2011-day13.c

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

enum TYPE
{
	NUM,
	SET
};

struct set
{
	int count;
	struct set *parent;
	struct node *n[32];
};

struct node
{
	int type;
	union {
		int num;
		struct set *set;
	};
};

static void set_add_set(struct set *s, struct set *n)
{
	int i;

	i = s->count++;

	s->n[i] = malloc(sizeof (struct node));

	s->n[i]->type = SET;
	s->n[i]->set = n;
}

static void set_add_num(struct set *s, int n)
{
	int i;

	i = s->count++;

	s->n[i] = malloc(sizeof (struct node));

	s->n[i]->type = NUM;
	s->n[i]->num = n;
}

static struct set *parse(char **s, struct set *parent)
{
	struct set *n;

	n = calloc(1, sizeof (struct set));
	n->count = 0;
	n->parent = parent;

	while(**s && **s != '\n')
	{
		if(**s == ']')
		{
			(*s)++;
			break;
		}

		if(**s == '[')
		{
			(*s)++;
			set_add_set(n, parse(s, n));
			continue;
		}

		if(**s == ',')
		{
			(*s)++;
			continue;
		}
		if(**s >= '0' && **s <= '9')
		{
			set_add_num(n, strtol(*s, s, 10));

		}
	}


	return n;
}

static void dump_set(struct set *s);

static void dump_node(struct node *n)
{
	if(n->type == NUM)
	{
		printf("%d", n->num);
	} else {
		dump_set(n->set);
	}
}

static void dump_set(struct set *s)
{
	int i = 0;
	struct node *n;

	putchar('[');

	for(i = 0; i < s->count; i++)
	{
		dump_node(s->n[i]);
		if(s->n[i+1])
			printf(", ");
	}

	putchar(']');
}

static int compare(struct set *s1, struct set *s2)
{
	int i;
	int left, right;

	i = 0;

	if(!s1)
		return 1;
	if(!s2)
		return 0;

	printf("s1: %d, s2: %d\n", s1->count, s2->count);

	while(1)
	{
		if(i >= s1->count)
			break;
		if(i >= s2->count)
			return 0;
		if(s1->n[i]->type == NUM && s2->n[i]->type == NUM)
		{
			printf("Comparing %d vs %d\n", s1->n[i]->num, s2->n[i]->num);
			if(s1->n[i]->num > s2->n[i]->num)
				return 0;
		}
		else if(s1->n[i]->type == SET && s2->n[i]->type)
		{
			if(compare(s1->n[i]->set, s2->n[i]->set) == 0)
			{
				return 0;
			}
		}
		else if(s1->n[i]->type == NUM && s2->n[i]->type == SET)
		{
			if(!s2->n[i]->set->count || s2->n[i]->set->n[0]->type == SET)
			{
				if(compare(s1, s2->n[i]->set) == 0)
					return 0;
			}else 
			if(s1->n[i]->num > s2->n[i]->set->n[0]->num)
				return 0;
		}
		else if(s1->n[i]->type == SET && s2->n[i]->type == NUM)
		{
			if(!s1->n[i]->set->count || s1->n[i]->set->n[0]->type == SET)
			{
				if(compare(s1->n[i]->set, s2) == 0)
					return 0;
			} else 
			if(s1->n[i]->set->n[0]->num > s2->n[i]->num)
				return 0;
		}

		i++;
	}

	return 1;
}

int main(void)
{
	char line1[1024], line2[1024];
	
	FILE *f;

	f = fopen("day13.txt", "r");
	int i = 1;
	int sum = 0;

	while(1)
	{
		struct set *set1, *set2;
		char *p1, *p2;

		if(!fgets(line1, 1024, f))
			break;
		fgets(line2, 1024, f);
		line1[strlen(line1)-1] = 0;
		line2[strlen(line2)-1] = 0;

		p1 = line1;
		p2 = line2;

		set1 = parse(&p1, NULL);
		set2 = parse(&p2, NULL);

		dump_set(set1);
		putchar('\n');
		dump_set(set2);
		putchar('\n');

		int r = compare(set1, set2);
		printf("\t\tResult: %d\n", r);

		if(r)
			sum += i;


		i++;
		/* Eat the newline between pairs */
		if(!fgets(line1, 1024, f))
			break;
	}

	printf("sum: %d\n", sum);

	return 0;
}