diff --git a/2023/ruby/day_02.rb b/2023/ruby/day_02.rb
index f93657e..815bc52 100644
--- a/2023/ruby/day_02.rb
+++ b/2023/ruby/day_02.rb
@@ -1,13 +1,13 @@
 input = ARGF.read
 
-def cubes(input)
+def parse_cubes(input)
   input
     .scan(/(\d+) (\w+)/)
     .to_h(&:reverse)
     .transform_values(&:to_i)
 end
 
-bag = cubes("12 red cubes, 13 green cubes, and 14 blue cubes")
+bag = parse_cubes("12 red cubes, 13 green cubes, and 14 blue cubes")
 
 Game = Data.define(:id, :reveals) do
   def possible?(bag)
@@ -22,7 +22,7 @@ games = input
   .map {|id, reveals|
     Game.new(
       id.to_i,
-      reveals.split(?;).map { cubes(_1) }
+      reveals.split(?;).map { parse_cubes(_1) }
     )
   }
 
diff --git a/2023/ruby/day_03.rb b/2023/ruby/day_03.rb
new file mode 100644
index 0000000..7812d42
--- /dev/null
+++ b/2023/ruby/day_03.rb
@@ -0,0 +1,43 @@
+cur_num = nil
+nums = {}
+syms = {}
+ARGF.readlines(chomp: true).each.with_index do |row, y|
+  row.chars.each.with_index do |c, x|
+    case c
+    when /\d/
+      if cur_num
+        cur_num << c
+      else
+        cur_num = c
+      end
+    else
+      if cur_num
+        nums[[y,x-cur_num.length]] = cur_num.to_i
+        cur_num = nil
+      end
+
+      if c != ?.
+        syms[[y,x]] = c
+      end
+    end
+  end
+
+  if cur_num
+    nums[[y, row.length-cur_num.length]] = cur_num.to_i
+    cur_num = nil
+  end
+end
+
+p nums
+  .filter_map {|(y,x), num|
+    dy = (-1..1).to_a
+    dx = (-1..num.digits.length).to_a
+    if dy.product(dx)
+        .map {|dy,dx| [y+dy,x+dx] }
+        .any? { syms.has_key?(_1) }
+      num
+    else
+      nil
+    end
+  }
+  .sum