forked from Bananymous/banan-os
153 lines
3.0 KiB
C++
153 lines
3.0 KiB
C++
#include <BAN/Array.h>
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#include <BAN/Vector.h>
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#include <fcntl.h>
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#include <inttypes.h>
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#include <stdio.h>
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#include <sys/framebuffer.h>
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#include <sys/mman.h>
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#include <termios.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 isize = ssize_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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using usize = size_t;
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i64 part1(FILE* fp)
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{
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i32 quadrants[4] {};
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for (;;)
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{
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i32 px, py, vx, vy;
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if (fscanf(fp, "p=%" SCNd32 ",%" SCNd32 " v=%" SCNd32 ",%" SCNd32 "\n", &px, &py, &vx, &vy) != 4)
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break;
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const i32 tx = (((px + 100 * vx) % 101) + 101) % 101;
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const i32 ty = (((py + 100 * vy) % 103) + 103) % 103;
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if (tx < 50 && ty < 51)
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quadrants[0]++;
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if (tx > 50 && ty < 51)
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quadrants[1]++;
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if (tx < 50 && ty > 51)
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quadrants[2]++;
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if (tx > 50 && ty > 51)
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quadrants[3]++;
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}
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return quadrants[0] * quadrants[1] * quadrants[2] * quadrants[3];
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}
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struct Robot
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{
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i32 px, py;
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i32 vx, vy;
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};
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usize largest_area(const BAN::Vector<Robot>& robots)
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{
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BAN::Array<bool, 101 * 103> robot_map(false);
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for (const auto& robot : robots)
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robot_map[robot.py * 101 + robot.px] = true;
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BAN::Array<bool, 101 * 103> checked(false);
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usize result = 0;
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for (i32 y = 0; y < 103; y++)
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{
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for (i32 x = 0; x < 101; x++)
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{
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if (checked[y * 101 + x])
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continue;
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if (!robot_map[y * 101 + x])
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continue;
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struct Position { i32 x, y; };
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BAN::Vector<Position> to_check;
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MUST(to_check.reserve(101 * 103));
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MUST(to_check.emplace_back(x, y));
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usize area = 0;
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while (!to_check.empty())
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{
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const auto pos = to_check.back();
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to_check.pop_back();
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if (checked[pos.y * 101 + pos.x])
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continue;
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checked[pos.y * 101 + pos.x] = true;
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if (!robot_map[pos.y * 101 + pos.x])
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continue;
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area++;
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if (pos.x - 1 >= 0) MUST(to_check.emplace_back(pos.x - 1, pos.y ));
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if (pos.x + 1 < 101) MUST(to_check.emplace_back(pos.x + 1, pos.y ));
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if (pos.y - 1 >= 0) MUST(to_check.emplace_back(pos.x, pos.y - 1));
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if (pos.y + 1 < 103) MUST(to_check.emplace_back(pos.x, pos.y + 1));
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}
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result = BAN::Math::max(result, area);
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}
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}
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return result;
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}
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i64 part2(FILE* fp)
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{
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BAN::Vector<Robot> robots;
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for (;;)
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{
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i32 px, py, vx, vy;
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if (fscanf(fp, "p=%" SCNd32 ",%" SCNd32 " v=%" SCNd32 ",%" SCNd32 "\n", &px, &py, &vx, &vy) != 4)
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break;
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MUST(robots.emplace_back(px, py, vx, vy));
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}
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for (i64 frame = 0;; frame++)
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{
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if (largest_area(robots) >= robots.size() / 4)
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return frame;
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for (auto& robot : robots)
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{
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robot.px = (((robot.px + robot.vx) % 101) + 101) % 101;
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robot.py = (((robot.py + robot.vy) % 103) + 103) % 103;
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}
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}
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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/aoc2024/day14_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("part1: %" PRId64 "\n", part1(fp));
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fseek(fp, 0, SEEK_SET);
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printf("part2: %" PRId64 "\n", part2(fp));
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fclose(fp);
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}
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