[2020][ruby][24.x] use axial coordinates

2020/ruby/day_24.rb

@@ -7,17 +7,17 @@ def parse(line)
   ss = StringScanner.new(line)
   until ss.eos?
     deltas << case
-              when ss.scan(/e/)  then [ 1, -1,  0]
+              when ss.scan(/e/)  then [ 1,  0]
-              when ss.scan(/se/) then [ 0, -1,  1]
+              when ss.scan(/se/) then [ 0,  1]
-              when ss.scan(/sw/) then [-1,  0,  1]
+              when ss.scan(/sw/) then [-1,  1]
-              when ss.scan(/w/)  then [-1,  1,  0]
+              when ss.scan(/w/)  then [-1,  0]
-              when ss.scan(/nw/) then [ 0,  1, -1]
+              when ss.scan(/nw/) then [ 0, -1]
-              when ss.scan(/ne/) then [ 1,  0, -1]
+              when ss.scan(/ne/) then [ 1, -1]
               else fail
               end
   end
 
-  deltas.inject {|(x,y,z),(dx,dy,dz)| [x+dx, y+dy, z+dz] }
+  deltas.inject {|c,d| c.zip(d).map {|c,d| c+d }}
 end
 
 NEIGHBORS = %w[ e se sw w nw ne ].map {|dir| parse(dir) }
@@ -25,11 +25,11 @@ def tick(tiles)
   coords = Set.new(tiles.flat_map {|coord|
     [
       coord,
-      *NEIGHBORS.map {|n| coord.zip(n).map {|c,d| c + d }},
+      *NEIGHBORS.map {|n| coord.zip(n).map {|c,d| c+d }},
     ]
   })
   Set.new(coords.select {|coord|
-    live_neighbors = NEIGHBORS.map {|n| coord.zip(n).map {|c,d| c + d }}.count {|c| tiles.include?(c) }
+    live_neighbors = NEIGHBORS.map {|n| coord.zip(n).map {|c,d| c+d }}.count {|c| tiles.include?(c) }
     if tiles.include?(coord)
       (1..2).cover?(live_neighbors)
     else