AdventOfCode/2024/c/Day_2/main.c

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

#define IMP
#include "../file.h"

struct report {
	size_t cap;
	size_t size;
	long *data;
};


size_t cstr_char_count(const char *cstr, char c);
int cmp_sort(const void *this, const void *other);

int
main(int argc, char *argv[])
{
	enum file_err ferr;
	size_t line_num = 0;
	size_t i = 0;
	long res = 0;

	struct report *reports = NULL;
	size_t reports_size = 0;

	char *raw_input = NULL;
	size_t raw_input_size = 0;
	raw_input = (char *) file_read_all("./input.txt", 
					   &raw_input_size,
					   &ferr);
	if ( ferr != FILE_ERR_OK ) {
		fprintf(stderr, "Failed to open file: %s\n", 
			file_err_to_cstr(ferr));
		exit(EXIT_FAILURE);
	}

	line_num = cstr_char_count(raw_input, '\n');

	reports = calloc(line_num+1, sizeof(*reports));

	{
	long ret = -1;
	char *str = raw_input;
	char *nstr = NULL;
	struct report *this = &reports[reports_size++];
	if ( this->data == NULL ) {
		this->cap = 10;
		this->size = 0;
		this->data = calloc(this->cap, sizeof(*this->data));
	}

	while ( true ) {
		ret = strtol(str, &nstr, 10);
		if ( ret == 0 ) {
			break;
		}
		str = nstr;

		if ( this->size+1 >= this->cap ) {
			this->cap <<= 1;
			this->data = realloc(this->data, this->cap * sizeof(*this->data));
		}
		this->data[this->size++] = ret;

		if ( *str == '\n' ) {
			this = &reports[reports_size++];
			if ( this->data == NULL ) {
				this->cap = 10;
				this->size = 0;
				this->data = calloc(this->cap, sizeof(*this->data));
			}
		}
	}
	}

	if ( argc == 1 ) {
		for ( i = 0; i < reports_size; ++i ) {
			size_t j = 1;
			struct report *this = &reports[i];
			long dir = this->data[0] - this->data[1];
			if ( dir == 0 ) {
				/* if dir is == 0 it is already unsafe */
				continue;
			}

			++res;
			for ( j = 1; j < this->size; ++j ) {
				long diff = this->data[j-1] - this->data[j];
				long diff_abs = labs(diff);

				if ( diff_abs < 1 || diff_abs > 3 ) {
					--res;
					break;
				}

				if ( ( diff > 0 && dir < 0 ) || ( diff < 0 && dir > 0 ) ) {
					--res;
					break;
				}
			}
		}
	} else {
	}


	printf("Result: %ld\n", res);

	for ( i = 0; i < reports_size; ++i ) {
		free(reports[i].data);
	}

	free(reports);

	free(raw_input);

	(void) argc; (void) argv;
	return 0;
}

size_t 
cstr_char_count(const char *cstr, char c)
{
	size_t ret = 0;
	while ( *cstr != '\0' ) {
		ret += ( *cstr == c );
		cstr++;
	}
	return ret;
}

int 
cmp_sort(const void *this, const void *other)
{
	long this_ = *((long*) this);
	long other_ = *((long*) other);

	return (int) (this_ - other_);
}