X-Git-Url: https://git.martlubbers.net/?a=blobdiff_plain;f=06b.c;h=bd2e22064bb9b72193123c1a02180af50947f8b3;hb=a622aa41088ddf29d38c50e2032ca84984b0e12b;hp=abc9892a1db3f480a98ce10fd08bb10f564bab3f;hpb=46b95a2f1d484eed878202f204561932dd9c548b;p=advent21.git

diff --git a/06b.c b/06b.c
index abc9892..bd2e220 100644
--- a/06b.c
+++ b/06b.c
@@ -2,33 +2,32 @@
 #include <stdlib.h>
 #include <string.h>
 
+#include <gmp.h>
+
 int main()
 {
-	char buf[1000];
-	if (fgets(buf, 1000, stdin) == NULL)
-		return 1;
-	long fish0[9] = {0};
-	long fish1[9] = {0};
-	long *this = &fish0[0];
-	long *that = &fish1[0];
+	char *buf = NULL;
+	size_t len = 0;
+	mpz_t fish[9];
+	for (int i = 0; i<9; i++)
+		mpz_init_set_ui(fish[i], 0);
 
+	getline(&buf, &len, stdin);
 	char *p = strtok(buf, ",");
-	this[atoi(p)]++;
-	while ((p = strtok(NULL, ",")) != NULL)
-		this[atoi(p)]++;
+	int n = atoi(p);
+	mpz_add_ui(fish[n], fish[n], 1);
+	while ((p = strtok(NULL, ",")) != NULL) {
+		n = atoi(p);
+		mpz_add_ui(fish[n], fish[n], 1);
+	}
 
 	for (long day = 0; day<256; day++) {
-		that[8] = this[0];
-		for (long i = 0; i<8; i++)
-			that[i] = this[i+1];
-		that[6] += this[0];
-		long *tmp = this;
-		this = that;
-		that = tmp;
+		n = (day+7) % 9;
+		mpz_add(fish[n], fish[n], fish[day%9]);
 	}
 
-	long sum = 0;
-	for (long i = 0; i<=8; i++)
-		sum += this[i];
-	printf("%lu\n", sum);
+	for (long i = 1; i<=8; i++)
+		mpz_add(fish[0], fish[0], fish[i]);
+	mpz_out_str(stdout, 10, fish[0]);
+	putchar('\n');
 }