diff --git a/extra/bringing-a-gun-to-a-trainer-fight/solution.py b/extra/bringing-a-gun-to-a-trainer-fight/solution.py
index c745adf..bc4d031 100644
--- a/extra/bringing-a-gun-to-a-trainer-fight/solution.py
+++ b/extra/bringing-a-gun-to-a-trainer-fight/solution.py
@@ -13,19 +13,13 @@ def solution(dimentions, your_position, trainer_position, distance):
     return sum(1 for (position, is_trainer) in nearest_target.values() if is_trainer and line_length(your_position, position) <= distance)
 
 def generate_room_id(dimentions, your_position, distance):
-    memo = []
     room_width = dimentions[0]
     room_height = dimentions[1]
     x_range = distance / room_width + 1
     y_range = distance / room_height + 1
-    for room_x in range(x_range):
-        for room_y in range(y_range):
-            memo += [(room_x, room_y)]
+    for room_x in range(-x_range, x_range):
+        for room_y in range(-y_range, y_range):
             yield room_x, room_y
-    for room_x, room_y in memo:
-        yield - room_x - 1, room_y
-        yield room_x, - room_y - 1
-        yield - room_x - 1, - room_y - 1
 
 def generate_positions(dimentions, your_position, trainer_position, distance):
     room_width, room_height = dimentions