2022-day5.c

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

struct col {
	char v;
	struct col *next;
};

static struct col *newc(char v)
{
	struct col *c = malloc(sizeof *c);

	c->v = v;
	c->next = NULL;

	return c;
}

static void append(struct col **c, char v)
{
	struct col *t, **at;

	for(at = c; *at; at = &((*at)->next))
		;

	t = newc(v);
	t->next = NULL;

	*at = t;
}

static void move(struct col **d, struct col **s)
{
	struct col *t;

	t = *s;
	*s = (*s)->next;

	t->next = *d;
	*d = t;
}

static void move2(struct col **d, struct col **s, int count)
{
	struct col *t, *t2;
	int i;

	t = *s;
	t2 = *s;

	for(i = 0; i < count; i++)
		*s = (*s)->next;

	for(i = 0; i < count-1; i++)
		t2 = t2->next;

	t2->next = *d;

	*d = t;
}

static void dumpcol(struct col *c)
{
	struct col *t;

	for(t = c; t; t = t->next)
		printf("%c -> ", t->v);
	puts("NULL");
}

int main(void)
{
	char line[1024];
	FILE *f;
	int r;

	f = fopen("day5.txt", "r");

	struct col *c[9] = {0};

	for(r = 0; r < 8; r++)
	{
		int i;

		if(!fgets(line, 128, f))
			break;

		for(i = 0; i < 9; i++)
		{
			char v = line[i*4+1];

			putchar(v);
			if(v == ' ')
				continue;

			append(&c[i], v);
		}
		putchar('\n');
	}

	for(r = 0; r < 9; r++)
		dumpcol(c[r]);

	printf("Following commands...\n");

	fgets(line, 128, f);
	fgets(line, 128, f);

	while(1)
	{
		int count, from, to;

		if(!fgets(line, 128, f))
			break;

		sscanf(line, "move %d from %d to %d\n", &count, &from, &to);

		to--;
		from--;

		printf("\n\nMove %d from %d to %d\n", count, from+1, to+1);

#ifdef P1
		for(r = 0; r < count; r++)
			move(&c[to], &c[from]);
#else
		if(count != 1)
			move2(&c[to], &c[from], count);
		else
			move(&c[to], &c[from]);
#endif

		for(r = 0; r < 9; r++)
			dumpcol(c[r]);

		printf("Moved %d from %d to %d\n", count, from+1, to+1);
	}

	for(r = 0; r < 8; r++)
	{
		putchar(c[r]->v);
	}
	putchar('\n');

	return 0;
}