advent2025

commit afb256e15a18d1ae501cfb9162adfdea1b8c584e
parent b882276f2387d250e46e6d88919c513aaf3bcbf3
Author: bsandro <email@bsandro.tech>
Date:   Thu,  4 Dec 2025 20:14:06 +0200

day04 optimization that actually made thing slower (but added more sanity as far as cellular automata goes

Diffstat:
M
day04.c
 | 
11
+++++------

1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/day04.c b/day04.c
@@ -1,4 +1,5 @@
 #include <stdio.h>
+#include <string.h>
 #include "cputime.h"
 
 // +1 on all sides
@@ -26,10 +27,12 @@ int count_adj(Map map, int x, int y) {
 }
 
 int clean(Map map) {
+    Map map1;
+    memcpy(map1, map, sizeof(Map));
     int rem = 0;
     for (int y=1;y<H-1;++y) {
         for (int x=1;x<W-1;++x) {
-            if (map[y][x]=='@'&&count_adj(map, x, y)<4) {
+            if (map1[y][x]=='@'&&count_adj(map1, x, y)<4) {
                 map[y][x]='.';
                 rem++;
             }
@@ -52,15 +55,11 @@ int main(void) {
     }
 
     int p1 = 0;
-    for (int y=1;y<H-1;++y) {
-        for (int x=1;x<W-1;++x) {
-            if (map[y][x]=='@'&&count_adj(map, x, y)<4) p1++;
-        }
-    }
     int p2 = 0;
     while (1) {
         int rem = clean(map);
         p2 += rem;
+        if (p1==0) p1 = rem;
         if (rem==0) break;
     }
     printf("p1: %d\np2: %d\n", p1, p2);