Day15
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dobiadi
265
day15/c/day15_part2.c
Normal file
265
day15/c/day15_part2.c
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#include <stdio.h>
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#include <stdlib.h>
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#define MAX_DIMENSION 1024
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#define MAX_MOVES 1024*1024
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typedef enum tile {
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EMPTY,
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WALL,
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BOX,
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ROBOT
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} tile_t;
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typedef struct object {
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tile_t type;
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int pos[2];
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} object_t;
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int can_move(object_t ***map, int rows, int columns, int x, int y, int dir[2]);
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void move(object_t ***map, int rows, int columns, int x, int y, int dir[2]);
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int main() {
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char c;
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object_t ***map = calloc(MAX_DIMENSION, sizeof(map[0]));
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int rows = 0, columns, i = 0;
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map[0] = calloc(MAX_DIMENSION, sizeof(object_t*));
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int reading_map = 1;
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int (*moves)[2] = calloc(MAX_MOVES, sizeof(moves[0]));
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int move_count = 0;
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int robot_pos[2];
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while ((c = getchar()) != EOF) {
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if (reading_map) {
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if (i == 0 && c == '\n') {
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reading_map = 0;
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continue;
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}
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switch (c) {
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case '.':
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{
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object_t *obj = calloc(1, sizeof(obj[0]));
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obj->type = EMPTY;
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obj->pos[0] = rows;
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obj->pos[1] = i;
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map[rows][i] = obj;
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object_t *obj2 = calloc(1, sizeof(obj2[0]));
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obj2->type = EMPTY;
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obj2->pos[0] = rows;
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obj2->pos[1] = ++i;
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map[rows][i] = obj2;
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}
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break;
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case '#':
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{
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object_t *obj = calloc(1, sizeof(obj[0]));
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obj->type = WALL;
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obj->pos[0] = rows;
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obj->pos[1] = i;
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map[rows][i] = obj;
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map[rows][++i] = obj;
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}
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break;
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case 'O':
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{
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object_t *obj = calloc(1, sizeof(obj[0]));
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obj->type = BOX;
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obj->pos[0] = rows;
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obj->pos[1] = i;
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map[rows][i] = obj;
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map[rows][++i] = obj;
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}
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break;
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case '@':
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{
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object_t *obj = calloc(1, sizeof(obj[0]));
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obj->type = ROBOT;
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obj->pos[0] = rows;
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obj->pos[1] = i;
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map[rows][i] = obj;
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robot_pos[0] = rows;
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robot_pos[1] = i;
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object_t *obj2 = calloc(1, sizeof(obj2[0]));
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obj2->type = EMPTY;
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obj2->pos[0] = rows;
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obj2->pos[1] = ++i;
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map[rows][i] = obj2;
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}
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break;
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}
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i++;
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if (c != '\n') {
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continue;
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}
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columns = i - 1;
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i = 0;
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rows++;
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map[rows] = calloc(MAX_DIMENSION, sizeof(object_t*));
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} else {
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switch(c) {
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case '>':
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moves[move_count][0] = 0;
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moves[move_count][1] = 1;
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move_count++;
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break;
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case '<':
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moves[move_count][0] = 0;
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moves[move_count][1] = -1;
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move_count++;
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break;
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case 'v':
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moves[move_count][0] = 1;
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moves[move_count][1] = 0;
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move_count++;
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break;
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case '^':
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moves[move_count][0] = -1;
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moves[move_count][1] = 0;
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move_count++;
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break;
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}
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}
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}
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for (i = 0; i < move_count; i++) {
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if (can_move(map, rows, columns, robot_pos[0], robot_pos[1], moves[i])) {
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move(map, rows, columns, robot_pos[0], robot_pos[1], moves[i]);
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robot_pos[0] += moves[i][0];
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robot_pos[1] += moves[i][1];
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}
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}
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int sum = 0;
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for (i = 0; i < rows; i++) {
