Add drawing code and elementwise reduction.

src/advent/util.cr

@@ -7,6 +7,12 @@ class Array(T)
     dest
   end
 
+  def reduce_elementwise(&block)
+    reduce do |l, r|
+       l.zip_with(r) { |a, b| yield a, b }
+    end
+  end
+
   def union
     reduce(T.new) do |l, r|
       l | r
@@ -18,6 +24,15 @@ class Array(T)
       l & r
     end
   end
+
+  def draw(width, maps)
+    self.each_slice(width) do |slice|
+      slice.each do |c|
+        print maps[c]
+      end
+      puts
+    end
+  end
 end
 
 struct Tuple(*T)