aoc

Advent of Code challenges
log files refs
aoc_2024_2_1.c (1367B)
      1#include <stdio.h>
      2#include <stdlib.h>
      3#include <stdbool.h>
      4#include <string.h>
      5#include <ctype.h>
      6
      7#define ROW_SIZE 50
      8
      9typedef enum {
     10  DIR_NIL = 0,
     11  DIR_INC = 1,
     12  DIR_DEC = 2,
     13} dir_t;
     14
     15long perform(char *data) {
     16  int len = strlen(data);
     17  int ln = 0;
     18  int sum = 0;
     19  int size = 0;
     20  int row[ROW_SIZE];
     21  for (int i = 0; i < len;) {
     22    char c = data[i];
     23    if (isdigit(c)) {
     24      char *end = NULL;
     25      row[size++] = strtol(data + i, &end, 10);
     26      i += end - (data + i);
     27      continue;
     28    }
     29    if (c == '\n') {
     30      bool unsafe = false;
     31      int *prev = NULL;
     32      dir_t dir = DIR_NIL;
     33      for (int j = 0; j < size; j++) {
     34        int *num = &row[j];
     35        if (prev != NULL) {
     36          // check 1. criteria
     37          dir_t next_dir = DIR_NIL;
     38          if (*num > *prev) {
     39            next_dir = DIR_INC;
     40          }
     41          if (*num < *prev) {
     42            next_dir = DIR_DEC;
     43          }
     44          if (dir != DIR_NIL && next_dir != dir) {
     45            unsafe = true;
     46            break;
     47          }
     48          dir = next_dir;
     49          // check 2. criteria
     50          int delta = abs(*num - *prev);
     51          if (delta == 0 || delta > 3) {
     52            unsafe = true;
     53            break;
     54          }
     55        }
     56        prev = num;
     57      }
     58      if (!unsafe) {
     59        sum++;
     60      }
     61      size = 0;
     62      ln++;
     63    }
     64    i++;
     65  }
     66  return sum;
     67}