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for (int j = 0; j < columns; j++) {
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if (map[i][j]->type == BOX && map[i][j]->pos[0] == i && map[i][j]->pos[1] == j) {
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sum += 100 * i + j;
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}
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}
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}
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for (i = 0; i < rows + 1; i++) {
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free(map[i]);
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}
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free(map);
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free(moves);
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printf("%i\n", sum);
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}
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int can_move(object_t ***map, int rows, int columns, int x, int y, int dir[2]) {
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// Walls cannot move
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if (map[x][y]->type == WALL) {
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return 0;
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}
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// Empty space can be filled
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if (map[x][y]->type == EMPTY) {
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return 1;
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}
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// A box/robot can move if the next tile is movable
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int next_x = x + dir[0];
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int next_y = y + dir[1];
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// Cannot move out of the map although it should not be possible to reach this
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if (next_x < 0 || next_y < 0 || next_x >= rows || next_y >= columns) {
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return 0;
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}
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object_t *next_object = map[next_x][next_y];
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if (next_object->type == WALL) {
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return 0;
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}
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if (next_object->type == BOX) {
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if (next_object->pos[0] != x) {
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return can_move(map, rows, columns, next_object->pos[0], next_object->pos[1], dir) && can_move(map, rows, columns, next_object->pos[0], next_object->pos[1] + 1, dir);
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}
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int can = 1;
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if (map[x][y] != map[next_object->pos[0]][next_object->pos[1]]) {
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can &= can_move(map, rows, columns, next_object->pos[0], next_object->pos[1], dir);
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}
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if (map[x][y] != map[next_object->pos[0]][next_object->pos[1] + 1]) {
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can &= can_move(map, rows, columns, next_object->pos[0], next_object->pos[1] + 1, dir);
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}
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return can;
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}
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return 1;
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}
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void move(object_t ***map, int rows, int columns, int x, int y, int dir[2]) {
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// Walls cannot move
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if (map[x][y]->type == WALL) {
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return;
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}
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// Empty space can be filled
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if (map[x][y]->type == EMPTY) {
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free(map[x][y]);
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return;
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}
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if (map[x][y]->type == BOX) {
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int current_positions[2][2];
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int next_positions[2][2];
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current_positions[0][0] = map[x][y]->pos[0];
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current_positions[0][1] = map[x][y]->pos[1];
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current_positions[1][0] = map[x][y]->pos[0];
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current_positions[1][1] = map[x][y]->pos[1] + 1;
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next_positions[0][0] = current_positions[0][0] + dir[0];
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next_positions[0][1] = current_positions[0][1] + dir[1];
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next_positions[1][0] = current_positions[1][0] + dir[0];
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next_positions[1][1] = current_positions[1][1] + dir[1];
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if (map[x][y] != map[next_positions[0][0]][next_positions[0][1]]) {
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move(map, rows, columns, next_positions[0][0], next_positions[0][1], dir);
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}
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if (map[x][y] != map[next_positions[1][0]][next_positions[1][1]]) {
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move(map, rows, columns, next_positions[1][0], next_positions[1][1], dir);
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}
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// Move current
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map[x][y]->pos[0] = next_positions[0][0];
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map[x][y]->pos[1] = next_positions[0][1];
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map[next_positions[0][0]][next_positions[0][1]] = map[x][y];
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map[next_positions[1][0]][next_positions[1][1]] = map[x][y];
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// Free up positions that were left
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for (int i = 0; i < 2; i++) {
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int left = 1;
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for (int j = 0; j < 2; j++) {
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if (next_positions[j][0] == current_positions[i][0] && next_positions[j][1] == current_positions[i][1]) {
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left = 0;
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break;
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}
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}
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if (left) {
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object_t *obj = calloc(1, sizeof(obj[0]));
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obj->type = EMPTY;
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obj->pos[0] = current_positions[i][0];
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obj->pos[1] = current_positions[i][1];
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map[obj->pos[0]][obj->pos[1]] = obj;
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}
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}
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return;
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}
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// Robot is a single unit
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int next_x = x + dir[0];
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int next_y = y + dir[1];
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move(map, rows, columns, next_x, next_y, dir);
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map[next_x][next_y] = map[x][y];
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object_t *obj = calloc(1, sizeof(obj[0]));
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obj->type = EMPTY;
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obj->pos[0] = x;
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obj->pos[1] = y;
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map[obj->pos[0]][obj->pos[1]] = obj;
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}
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