advent-of-code/2022/1.c

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

int comp(const void *a, const void *b) {
  int n = *(int *)a;
  int m = *(int *)b;
  return n - m;
}

int main(int argc, char *argv[]) {

  if (argc != 2) {
    fprintf(stderr, "USAGE: %s input_file\n", argv[0]);
    return 1;
  }

  FILE *fd = fopen(argv[1], "r");
  if (!fd) {
    fprintf(stderr, "Error opening file\n");
    return 1;
  }

  char line[50] = {0};
  int idx = 0, elves[1000] = {0};

  while (fgets(line, sizeof line / sizeof *line, fd) != NULL) {
    if (strlen(line) == 1) {
      idx++;
    } else {
      elves[idx] += atoi(line);
    }
  }

  qsort(elves, idx, sizeof(int), comp);

  printf("Elf with the most calories:     %d\n", elves[idx - 1]);
  printf("Elf with the 2nd most calories: %d\n", elves[idx - 2]);
  printf("Elf with the 3rd most calories: %d\n", elves[idx - 3]);
  printf("Total:                          %d\n",
         elves[idx - 1] + elves[idx - 2] + elves[idx - 3]);

  fclose(fd);
  return 0;
}