advent_of_code/day_2/1.c
2024-12-08 17:15:12 -07:00

72 lines
1.3 KiB
C

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#define BUFFER_SIZE 1024
typedef struct levels {
size_t mem_size;
size_t size;
int *data;
} levels_t;
int main(void) {
FILE *fp = fopen("input", "r");
if (fp == NULL) {
perror("input");
return 1;
}
char buffer[BUFFER_SIZE];
levels_t levels;
levels.mem_size = 10;
levels.size = 0;
levels.data = malloc(sizeof(unsigned int) * levels.mem_size);
unsigned int sum = 0;
while (fgets(buffer, BUFFER_SIZE, fp) != NULL) {
char *next = strtok(buffer, " ");
while (next != NULL) {
if (levels.size >= levels.mem_size) {
levels.mem_size *= 2;
levels.data =
realloc(levels.data, levels.mem_size * sizeof(unsigned int));
}
sscanf(next, "%d", &levels.data[levels.size]);
levels.size++;
next = strtok(NULL, " ");
}
bool safe = true;
int diff = levels.data[1] - levels.data[0];
int increasing = diff > 0 ? 1 : -1;
for (size_t i = 1; i < levels.size; i++) {
diff = increasing * (levels.data[i] - levels.data[i - 1]);
if (diff < 1 || diff > 3) {
safe = false;
break;
}
}
if (safe) {
sum++;
}
levels.size = 0;
}
free(levels.data);
printf("%u\n", sum);
fclose(fp);
return 0;
}