aoc/src/2021/02.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>

#include "input.h"

static void solution(long p2) {
  size_t sz = 0;
  char **input = get_lines("input/2021/02", &sz);
  long h = 0, d = 0, a = 0;

  for (size_t i = 0; i < sz; ++i) {
    size_t sp_sz = 0;
    char **sp = split(input[i], &sp_sz, " ");
    if (sp == NULL) {
      printf("Failed to split\n");
      exit(1);
    }
    const char *errstr;
    long n = 0;
    n = (long)strtonum(sp[1], LONG_MIN, LONG_MAX, &errstr);
    if (errstr) {
      printf("Failed to convert %s to long\n", sp[i]);
      exit(1);
    }

    if (!p2) {
      if (strcmp("forward", sp[0]) == 0) {
        h += n;
      } else if (strcmp("down", sp[0]) == 0) {
        d += n;
      } else {
        d -= n;
      }
    } else {
      if (strcmp("forward", sp[0]) == 0) {
        h += n;
        d += a * n;
      } else if (strcmp("down", sp[0]) == 0) {
        a += n;
      } else {
        a -= n;
      }
    }
    free(sp);
  }
  printf("%ld\n", h * d);
  del_lines(input);
}

void advent2021day02(void) {
  solution(0);
  solution(1);
}