Day 2: Red-Nosed Reports

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[-] sjmulder@lemmy.sdf.org 5 points 2 years ago

C

First went through the input in one pass, number by number, but unfortunately that wouldn't fly for part 2.

Code

#include "common.h"

static int
issafe(int *lvs, int n, int skip)
{
	int safe=1, asc=0,prev=0, ns=0,i;

	for (i=0; safe && i<n; i++) {
		if (i == skip)
			{ ns = 1; continue; }
		if (i-ns > 0)
			safe = safe && lvs[i] != prev &&
			    lvs[i] > prev-4 && lvs[i] < prev+4;
		if (i-ns == 1)
			asc = lvs[i] > prev;
		if (i-ns > 1)
			safe = safe && (lvs[i] > prev) == asc;

		prev = lvs[i];
	}

	return safe;
}

int
main(int argc, const char **argv)
{
	char buf[64], *rest, *tok;
	int p1=0,p2=0, lvs[16],n=0, i;

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

	while ((rest = fgets(buf, sizeof(buf), stdin))) {
		for (n=0; (tok = strsep(&rest, " ")); n++) {
			assert(n < (int)LEN(lvs));
			lvs[n] = (int)strtol(tok, NULL, 10);
		}

		for (i=-1; i<n; i++)
			if (issafe(lvs, n, i))
				{ p1 += i == -1; p2++; break; }
	}

	printf("02: %d %d\n", p1, p2);
}

https://github.com/sjmulder/aoc/blob/master/2024/c/day02.c

[-] Faresh@lemmy.ml 2 points 2 years ago

What is this coding style? The function type, name and open brace placement made me think GNU at first, but the code in the body doesn't look like GCS at all.

[-] sjmulder@lemmy.sdf.org 2 points 2 years ago

BSD more or less. Mostly K&R except for function declarations.

this post was submitted on 02 Dec 2024

44 points (97.8% liked)

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