c 2024 day 10 part 1

c/2024/10/hoof_it.c

@@ -0,0 +1,80 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+
+#include "../../lib/aoc.h"
+
+typedef struct Map {
+  char *data;
+  int data_length;
+  int width;
+  int height;
+  int current_level;
+  int positions[10000];
+  int positions_count;
+} Map;
+
+void ascend(Map *map) {
+  char search_for = map->current_level + 1 + '0';
+  int positions[10000];
+  int positions_count = 0;
+  for (int i = 0; i < map->positions_count; i++) {
+    int p = map->positions[i];
+    if (p - map->width >= 0 && map->data[p - map->width] == search_for) positions[positions_count++] = p - map->width;
+    if (map->data[p - 1] == search_for) positions[positions_count++] = p - 1;
+    if (map->data[p + 1] == search_for) positions[positions_count++] = p + 1;
+    if (p + map->width < map->data_length && map->data[p + map->width] == search_for) positions[positions_count++] = p + map->width;
+  }
+
+  qsort(positions, positions_count, sizeof(int), aoc_sort_int);
+
+  int deduped_positions[10000];
+  int deduped_positions_count = 0;
+
+  for (int i = 0; i < positions_count - 1; i++) {
+    if (positions[i] != positions[i+1]) {
+      deduped_positions[deduped_positions_count++] = positions[i];
+    }
+  }
+  deduped_positions[deduped_positions_count++] = positions[positions_count - 1];
+
+  map->positions_count = deduped_positions_count;
+  memcpy(&(map->positions), &deduped_positions, deduped_positions_count * sizeof(int));
+  map->current_level++;
+}
+
+int calculate_score(Map *map, int index) {
+  if (map->data[index] != '0') return 0;
+  map->current_level = 0;
+
+  map->positions[0] = index; 
+  map->positions_count = 1;
+  for (int i = 0; i < 9; i++) {
+    ascend(map);
+  }
+  return map->positions_count;
+}
+
+int main() {
+  char *input = aoc_read_input();
+  int input_length = strlen(input);
+
+  Map m;
+  m.data = input;
+  m.data_length = input_length;
+  m.width = strchr(input, '\n') - input + 1;
+  m.height = input_length - m.width;
+
+  int score = 0;
+
+  for (int i = 0; i < input_length; i++) {
+    score += calculate_score(&m, i);
+  }
+
+  printf("Part 1: %ld\n", score);
+  // printf("Part 2: %ld\n", second_checksum);
+  
+  aoc_free();
+  return 0;
+}