this post was submitted on 19 Dec 2024
8 points (78.6% liked)

Advent Of Code

1222 readers
1 users here now

An unofficial home for the advent of code community on programming.dev! Other challenges are also welcome!

Advent of Code is an annual Advent calendar of small programming puzzles for a variety of skill sets and skill levels that can be solved in any programming language you like.

Everybody Codes is another collection of programming puzzles with seasonal events.

EC 2025

AoC 2025

Solution Threads

M T W T F S S
1 2 3 4 5 6 7
8 9 10 11 12

Visualisations Megathread

Rules/Guidelines

Relevant Communities

Relevant Links

Credits

Icon base by Lorc under CC BY 3.0 with modifications to add a gradient

console.log('Hello World')

founded 2 years ago
MODERATORS
 

Day 19 - Linen Layout

Megathread guidelines

  • Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
  • You can send code in code blocks by using three backticks, the code, and then three backticks or use something such as https://topaz.github.io/paste/ if you prefer sending it through a URL

FAQ

you are viewing a single comment's thread
view the rest of the comments
[โ€“] sjmulder@lemmy.sdf.org 2 points 1 year ago

C

Interestingly part 1 already defied a naive approach. It was fun thinking of a way to memoize without hash tables.

Code

#include "common.h"

static char *pats[480];
static int lens[480];
int np;

/* memoized for 's' by mem[off], 0 = unknown, >0 = value+1 */
static int64_t
recur(char *s, int off, int64_t *mem)
{
	int64_t acc=0;
	int i;

	if (!s[off]) return 1;
	if (mem[off]) return mem[off]-1;

	for (i=0; i<np; i++)
		if (!strncmp(s+off, pats[i], lens[i]))
			acc += recur(s, off+lens[i], mem);

	mem[off] = acc+1;
	return acc;
}

int
main(int argc, char **argv)
{
	static char patbuf[3200], design[64];
	int64_t p1=0,p2=0, mem[64], n;
	char *rest, *lf;

	if (argc > 1)
		DISCARD(freopen(argv[1], "r", stdin));

	rest = fgets(patbuf, sizeof(patbuf), stdin);

	for (; (pats[np] = strsep(&rest, ",")); np++) {
		while (isspace(pats[np][0]))
			pats[np]++;	/* skip spaces */
		if ((lf = strchr(pats[np], '\n')))
			*lf = '\0';	/* trim trailing \n */
		lens[np] = strlen(pats[np]);
		assert(np+1 < (int)LEN(pats));
	}

	while (scanf(" %63s", design) == 1) {
		memset(mem, 0, sizeof(mem));
		n = recur(design, 0, mem);
		p1 += n >0;
		p2 += n;
	}

	printf("19: %"PRId64" %"PRId64"\n", p1, p2);
	return 0;
}

https://codeberg.org/sjmulder/aoc/src/branch/master/2024/c/day19.c

Zee

Also a port to my cursed Dutch dialect of C, Zee:

Code

#ingesloten "zee.kop"
#ingesloten "algemeen.kop"

besloten letterverwijzing patronen[480];
besloten getal lengtes[480];
getal patroonsom;

besloten zeer groot getal
afdaling(
    letterverwijzing tekst,
    getal startpositie,
    zeergrootgetalreeksverwijzing onthouden)
{
	zeer groot getal deelsom=0;
	getal sortering, teller;

	tenzij (tekst[startpositie])
		lever 1;
	mits (onthouden[startpositie])
		lever onthouden[startpositie]-1;

	voor (teller=0; teller < patroonsom; teller++) {
		sortering = tekstdeelvergelijking(
		    tekst + startpositie,
		    patronen[teller],
		    lengtes[teller]);

		mits (sortering == 0) {
			deelsom += afdaling(
			    tekst,
			    startpositie + lengtes[teller],
			    onthouden);
		}
	}

	onthouden[startpositie] = deelsom+1;
	lever deelsom;
}

getal
aanvang(
    getal parametersom,
    letterverwijzingsreeksverwijzing parameters)
{
	blijvende letter patroonruimte[3200];
	blijvende letter ontwerp[64];
	zeer groot getal deel1=0, aantal;
	zeer groot getal deel2=0, onthouden[64];
	letterverwijzing rest;
	letterverwijzing regeleinde;

	mits (parametersom > 1)
		VERWERP(heropen(parameters[1], "r", standaardinvoer));

	rest = geefregel(patroonruimte, grootte(patroonruimte),
	    standaardinvoer);

	voor (; ; patroonsom++) {
		verzeker(patroonsom+1 < (getal)LENGTE(patronen));
		patronen[patroonsom] = tekstsplitsing(naar rest, ",");
		mits (patronen[patroonsom] == NIETS)
			klaar;

		zolang (iswitruimte(patronen[patroonsom][0]))
			patronen[patroonsom]++;
		mits ((regeleinde = zoekletter(patronen[patroonsom], '\n')))
			volg regeleinde = '\0';

		lengtes[patroonsom] = tekstlengte(patronen[patroonsom]);
	}

	zolang (invorm(" %63s", ontwerp) == 1) {
		overschrijf(onthouden, 0, grootte(onthouden));
		aantal = afdaling(ontwerp, 0, onthouden);
		deel1 += aantal >0;
		deel2 += aantal;
	}

	uitvorm("19: %"GEEFZGG" %"GEEFZGG"\n", deel1, deel2);
	lever 0;
}

https://codeberg.org/sjmulder/aoc/src/