79 lines
1.8 KiB
C
79 lines
1.8 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdbool.h>
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#include "../../lib/aoc.h"
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#define WIDTH 101
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#define HEIGHT 103
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#define CYCLES 100
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typedef struct Robot {
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int px;
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int py;
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int vx;
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int vy;
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} Robot;
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int main() {
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char *line;
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int px, py, vx, vy;
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int q1 = 0, q2 = 0, q3 = 0, q4 = 0;
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Robot robots[500];
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int robots_count = 0;
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while((line = aoc_read_line()) != NULL) {
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sscanf(line, "p=%d,%d v=%d,%d", &px, &py, &vx, &vy);
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robots[robots_count].px = px;
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robots[robots_count].py = py;
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robots[robots_count].vx = vx;
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robots[robots_count].vy = vy;
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robots_count++;
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}
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char blank_map[((WIDTH + 1) * HEIGHT) + 1];
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for (int i = 0; i < (WIDTH + 1) * HEIGHT; i++) {
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blank_map[i] = i % (WIDTH + 1) == WIDTH ? '\n' : '.';
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}
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char map[((WIDTH + 1) * HEIGHT) + 1];
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// Isn't it lovely?
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char *christmas_tree = "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX";
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int i;
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for (i = 0; ; i++) {
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strcpy(map, blank_map);
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for (int j = 0; j < robots_count; j++) {
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map[robots[j].px + (robots[j].py * (WIDTH + 1))] = 'X';
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robots[j].px += robots[j].vx;
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robots[j].px = (robots[j].px + WIDTH) % WIDTH;
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robots[j].py += robots[j].vy;
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robots[j].py = (robots[j].py + HEIGHT) % HEIGHT;
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}
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if (strstr(map, christmas_tree) != NULL) break;
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if (i == CYCLES - 1) {
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for (int j = 0; j < robots_count; j++) {
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Robot r = robots[j];
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if (r.px < WIDTH / 2 && r.py < HEIGHT / 2) q1++;
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if (r.px > WIDTH / 2 && r.py < HEIGHT / 2) q2++;
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if (r.px < WIDTH / 2 && r.py > HEIGHT / 2) q3++;
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if (r.px > WIDTH / 2 && r.py > HEIGHT / 2) q4++;
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}
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}
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}
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// Uncomment this to print the pretty christmas tree
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// printf("%s\n", map);
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printf("Part 1: %d\n", q1 * q2 * q3 * q4);
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printf("Part 2: %d\n", i);
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aoc_free();
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return 0;
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}
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