AOC2023: Implement day18 part 1

userspace/aoc2023/CMakeLists.txt

@@ -20,6 +20,7 @@ set(AOC2023_PROJECTS
 	day15
 	day16
 	day17
+	day18
 	full
 )
 

userspace/aoc2023/day18/CMakeLists.txt

@@ -0,0 +1,22 @@
+cmake_minimum_required(VERSION 3.26)
+
+project(aoc2023_day18 CXX)
+
+set(SOURCES
+	main.cpp
+)
+
+add_executable(aoc2023_day18 ${SOURCES})
+target_compile_options(aoc2023_day18 PUBLIC -O2 -g)
+target_link_libraries(aoc2023_day18 PUBLIC libc ban)
+
+add_dependencies(aoc2023_day18 libc-install ban-install)
+
+add_custom_target(aoc2023_day18-install
+	COMMAND ${CMAKE_COMMAND} -E copy ${CMAKE_CURRENT_BINARY_DIR}/aoc2023_day18 ${BANAN_AOC2023_BIN}/day18
+	DEPENDS aoc2023_day18
+	DEPENDS aoc2023_always
+)
+
+add_dependencies(aoc2023 aoc2023_day18)
+add_dependencies(aoc2023-install aoc2023_day18-install)

userspace/aoc2023/day18/main.cpp

@@ -0,0 +1,265 @@
+#include <BAN/HashSet.h>
+#include <BAN/StringView.h>
+
+#include <ctype.h>
+#include <inttypes.h>
+#include <stdio.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 Position
+{
+	i32 x;
+	i32 y;
+
+	bool operator==(const Position& other) const
+	{
+		return x == other.x && y == other.y;
+	}
+
+	Position& operator+=(const Position& other)
+	{
+		x += other.x;
+		y += other.y;
+		return *this;
+	}
+
+	Position operator+(const Position& other) const
+	{
+		Position temp = *this;
+		temp += other;
+		return temp;
+	}
+};
+
+struct PositionHash
+{
+	BAN::hash_t operator()(const Position& position) const
+	{
+		return BAN::u64_hash(((u64)position.x << 32) | (u64)position.y);
+	}
+};
+
+enum Direction { North, West, South, East };
+
+static constexpr Direction char_to_dir(char c)
+{
+	if (c == 'U')
+		return Direction::North;
+	if (c == 'D')
+		return Direction::South;
+	if (c == 'L')
+		return Direction::West;
+	if (c == 'R')
+		return Direction::East;
+	ASSERT_NOT_REACHED();
+}
+
+static constexpr Position s_dir_offset[] {
+	{ .x =  0, .y = -1 },
+	{ .x = -1, .y =  0 },
+	{ .x =  0, .y =  1 },
+	{ .x =  1, .y =  0 },
+};
+
+i64 solve_general(FILE* fp, auto parse_dir, auto parse_count)
+{
+	BAN::HashSetUnstable<Position, PositionHash> path;
+	BAN::HashSetUnstable<Position, PositionHash> lpath;
+	BAN::HashSetUnstable<Position, PositionHash> rpath;
+
+	Position current_pos { 0, 0 };
+	MUST(path.insert(current_pos));
+
+	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 dir = parse_dir(line);
+		i64 count = parse_count(line);
+
+		Position loff, roff;
+		switch (dir)
+		{
+			case Direction::North:
+				loff = s_dir_offset[Direction::West];
+				roff = s_dir_offset[Direction::East];
+				break;
+			case Direction::South:
+				loff = s_dir_offset[Direction::East];
+				roff = s_dir_offset[Direction::West];
+				break;
+			case Direction::East:
+				loff = s_dir_offset[Direction::North];
+				roff = s_dir_offset[Direction::South];
+				break;
+			case Direction::West:
+				loff = s_dir_offset[Direction::South];
+				roff = s_dir_offset[Direction::North];
+				break;
+		}
+
+		for (i64 i = 0; i < count; i++)
+		{
