adventofcodeday5.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>

struct range_node {
  ulong min;
  ulong max;
  struct range_node *next;
};

int main(void) {
  struct range_node *head = malloc(sizeof(struct range_node));
  struct range_node *current = head;

  FILE *file = fopen("input", "r");
  char *line = malloc(500);
  while (fgets(line, 500, file)) {
    if (line[0] == '\n') {
      break;
    }
    sscanf(line, "%lu-%lu", &current->min, &current->max);
    current->next = malloc(sizeof(struct range_node));
    current = current->next;
  }
  current->next = NULL;

  int sum = 0;
  ulong i;
  while (fscanf(file, "%lu", &i) != EOF) {
    for (struct range_node *node = head; node != NULL; node = node->next) {
      if (i >= node->min && i <= node->max) {
        sum++;
        break;
      }
    }
  }
  printf("Sum is: %d\n", sum);
  fclose(file);
}