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Day16 C

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dobiadi
2023-12-19 19:21:17 +01:00
parent fe918ad8e3
commit d07adb1b15
4 changed files with 328 additions and 0 deletions
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define LINE_MAX_LENGTH 256
typedef enum tile_type {
EMPTY,
MIRROR_LEFT_TO_UP,
MIRROR_LEFT_TO_DOWN,
SPLITTER_VERTICAL,
SPLITTER_HORIZONTAL,
} tile_type_t;
typedef enum light_direction {
LEFT_TO_RIGHT,
RIGHT_TO_LEFT,
UP_TO_DOWN,
DOWN_TO_UP,
} light_direction_t;
typedef struct tile {
tile_type_t type;
light_direction_t lights[4];
int lights_num;
} tile_t;
void traverse_light(tile_t map[LINE_MAX_LENGTH][LINE_MAX_LENGTH], int x, int y, int entry_x, int entry_y, int dir[2]);
int has_light(tile_t map[LINE_MAX_LENGTH][LINE_MAX_LENGTH], int x, int y, light_direction_t direction, int max_x, int max_y);
light_direction_t dir_to_direction(int dir[2]);
int count_energized(tile_t map[LINE_MAX_LENGTH][LINE_MAX_LENGTH], int x, int y);
int main() {
char *p, *buf, c;
buf = (char *)malloc(LINE_MAX_LENGTH);
memset(buf, 0, LINE_MAX_LENGTH);
p = buf;
tile_t map[LINE_MAX_LENGTH][LINE_MAX_LENGTH];
memset(map, 0, LINE_MAX_LENGTH * LINE_MAX_LENGTH * sizeof(tile_t));
int x = 0, y = 0;
while ((c = getchar()) != EOF) {
*p++ = c;
if (c == '\n') {
p = buf;
x = 0;
while (*p != '\n') {
switch (*p) {
case '.':
map[x][y].type = EMPTY;
break;
case '/':
map[x][y].type = MIRROR_LEFT_TO_UP;
break;
case '\\':
map[x][y].type = MIRROR_LEFT_TO_DOWN;
break;
case '|':
map[x][y].type = SPLITTER_VERTICAL;
break;
case '-':
map[x][y].type = SPLITTER_HORIZONTAL;
break;
}
x++;
p++;
}
y++;
memset(buf, 0, LINE_MAX_LENGTH);
p = buf;
}
}
tile_t map_cpy[LINE_MAX_LENGTH][LINE_MAX_LENGTH];
memcpy(map_cpy, map, LINE_MAX_LENGTH * LINE_MAX_LENGTH * sizeof(tile_t));
int dir[2] = {1, 0};
traverse_light(map_cpy, x, y, -1, 0, dir);
int part1 = count_energized(map_cpy, x, y);
int max_energized = 0, energized;
// LEFT COLUMN
for (int i = 0; i < y; i++) {
dir[0] = 1;
dir[1] = 0;
memcpy(map_cpy, map, LINE_MAX_LENGTH * LINE_MAX_LENGTH * sizeof(tile_t));
traverse_light(map_cpy, x, y, -1, i, dir);
energized = count_energized(map_cpy, x, y);
if (energized > max_energized) {
max_energized = energized;
}
}
// RIGHT COLUMN
for (int i = 0; i < y; i++) {
dir[0] = -1;
dir[1] = 0;
memcpy(map_cpy, map, LINE_MAX_LENGTH * LINE_MAX_LENGTH * sizeof(tile_t));
traverse_light(map_cpy, x, y, x, i, dir);
energized = count_energized(map_cpy, x, y);
if (energized > max_energized) {
max_energized = energized;
}
}
// TOP ROW
for (int i = 0; i < x; i++) {
dir[0] = 0;
dir[1] = 1;
memcpy(map_cpy, map, LINE_MAX_LENGTH * LINE_MAX_LENGTH * sizeof(tile_t));
traverse_light(map_cpy, x, y, i, -1, dir);
energized = count_energized(map_cpy, x, y);
if (energized > max_energized) {
max_energized = energized;
}
}
// BOTTOM ROW
for (int i = 0; i < x; i++) {
dir[0] = 0;
dir[1] = -1;
memcpy(map_cpy, map, LINE_MAX_LENGTH * LINE_MAX_LENGTH * sizeof(tile_t));
traverse_light(map_cpy, x, y, i, y, dir);
energized = count_energized(map_cpy, x, y);
if (energized > max_energized) {
max_energized = energized;
}
}
printf("%i\n", part1);
printf("%i\n", max_energized);
free(buf);
}
void traverse_light(tile_t map[LINE_MAX_LENGTH][LINE_MAX_LENGTH], int x, int y, int entry_x, int entry_y, int dir[2]) {
light_direction_t curr_direction = dir_to_direction(dir);
int curr_x = entry_x, curr_y = entry_y;
while (!has_light(map, curr_x + dir[0], curr_y + dir[1], curr_direction, x - 1, y - 1)) {
curr_x += dir[0];
curr_y += dir[1];
map[curr_x][curr_y].lights[map[curr_x][curr_y].lights_num] = curr_direction;
map[curr_x][curr_y].lights_num++;
if (map[curr_x][curr_y].type == MIRROR_LEFT_TO_UP) {
int tmp = dir[0];
dir[0] = -dir[1];
dir[1] = -tmp;
} else if (map[curr_x][curr_y].type == MIRROR_LEFT_TO_DOWN) {
int tmp = dir[0];
dir[0] = dir[1];
dir[1] = tmp;
} else if (map[curr_x][curr_y].type == SPLITTER_HORIZONTAL && dir[1] != 0) {
dir[0] = 1;
dir[1] = 0;
int recurse_dir[2] = {-1, 0};
traverse_light(map, x, y, curr_x, curr_y, recurse_dir);
} else if (map[curr_x][curr_y].type == SPLITTER_VERTICAL && dir[0] != 0) {
dir[0] = 0;
dir[1] = 1;
int recurse_dir[2] = {0, -1};
traverse_light(map, x, y, curr_x, curr_y, recurse_dir);
}
curr_direction = dir_to_direction(dir);
}
}
int has_light(tile_t map[LINE_MAX_LENGTH][LINE_MAX_LENGTH], int x, int y, light_direction_t direction, int max_x, int max_y) {
if (x < 0 || y < 0 || x > max_x || y > max_y) {
return 1;
}
for (int i = 0; i < map[x][y].lights_num; i++) {
if (map[x][y].lights[i] == direction) {
return 1;
}
}
return 0;
}
light_direction_t dir_to_direction(int dir[2]) {
if (dir[0] == 1) {
return LEFT_TO_RIGHT;
} else if (dir[0] == -1) {
return RIGHT_TO_LEFT;
} else if (dir[1] == 1) {
return UP_TO_DOWN;
}
return DOWN_TO_UP;
}
int count_energized(tile_t map[LINE_MAX_LENGTH][LINE_MAX_LENGTH], int x, int y) {
int sum = 0;
for (int i = 0; i < y; i++) {
for (int j = 0; j < x; j++) {
if (map[j][i].lights_num > 0) {
sum++;
}
}
}
return sum;
}