day 4 optimize

day04/sol.ivy

@@ -4,7 +4,9 @@ op ch pad g =
     (g, (((rho g)[2]) rho ch)) ,% ((1 + (rho g)[1]) rho ch)
 
 op adj g =
-    (1 rot g) + (-1 rot g) + (1 flip g) + (-1 flip g) + (1 rot 1 flip g) + (-1 rot 1 flip g) + (1 rot -1 flip g) + (-1 rot -1 flip g)
+    h = g + (1 rot g) + (-1 rot g)
+    v = h + (1 flip h) + (-1 flip h)
+    v - g
 
 op solve g =
     gx = 0 pad (g=="@")
@@ -21,12 +23,6 @@ op solve2 g =
     rx = remove gx
     +/,(gx - rx)
 
-x = "@" == "." pad sample
-x
-adj x
-""
-x and 4 > adj x
-
 solve sample
 solve2 sample