+			current_pos += s_dir_offset[dir];
+			MUST(path.insert(current_pos));
+			MUST(lpath.insert(current_pos + loff));
+			MUST(rpath.insert(current_pos + roff));
+		}
+	}
+
+	for (auto position : path)
+	{
+		if (lpath.contains(position))
+			lpath.remove(position);
+		if (rpath.contains(position))
+			rpath.remove(position);
+	}
+
+	auto find_min_and_remove_duplicates =
+		[](auto& source, auto& destination, i32& minimum)
+		{
+			for (auto it = source.begin(); it != source.end();)
+			{
+				if (!destination.contains(*it))
+				{
+					minimum = BAN::Math::min(minimum, it->x);
+					it++;
+				}
+				else
+				{
+					source.remove(*it);
+					destination.remove(*it);
+					it = source.begin();
+				}
+			}
+		};
+
+	i32 lmin_x = INT32_MAX;
+	find_min_and_remove_duplicates(lpath, rpath, lmin_x);
+
+	i32 rmin_x = INT32_MAX;
+	find_min_and_remove_duplicates(rpath, lpath, rmin_x);
+	
+	ASSERT(lmin_x != rmin_x);
+	auto& expand = (lmin_x < rmin_x) ? rpath : lpath;
+
+	BAN::HashSetUnstable<Position, PositionHash> visited;
+	BAN::HashSetUnstable<Position, PositionHash> inner_area;
+
+	while (!expand.empty())
+	{
+		auto position = *expand.begin();
+		expand.remove(position);
+
+		MUST(inner_area.insert(position));
+		MUST(visited.insert(position));
+
+		for (i8 dir = 0; dir < 4; dir++)
+		{
+			auto next = position + s_dir_offset[dir];
+			if (visited.contains(next) || path.contains(next))
+				continue;
+			MUST(expand.insert(next));
+			MUST(visited.insert(next));
+		}
+	}
+	
+	return path.size() + inner_area.size();
+}
+
+i64 puzzle1(FILE* fp)
+{
+	auto parse_dir =
+		[](auto line)
+		{
+			if (line[0] == 'U')
+				return Direction::North;
+			if (line[0] == 'D')
+				return Direction::South;
+			if (line[0] == 'L')
+				return Direction::West;
+			if (line[0] == 'R')
+				return Direction::East;
+			ASSERT_NOT_REACHED();
+		};
+
+	auto parse_count =
+		[](auto line)
+		{
+			i64 result = 0;
+			for (size_t i = 2; i < line.size() && isdigit(line[i]); i++)
+				result = (result * 10) + (line[i] - '0');
+			return result;
+		};
+
+	return solve_general(fp, parse_dir, parse_count);
+}
+
+i64 puzzle2(FILE* fp)
+{
+	//(#7a21e3)
+
+	auto parse_dir =
+		[](auto line)
+		{
+			line = line.substring(*line.find('('));
+			if (line[7] == '0')
+				return Direction::East;
+			if (line[7] == '1')
+				return Direction::South;
+			if (line[7] == '2')
+				return Direction::West;
+			if (line[7] == '3')
+				return Direction::North;
+			ASSERT_NOT_REACHED();
+		};
+
+	auto parse_count =
+		[](auto line)
+		{
+			line = line.substring(*line.find('('));
+			i64 result = 0;
+			for (size_t i = 2; i < 7; i++)
+				result = (result * 16) + ((isdigit(line[i])) ? (line[i] - '0') : (tolower(line[i] - 'a' + 10)));
+			return result;
+		};
+
+	return solve_general(fp, parse_dir, parse_count);
+}
+
+int main(int argc, char** argv)
+{
+	const char* file_path = "/usr/share/aoc2023/day18_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 <= 16; i++)
+	for (int i = 1; i <= 18; i++)
 	{
 		printf("day %d:\n", i);