some tweaks

lib/diamondtail/brain.ex

@@ -68,14 +68,17 @@ defmodule Diamondtail.Brain do
           else
             {id, s}
           end
-        end)
+        end) |> Map.new()
       end)
       |> resolve_state()
     end
 
-    def valid_actions(%GameState{type: :v, snakes: snakes, self: self}) do
+    def valid_actions(%GameState{type: :v, snakes: snakes, self: self} = state) do
       if Map.has_key?(snakes, self) do
-        [:up, :down, :left, :right]
+        [:up, :down, :left, :right] |> Enum.filter(fn action ->
+          result = apply_actions(state, action)
+          !snake_dies?(result, self)
+        end)
       else
         []
       end
@@ -102,7 +105,9 @@ defmodule Diamondtail.Brain do
 
         Enum.count(enemies) * genome.enemy_alive_weight +
         self.health * genome.own_health_weight +
+        self.length * genome.own_length_weight +
         Enum.sum_by(enemies, &(&1.health)) * genome.enemy_health_weight +
+        (Enum.sum_by(enemies, &(&1.length)) / (Enum.count(enemies) + 1)) * genome.enemy_length_weight +
         (Enum.map(enemies, &(abs(&1.head.x - self.head.x) + abs(&1.head.y - self.head.y))) |> Enum.min(&<=/2, fn -> 0 end)) * genome.enemy_head_distance_weight +
         (Enum.map(food, &(abs(&1.x - self.head.x) + abs(&1.y - self.head.y))) |> Enum.min(&<=/2, fn -> 0 end)) * genome.food_distance_weight
       else
@@ -124,10 +129,10 @@ defmodule Diamondtail.Brain do
 
       valid_actions = valid_actions(state)
       if valid_actions == [] do
-        if Map.has_key?(state.snakes, state.self) do
-          Float.max_finite()
-        else
-          Float.min_finite()
+        # Terminal state
+        case state.type do
+          :v -> Float.min_finite()
+          :q -> Float.max_finite()
         end
       else
         {score, _alpha, _beta} = valid_actions(state)
@@ -174,20 +179,26 @@ defmodule Diamondtail.Brain do
       end)
       # Eliminate snakes
       |> Map.update(:snakes, nil, fn snakes ->
-        Enum.filter(snakes, fn {snake_id, snake} ->
-          # Die if health is less than or equal to 0
-          snake.health > 0 &&
-          # Die if head is out of bounds
-          snake.head.x >= 0 && snake.head.x < state.width &&
-          snake.head.y >= 0 && snake.head.y < state.height &&
-          # Die if head is in a tail
-          !Enum.any?(state.snakes, fn {_, %{body: body}} -> Enum.member?(body, snake.head) end) &&
-          # Die if head is on head of a DIFFERENT snake of equal or greater length
-          !Enum.any?(state.snakes, fn {id, %{head: h, length: l}} -> snake.head == h && snake.length <= l && id != snake_id end)
+        Enum.filter(snakes, fn {snake_id, _snake} ->
+          !snake_dies?(state, snake_id)
         end) |> Map.new()
       end)
     end
 
+    defp snake_dies?(state, snake_id) do
+      snake = state.snakes[snake_id]
+
+      # Die if health is less than or equal to 0
+      snake.health <= 0 ||
+      # Die if head is out of bounds
+      snake.head.x < 0 || snake.head.x >= state.width ||
+      snake.head.y < 0 || snake.head.y >= state.height ||
+      # Die if head is in a tail
+      Enum.any?(state.snakes, fn {_, %{body: body}} -> Enum.member?(body, snake.head) end) ||
+      # Die if head is on head of a DIFFERENT snake of equal or greater length
+      Enum.any?(state.snakes, fn {id, %{head: h, length: l}} -> snake.head == h && snake.length <= l && id != snake_id end)
+    end
+
     defp apply_action_to_snake(snake, move) do
       delta = case move do
         :up -> %{x: 0, y: 1}
@@ -211,6 +222,12 @@ defmodule Diamondtail.Brain do
         {action, GameState.evaluate_state(genome, qstate, ceil(genome.search_depth))}
       end, ordered: false)
 
+    if Enum.empty?(options) do
+      %{
+        move: :left,
+        shout: "I'm dead, good game!"
+      }
+    else
       {:ok, {action, score}} = Enum.max_by(options, fn {:ok, {_, s}} -> s end)
 
       %{
@@ -219,3 +236,4 @@ defmodule Diamondtail.Brain do
       }
     end
   end
+end

lib/diamondtail/population.ex

@@ -16,7 +16,9 @@ defmodule Diamondtail.Population do
 
       field :enemy_alive_weight, float()
       field :own_health_weight, float()
+      field :own_length_weight, float()
       field :enemy_health_weight, float()
+      field :enemy_length_weight, float()
       field :enemy_head_distance_weight, float()
       field :food_distance_weight, float()
 
@@ -57,10 +59,12 @@ defmodule Diamondtail.Population do
     def random() do
       %Genome{
         mutation_chance: random_between(0.1, 0.2),
-        mutation_max_amplitude: random_between(0.1, 0.05),
+        mutation_max_amplitude: random_between(0.2, 0.05),
         enemy_alive_weight: random_between(-100.0, -200.0),
         own_health_weight: random_between(0.7, 1.0),
-        enemy_health_weight: random_between(-0.8, -0.4),
+        own_length_weight: random_between(5, 10),
+        enemy_health_weight: random_between(-0.8, -0.4), # Summed
+        enemy_length_weight: random_between(-10, -5), # Averaged
 
         # both of the following are compared to the nearest object, to avoid overrewarding when there are more enemies/foods
         enemy_head_distance_weight: random_between(1, 2), # maximize distance, reward staying away

lib/diamondtail/router.ex

@@ -18,7 +18,7 @@ defmodule Diamondtail.Router do
     |> send_resp(200, JSON.encode!(%{
       apiversion: "1",
       author: "kodicraft",
-      color: "#8cd9ff",
+      color: "#4684ff",
       head: "trans-rights-scarf",
       tail: "hook",
       version: Mix.Project.config()[:version]