From e57f82e16ce6fb903c6568dbc67a78937c0c8fa4 Mon Sep 17 00:00:00 2001
From: Ian C <ianc@noddybox.co.uk>
Date: Thu, 9 Dec 2021 20:31:05 +0000
Subject: Changed day 6 to a method hinted at on-line.

---
 6.c  | 39 ++++++++++++++++-----------------------
 6a.c | 40 ++++++++++++++--------------------------
 2 files changed, 30 insertions(+), 49 deletions(-)

diff --git a/6.c b/6.c
index 8476b74..b0c1048 100644
--- a/6.c
+++ b/6.c
@@ -2,8 +2,6 @@
 #include <stdio.h>
 #include <string.h>
 
-#define MAX_BOARDS 100
-
 static char *ReadLine(char *p, size_t size, FILE *fp)
 {
     if ((p=fgets(p, size, fp)))
@@ -22,8 +20,8 @@ static char *ReadLine(char *p, size_t size, FILE *fp)
 int main(void)
 {
     char buff[1024];
-    int *num = NULL;
-    int num_count = 0;
+    unsigned long long num[9] = {0};
+    unsigned long long num_count = 0;
     char *p = NULL;
     int f = 0;
     int cycle = 0;
@@ -34,36 +32,31 @@ int main(void)
 
     while(p)
     {
-        num = realloc(num, (num_count + 1) * sizeof *num);
-        num[num_count++] = atoi(p);
+        num[atoi(p)]++;
         p = strtok(NULL, ",");
     }
 
     for(cycle = 0; cycle < 80; cycle++)
     {
-        int to_add = 0;
+        unsigned long long zero = 0;
 
-        for(f = 0; f < num_count; f++)
-        {
-            if (num[f] == 0)
-            {
-                to_add++;
-                num[f] = 6;
-            }
-            else
-            {
-                num[f]--;
-            }
-        }
+        zero = num[0];
 
-        for(f = 0; f < to_add; f++)
+        for(f=0; f < 8; f++)
         {
-            num = realloc(num, (num_count + 1) * sizeof *num);
-            num[num_count++] = 8;
+            num[f] = num[f+1];
         }
+
+        num[6] += zero;
+        num[8] = zero;
+    }
+
+    for(f = 0; f < 9; f++)
+    {
+        num_count += num[f];
     }
 
-    printf("num_count=%d\n", num_count);
+    printf("num_count=%llu\n", num_count);
 
     return 0;
 }
diff --git a/6a.c b/6a.c
index da667f2..8949db5 100644
--- a/6a.c
+++ b/6a.c
@@ -2,8 +2,6 @@
 #include <stdio.h>
 #include <string.h>
 
-#define MAX_BOARDS 100
-
 static char *ReadLine(char *p, size_t size, FILE *fp)
 {
     if ((p=fgets(p, size, fp)))
@@ -22,10 +20,10 @@ static char *ReadLine(char *p, size_t size, FILE *fp)
 int main(void)
 {
     char buff[1024];
-    char *num = NULL;
+    unsigned long long num[9] = {0};
     unsigned long long num_count = 0;
     char *p = NULL;
-    unsigned long long f = 0;
+    int f = 0;
     int cycle = 0;
 
     ReadLine(buff, sizeof buff, stdin);
@@ -34,38 +32,28 @@ int main(void)
 
     while(p)
     {
-        num = realloc(num, (num_count + 1) * sizeof *num);
-        num[num_count++] = atoi(p);
+        num[atoi(p)]++;
         p = strtok(NULL, ",");
     }
 
     for(cycle = 0; cycle < 256; cycle++)
     {
-        int to_add = 0;
+        unsigned long long zero = 0;
 
-        for(f = 0; f < num_count; f++)
-        {
-            if (num[f] == 0)
-            {
-                to_add++;
-                num[f] = 6;
-            }
-            else
-            {
-                num[f]--;
-            }
-        }
+        zero = num[0];
 
-        if (to_add)
+        for(f=0; f < 8; f++)
         {
-            num = realloc(num, (num_count + to_add) * sizeof *num);
-            for(f = 0; f < to_add; f++)
-            {
-                num[num_count++] = 8;
-            }
+            num[f] = num[f+1];
         }
 
-        printf("cycle/num_count = %d/%llu\n", cycle, num_count);
+        num[6] += zero;
+        num[8] = zero;
+    }
+
+    for(f = 0; f < 9; f++)
+    {
+        num_count += num[f];
     }
 
     printf("num_count=%llu\n", num_count);
-- 
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