Day 11: remove debug code, simpler datastructure

day11/day11part1.exs

@@ -5,52 +5,47 @@ defmodule Day11Part1 do
     |> Enum.map(&String.to_charlist/1)
     |> parse_seat_plan()
     |> run_until_stable()
-    |> elem(2)
     |> count_occupied()
     |> IO.inspect()
   end
 
-  def run_until_stable(state) do
+  def run_until_stable(seats) do
-    new_state = tick(state)
+    new_seats = tick(seats)
 
-    if new_state == state do
+    if new_seats == seats do
-      state
+      seats
     else
-      run_until_stable(new_state)
+      run_until_stable(new_seats)
     end
   end
 
-  def tick({width, height, old_seats}) do
+  def tick(seats) do
-    new_seats =
+    Map.new(seats, fn {{x, y}, old_seat} -> toggle(old_seat, x, y, seats) end)
-      for(
-        x <- 0..(width - 1),
-        y <- 0..(height - 1),
-        do: {x, y}
-      )
-      |> Enum.reduce(%{}, fn {x, y}, new_seats ->
-        toggle(old_seats[{x, y}], x, y, old_seats, new_seats)
-      end)
-
-    {width, height, new_seats}
   end
 
-  def toggle(:empty, x, y, old_seats, new_seats) do
+  def toggle(:empty, x, y, seats) do
-    if occupied_adjacent(x, y, old_seats) == 0 do
+    new_value =
-      Map.put(new_seats, {x, y}, :occupied)
+      if occupied_adjacent(x, y, seats) == 0 do
+        :occupied
       else
-      Map.put(new_seats, {x, y}, :empty)
+        :empty
-    end
       end
 
-  def toggle(:occupied, x, y, old_seats, new_seats) do
+    {{x, y}, new_value}
-    if occupied_adjacent(x, y, old_seats) >= 4 do
+  end
-      Map.put(new_seats, {x, y}, :empty)
+
+  def toggle(:occupied, x, y, seats) do
+    new_value =
+      if occupied_adjacent(x, y, seats) >= 4 do
+        :empty
       else
-      Map.put(new_seats, {x, y}, :occupied)
+        :occupied
-    end
       end
 
-  def toggle(:floor, x, y, _, new_seats), do: Map.put(new_seats, {x, y}, :floor)
+    {{x, y}, new_value}
+  end
+
+  def toggle(:floor, x, y, _), do: {{x, y}, :floor}
 
   def occupied_adjacent(x, y, seats) do
     adjacent = [
@@ -74,37 +69,24 @@ defmodule Day11Part1 do
   end
 
   def parse_seat_plan(input) do
-    Enum.reduce(input, {0, 0, %{}}, fn row, {_x, y, seats} ->
+    {_, seats} =
-      {x, seats} =
+      Enum.reduce(input, {0, %{}}, fn row, {y, seats} ->
+        {_, seats} =
           Enum.reduce(row, {0, seats}, fn seat, {x, seats} ->
             seat =
               case seat do
                 ?L -> :empty
                 ?. -> :floor
+                ?# -> :occupied
               end
 
             {x + 1, Map.put(seats, {x, y}, seat)}
           end)
 
-      {x, y + 1, seats}
+        {y + 1, seats}
       end)
-  end
 
-  def visualize({width, height, seats}) do
+    seats
-    for y <- 0..(height - 1) do
-      for x <- 0..(width - 1) do
-        char =
-          case seats[{x, y}] do
-            :empty -> "L"
-            :floor -> "."
-            :occupied -> "#"
-          end
-
-        IO.write(char)
-      end
-
-      IO.write("\n")
-    end
   end
 end
 

day11/day11part2.exs

@@ -5,52 +5,47 @@ defmodule Day11Part2 do
     |> Enum.map(&String.to_charlist/1)
     |> parse_seat_plan()
     |> run_until_stable()
-    |> elem(2)
     |> count_occupied()
     |> IO.inspect()
   end
 
-  def run_until_stable(state) do
+  def run_until_stable(seats) do
-    new_state = tick(state)
+    new_seats = tick(seats)
 
-    if new_state == state do
+    if new_seats == seats do
-      state
+      seats
     else
-      run_until_stable(new_state)
+      run_until_stable(new_seats)
     end
   end
 
-  def tick({width, height, old_seats}) do
+  def tick(seats) do
-    new_seats =
+    Map.new(seats, fn {{x, y}, old_seat} -> toggle(old_seat, x, y, seats) end)
-      for(
-        x <- 0..(width - 1),
-        y <- 0..(height - 1),
-        do: {x, y}
-      )
-      |> Enum.reduce(%{}, fn {x, y}, new_seats ->
-        toggle(old_seats[{x, y}], x, y, old_seats, new_seats)
-      end)
-
-    {width, height, new_seats}
   end
 
-  def toggle(:empty, x, y, old_seats, new_seats) do
+  def toggle(:empty, x, y, seats) do
-    if occupied_visible(x, y, old_seats) == 0 do
+    new_value =
-      Map.put(new_seats, {x, y}, :occupied)
+      if occupied_visible(x, y, seats) == 0 do
+        :occupied
       else
-      Map.put(new_seats, {x, y}, :empty)
+        :empty
-    end
       end
 
-  def toggle(:occupied, x, y, old_seats, new_seats) do
+    {{x, y}, new_value}
-    if occupied_visible(x, y, old_seats) >= 5 do
+  end
-      Map.put(new_seats, {x, y}, :empty)
+
+  def toggle(:occupied, x, y, seats) do
+    new_value =
+      if occupied_visible(x, y, seats) >= 5 do
+        :empty
       else
-      Map.put(new_seats, {x, y}, :occupied)
+        :occupied
-    end
       end
 
-  def toggle(:floor, x, y, _, new_seats), do: Map.put(new_seats, {x, y}, :floor)
+    {{x, y}, new_value}
+  end
+
+  def toggle(:floor, x, y, _), do: {{x, y}, :floor}
 
   def occupied_visible(x, y, seats) do
     directions = [
@@ -83,8 +78,9 @@ defmodule Day11Part2 do
   end
 
   def parse_seat_plan(input) do
-    Enum.reduce(input, {0, 0, %{}}, fn row, {_x, y, seats} ->
+    {_, seats} =
-      {x, seats} =
+      Enum.reduce(input, {0, %{}}, fn row, {y, seats} ->
+        {_, seats} =
           Enum.reduce(row, {0, seats}, fn seat, {x, seats} ->
             seat =
               case seat do
@@ -96,25 +92,10 @@ defmodule Day11Part2 do
             {x + 1, Map.put(seats, {x, y}, seat)}
           end)
 
-      {x, y + 1, seats}
+        {y + 1, seats}
       end)
-  end
 
-  def visualize({width, height, seats}) do
+    seats
-    for y <- 0..(height - 1) do
-      for x <- 0..(width - 1) do
-        char =
-          case seats[{x, y}] do
-            :empty -> "L"
-            :floor -> "."
-            :occupied -> "#"
-          end
-
-        IO.write(char)
-      end
-
-      IO.write("\n")
-    end
   end
 end