diff --git a/userspace/aoc2023/CMakeLists.txt b/userspace/aoc2023/CMakeLists.txt index 19ef3082..d111f4b5 100644 --- a/userspace/aoc2023/CMakeLists.txt +++ b/userspace/aoc2023/CMakeLists.txt @@ -16,6 +16,7 @@ set(AOC2023_PROJECTS day11 day12 day13 + day14 ) set(BANAN_AOC2023_BIN ${BANAN_BIN}/aoc2023) diff --git a/userspace/aoc2023/day14/CMakeLists.txt b/userspace/aoc2023/day14/CMakeLists.txt new file mode 100644 index 00000000..781002a4 --- /dev/null +++ b/userspace/aoc2023/day14/CMakeLists.txt @@ -0,0 +1,22 @@ +cmake_minimum_required(VERSION 3.26) + +project(aoc2023_day14 CXX) + +set(SOURCES + main.cpp +) + +add_executable(aoc2023_day14 ${SOURCES}) +target_compile_options(aoc2023_day14 PUBLIC -O2 -g) +target_link_libraries(aoc2023_day14 PUBLIC libc ban) + +add_dependencies(aoc2023_day14 libc-install ban-install) + +add_custom_target(aoc2023_day14-install + COMMAND ${CMAKE_COMMAND} -E copy ${CMAKE_CURRENT_BINARY_DIR}/aoc2023_day14 ${BANAN_AOC2023_BIN}/day14 + DEPENDS aoc2023_day14 + DEPENDS aoc2023_always +) + +add_dependencies(aoc2023 aoc2023_day14) +add_dependencies(aoc2023-install aoc2023_day14-install) diff --git a/userspace/aoc2023/day14/main.cpp b/userspace/aoc2023/day14/main.cpp new file mode 100644 index 00000000..d26c2df8 --- /dev/null +++ b/userspace/aoc2023/day14/main.cpp @@ -0,0 +1,226 @@ +#include +#include +#include +#include +#include + +#include +#include +#include + +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; + +enum class Tile { Empty, RollableRock, StaticRock }; +enum class Direction { North, South, West, East }; + +using Platform = BAN::Vector>; + +Platform parse_platform(FILE* fp) +{ + Platform platform; + + 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()) + continue; + + auto char_to_tile = + [](char c) + { + if (c == '.') + return Tile::Empty; + if (c == 'O') + return Tile::RollableRock; + if (c == '#') + return Tile::StaticRock; + ASSERT_NOT_REACHED(); + }; + + MUST(platform.emplace_back(line.size())); + for (size_t i = 0; i < line.size(); i++) + platform.back()[i] = char_to_tile(line[i]); + } + + return platform; +} + +void tilt_platform(Platform& platform, Direction direction) +{ + switch (direction) + { + case Direction::North: + for (size_t y = 0; y < platform.size(); y++) + for (size_t x = 0; x < platform.front().size(); x++) + if (platform[y][x] == Tile::RollableRock) + for (size_t y_off = 1; y_off <= y && platform[y - y_off][x] == Tile::Empty; y_off++) + BAN::swap(platform[y - y_off + 1][x], platform[y - y_off][x]); + break; + case Direction::West: + for (size_t x = 0; x < platform.front().size(); x++) + for (size_t y = 0; y < platform.size(); y++) + if (platform[y][x] == Tile::RollableRock) + for (size_t x_off = 1; x_off <= x && platform[y][x - x_off] == Tile::Empty; x_off++) + BAN::swap(platform[y][x - x_off + 1], platform[y][x - x_off]); + break; + case Direction::South: + for (size_t y = platform.size(); y > 0; y--) + for (size_t x = 0; x < platform.front().size(); x++) + if (platform[y - 1][x] == Tile::RollableRock) + for (size_t y_off = 1; y + y_off - 1 < platform.size() && platform[y + y_off - 1][x] == Tile::Empty; y_off++) + BAN::swap(platform[y + y_off - 2][x], platform[y + y_off - 1][x]); + break; + case Direction::East: + for (size_t x = platform.front().size(); x > 0; x--) + for (size_t y = 0; y < platform.size(); y++) + if (platform[y][x - 1] == Tile::RollableRock) + for (size_t x_off = 1; x + x_off - 1 < platform.front().size() && platform[y][x + x_off - 1] == Tile::Empty; x_off++) + BAN::swap(platform[y][x + x_off - 2], platform[y][x + x_off - 1]); + break; + default: + ASSERT_NOT_REACHED(); + } +} + +i64 puzzle1(FILE* fp) +{ + auto platform = parse_platform(fp); + + tilt_platform(platform, Direction::North); + + i64 result = 0; + for (size_t y = 0; y < platform.size(); y++) + for (size_t x = 0; x < platform.front().size(); x++) + if (platform[y][x] == Tile::RollableRock) + result += platform.size() - y; + return result; +} + +struct PlatformKey +{ + BAN::Array data; + + bool operator==(const PlatformKey& other) const + { + return memcmp(data.data(), other.data.data(), data.size() * sizeof(decltype(data)::value_type)) == 0; + } +}; + +struct PlatformKeyHash +{ + BAN::hash_t operator()(const PlatformKey& key) const + { + return key.data.back(); + } +}; + +i64 puzzle2(FILE* fp) +{ + auto platform = parse_platform(fp); + ASSERT(platform.size() * platform.front().size() == 100 * 100); + + BAN::HashMap hit_cache; + + auto build_cache_key = + [](const Platform& platform) -> PlatformKey + { + PlatformKey key; + for (size_t i = 0; i < 100 * 100; i++) + { + const size_t elem = i / 64; + const size_t bit = i % 64; + if (platform[i / 100][i % 100] == Tile::RollableRock) + key.data[elem] |= 1ull << bit; + } + return key; + }; + + PlatformKey cycle_begin_key; + i64 cycle_begin = -1; + i64 cycle_length = -1; + + i64 missing_cycles = 1'000'000'000; + + for (i64 i = 0; missing_cycles > 0; i++, missing_cycles--) + { + auto key = build_cache_key(platform); + + if (cycle_begin == -1) + { + if (hit_cache.contains(key)) + { + cycle_begin = i; + cycle_begin_key = key; + } + else + { + MUST(hit_cache.insert(key, i)); + } + } + else + { + if (key == cycle_begin_key) + { + cycle_length = (i - hit_cache[key]) / 2; + break; + } + } + + tilt_platform(platform, Direction::North); + tilt_platform(platform, Direction::West); + tilt_platform(platform, Direction::South); + tilt_platform(platform, Direction::East); + } + + if (cycle_length != -1) + missing_cycles %= cycle_length; + + for (; missing_cycles > 0; missing_cycles--) + { + tilt_platform(platform, Direction::North); + tilt_platform(platform, Direction::West); + tilt_platform(platform, Direction::South); + tilt_platform(platform, Direction::East); + } + + i64 result = 0; + for (size_t y = 0; y < platform.size(); y++) + for (size_t x = 0; x < platform.front().size(); x++) + if (platform[y][x] == Tile::RollableRock) + result += platform.size() - y; + return result; +} + +int main(int argc, char** argv) +{ + const char* file_path = "/usr/share/aoc2023/day14_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); +}