157 lines
3.0 KiB
C++
157 lines
3.0 KiB
C++
#include <BAN/Array.h>
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#include <BAN/ScopeGuard.h>
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#include <BAN/StringView.h>
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#include <BAN/Vector.h>
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#include <ctype.h>
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#include <inttypes.h>
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#include <stdio.h>
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using i8 = int8_t;
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using i16 = int16_t;
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using i32 = int32_t;
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using i64 = int64_t;
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using u8 = uint8_t;
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using u16 = uint16_t;
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using u32 = uint32_t;
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using u64 = uint64_t;
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BAN::Vector<BAN::Vector<char>> parse_grid(FILE* fp)
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{
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BAN::Vector<BAN::Vector<char>> grid;
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char buffer[256];
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while (fgets(buffer, sizeof(buffer), fp))
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{
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BAN::StringView line(buffer);
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ASSERT(line.back() == '\n');
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line = line.substring(0, line.size() - 1);
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if (line.empty())
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break;
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MUST(grid.emplace_back(line.size(), '\0'));
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for (size_t i = 0; i < line.size(); i++)
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grid.back()[i] = line[i];
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}
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return grid;
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}
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struct Position
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{
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i64 x, y;
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Position operator+(const Position& other) const
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{
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return { .x = x + other.x, .y = y + other.y };
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}
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bool operator==(const Position& other) const
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{
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return x == other.x && y == other.y;
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}
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};
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i64 recurse_grid(BAN::Vector<Position>& path, const BAN::Vector<BAN::Vector<char>>& grid)
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{
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const auto entry = path.back();
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BAN::ScopeGuard _([&] { while (path.back() != entry) path.pop_back(); });
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while (path.back().y < (i64)grid.size() - 1)
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{
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BAN::Array<Position, 4> valid_next;
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size_t valid_next_count = 0;
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constexpr Position offsets[4] { { -1, 0 }, { 1, 0 }, { 0, -1 }, { 0, 1 } };
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for (size_t i = 0; i < 4; i++)
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{
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auto next = path.back() + offsets[i];
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if (next.y < 0 || next.y >= (i64)grid.size())
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continue;
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if (next.x < 0 || next.x >= (i64)grid.front().size())
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continue;
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switch (grid[next.y][next.x])
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{
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case '^': next.y--; break;
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case 'v': next.y++; break;
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case '<': next.x--; break;
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case '>': next.x++; break;
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case '#': continue;
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}
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if (path.contains(next))
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continue;
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valid_next[valid_next_count++] = next;
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}
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if (valid_next_count == 0)
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return 0;
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if (valid_next_count == 1)
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{
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MUST(path.push_back(valid_next.front()));
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continue;
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}
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i64 result = 0;
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for (size_t i = 0; i < valid_next_count; i++)
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{
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MUST(path.push_back(valid_next[i]));
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result = BAN::Math::max(result, recurse_grid(path, grid));
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path.pop_back();
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}
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return result;
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}
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i64 result = 0;
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for (size_t i = 1; i < path.size(); i++)
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result += BAN::Math::abs(path[i - 1].x - path[i].x) + BAN::Math::abs(path[i - 1].y - path[i].y);
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return result;
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}
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i64 puzzle1(FILE* fp)
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{
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auto grid = parse_grid(fp);
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BAN::Vector<Position> path;
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for (i64 x = 0; x < (i64)grid.front().size(); x++)
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{
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if (grid.front()[x] == '.')
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{
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MUST(path.push_back({ .x = x, .y = 0 }));
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break;
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}
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}
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return recurse_grid(path, grid);
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}
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i64 puzzle2(FILE* fp)
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{
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(void)fp;
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return -1;
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}
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int main(int argc, char** argv)
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{
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const char* file_path = "/usr/share/aoc2023/day23_input.txt";
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if (argc >= 2)
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file_path = argv[1];
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FILE* fp = fopen(file_path, "r");
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if (fp == nullptr)
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{
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perror("fopen");
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return 1;
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}
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printf("puzzle1: %" PRId64 "\n", puzzle1(fp));
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fseek(fp, 0, SEEK_SET);
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printf("puzzle2: %" PRId64 "\n", puzzle2(fp));
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fclose(fp);
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}
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