path.size(); j++)
+		{
+			const auto& connection = connection_key(path[j - 1], path[j]);
+			if (!connection_count.contains(connection))
+				MUST(connection_count.insert(connection, 0));
+			connection_count[connection]++;
+		}
+	}
+
+	struct Connection
+	{
+		BAN::String connection;
+		i64 count;
+	};
+	BAN::Vector<Connection> hot_connections;
+	for (const auto& [connection, count] : connection_count)
+		MUST(hot_connections.emplace_back(connection, count));
+	BAN::sort::sort(hot_connections.begin(), hot_connections.end(), [](const auto& a, const auto& b) { return a.count > b.count; });
+
+	for (size_t depth = 0; depth < hot_connections.size(); depth++)
+	{
+		for (size_t i = 0; i < depth; i++)
+		{
+			for (size_t j = i + 1; j < depth; j++)
+			{
+				for (size_t k = j + 1; k < depth; k++)
+				{
+					BAN::HashSet<BAN::String> removed;
+					MUST(removed.insert(hot_connections[i].connection));
+					MUST(removed.insert(hot_connections[j].connection));
+					MUST(removed.insert(hot_connections[k].connection));
+
+					size_t lhs_size = graph_size(components, hot_connections[i].connection.sv().substring(0, 3), removed);
+					if (lhs_size == components.size())
+						continue;
+
+					size_t rhs_size = graph_size(components, hot_connections[i].connection.sv().substring(3, 3), removed);
+					if (rhs_size == components.size())
+						continue;
+
+					if (lhs_size + rhs_size == components.size())
+						return lhs_size * rhs_size;
+				}
+			}
+		}
+	}
+
+	return -1;
+}
+
+i64 puzzle2(FILE* fp)
+{
+	(void)fp;
+	return -1;
+}
+
+int main(int argc, char** argv)
+{
+	const char* file_path = "/usr/share/aoc2023/day25_input.txt";
+
+	if (argc >= 2)
+		file_path = argv[1];
+
+	FILE* fp = fopen(file_path, "r");
+	if (fp == nullptr)
+	{
+		perror("fopen");
+		return 1;
+	}
+
+	printf("puzzle1: %" PRId64 "\n", puzzle1(fp));
+
+	fseek(fp, 0, SEEK_SET);
+
+	printf("puzzle2: %" PRId64 "\n", puzzle2(fp));
+
+	fclose(fp);
+}

userspace/aoc2023/full/main.cpp

@@ -4,7 +4,7 @@
 
 int main()
 {
-	for (int i = 1; i <= 24; i++)
+	for (int i = 1; i <= 25; i++)
 	{
 		if (i == 22)
 			continue;