… oh well, it had to come to this

2024/11/s1

+#!/bin/lksh
+# might need LP64
+
+set -o noglob +o posix
+IFS=' '
+set -A x -- $(<inputfile)
+n=-1
+while (( ++n < 25 )); do
+	print -r -- "@ $SECONDS seconds"
+	print -r -- "$n (${#x[@]}):" "${x[@]}"
+	i=-1 z=${#x[@]}
+	while (( ++i < z )); do
+		v=${x[i]}
+		w=${#v}
+		if [[ $v = 0 ]]; then
+			x[i]=1
+		elif (( !(w & 1) )); then
+#			a=${v::w/2} b=${v:w/2}
+#			b=${b##+(0)}
+#			x[i]="$a ${b:-0}"
+			x[i]="${v::w/2} $((# ${v:w/2}))"
+		else
+			x[i]=$((# v * 2024 ))
+		fi
+	done
+	set -A x -- ${x[*]}
+done
+print -r -- "@ $SECONDS seconds"
+print -r -- "$n (${#x[@]}):" "${x[@]}"

2024/11/s1b

+#!/bin/mksh
+# because s1 is just too slow
+# needs LP64, which I fixed for s2
+
+set -o noglob
+set -A x -- $(<inputfile)
+IFS=,
+xs=${x[*]}
+IFS=$' \t\n'
+gcc -O3 -Wall -DINPUT=$xs s1b.c "$@" && time ./a.out

2024/11/s1b.c

+#include <err.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#ifndef NBLINK
+#define NBLINK 25
+#endif
+
+#define NX 1048576U
+
+static const unsigned long I[] = { INPUT };
+static unsigned long x[NX], y[NX];
+static char ss[24];
+static char *s;
+
+static size_t ltostr(unsigned long v);
+
+int
+main(void)
+{
+	size_t z, n, i, w;
+	int blink;
+
+	memcpy(x, I, sizeof(I));
+	z = sizeof(I) / sizeof(I[0]);
+	blink = -1;
+
+	while (++blink < NBLINK) {
+		printf("%d (%zu): …\n", blink, z);
+#if 0
+		i = -1;
+		while (++i < z)
+			printf("\t%lu\n", x[i]);
+#endif
+		n = 0;
+		i = -1;
+		while (++i < z) {
+			if (!x[i])
+				y[n++] = 1;
+			else if (!((w = ltostr(x[i])) & 1)) {
+				w >>= 1;
+				y[n++] = atol(s + w);
+				s[w] = '\0';
+				y[n++] = atol(s);
+			} else
+				y[n++] = x[i] * 2024UL;
+		}
+		memcpy(x, y, n * sizeof(I[0]));
+		z = n;
+	}
+	printf("%d (%zu): …\n", blink, z);
+#if 0
+	i = -1;
+	while (++i < z)
+		printf("\t%lu\n", x[i]);
+#endif
+	return (0);
+}
+
+static size_t
+ltostr(unsigned long v)
+{
+	s = ss + sizeof(ss);
+
+	*--s = '\0';
+	if (!v) {
+		*--s = '0';
+		return (1);
+	}
+	while (v) {
+		*--s = '0' + (v % 10U);
+		v /= 10U;
+	}
+	return (sizeof(ss) - 1U - (s - ss));
+}

2024/11/s2

+#!/bin/mksh
+
+set -o noglob
+set -A x -- $(<inputfile)
+IFS=,
+xs=${x[*]}
+IFS=$' \t\n'
+gcc -O3 -Wall -DINPUT=$xs s2.c "$@" && time ./a.out

2024/11/s2.c

+#include <err.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#ifndef NBLINK
+#define NBLINK 75
+#endif
+
+struct hte {
+	unsigned long long key;
+	unsigned long long value;
+};
+
+//#define HTSZ (1048576U * 256U)
+// thank you, https://www.reddit.com/r/adventofcode/comments/1hbnl0l/2024_day_11_plotted_the_number_of_distinct_stone/
+#define HTSZ 8192U
+#define HMAX (HTSZ / 8U * 7U)
+#define NENT ((unsigned long long)-1)
+struct hte ht[HTSZ];
+struct hte hn[HTSZ];
+size_t nkey;
+unsigned long long nval;
+
+static const unsigned int I[] = { INPUT };
+static char ss[24];
+static char *s;
+
+static size_t lltostr(unsigned long long v);
+
+#define BAFHror(eax,cl)	(((eax) >> (cl)) | ((eax) << (32 - (cl))))
+static inline unsigned int
+hash(unsigned int value)
+{
+	register unsigned int h = value, v;
+
+	v = (h >> 7) & 0x01010101U;
+	v += v << 1;
+	v += v << 3;
+	v ^= (h << 1) & 0xFEFEFEFEU;
+
+	v ^= BAFHror(v, 8);
+	v ^= (h = BAFHror(h, 8));
+	v ^= (h = BAFHror(h, 8));
+	h = v ^ BAFHror(h, 8);
+
+	return (h);
+}
+
+#define mbccS(x)		#x
+#define mbccS2(x)		mbccS(x)
+
+static inline void
+enter(unsigned long long key, unsigned long long howmany)
+{
+	unsigned int h = hash(key & 0xFFFFFFFFU) & (HTSZ - 1U);
+
+	nval += howmany;
+ search:
+	if (hn[h].key == key) {
+		hn[h].value += howmany;
+#if 0
+		printf("entering %llu + %llu = %llu\n", key, howmany, hn[h].value);
+#endif
+		return;
+	}
+	if (hn[h].key != NENT) {
+		/* lame, I know */
+		h = (h + 1U) & (HTSZ - 1U);
+		goto search;
+	}
+	if (++nkey == HMAX)
+		errx(1, "raise HTSZ");
+	hn[h].key = key;
+	hn[h].value = howmany;
+#if 0
+	printf("entering %llu = %llu\n", key, howmany);
+#endif
+}
+
+int
+main(void)
+{
+	size_t i, w;
+	unsigned long long v;
+	int blink;
+
+	memset(hn, '\xFF', sizeof(hn));
+	nkey = 0;
+	nval = 0;
+
+	i = sizeof(I) / sizeof(I[0]);
+	while (i--)
+		enter(I[i], 1U);
+	blink = -1;
+
+	while (++blink < NBLINK) {
+		printf("%d (%llu): %zu unique\n", blink, nval, nkey);
+		memcpy(ht, hn, sizeof(hn));
+		memset(hn, '\xFF', sizeof(hn));
+		nkey = 0;
+		nval = 0;
+
+		i = HTSZ;
+		while (i--) {
+			if (ht[i].key == NENT)
+				continue;
+			v = ht[i].key;
+#if 0
+			printf("from %llu\n", v);
+#endif
+			if (!v)
+				enter(1U, ht[i].value);
+			else if (!((w = lltostr(v)) & 1)) {
+				w >>= 1;
+				enter(atoll(s + w), ht[i].value);
+				s[w] = '\0';
+				enter(atoll(s), ht[i].value);
+			} else
+				enter(v * 2024ULL, ht[i].value);
+		}
+	}
+	printf("%d (%llu): %zu unique\n", blink, nval, nkey);
+	return (0);
+}
+
+static size_t
+lltostr(unsigned long long v)
+{
+	s = ss + sizeof(ss);
+
+	*--s = '\0';
+	if (!v) {
+		*--s = '0';
+		return (1);
+	}
+	while (v) {
+		*--s = '0' + (v % 10U);
+		v /= 10U;
+	}
+	return (sizeof(ss) - 1U - (s - ss));
+}