diff --git a/day07.py b/day07.py
index 009f342..3de8b51 100644
--- a/day07.py
+++ b/day07.py
@@ -32,16 +32,15 @@ def getBagContent(bag_line):
 
 def getPossibleBagsForMyColor(color_dict, my_color):
     if my_color not in color_dict:
-        return []
+        return set()
 
-    color_list = color_dict[my_color]
+    color_set = set(color_dict[my_color])
     for color in color_dict[my_color]:
-        extend_list = getPossibleBagsForMyColor(color_dict, color)
-        for extra_color in extend_list:
-            if extra_color not in color_list:
-                color_list.append(extra_color)
+        extend_set = getPossibleBagsForMyColor(color_dict, color)
+        for extra_color in extend_set:
+            color_set.add(extra_color)
 
-    return color_list
+    return color_set
 
 
 def getBagContentCount(color_dict, my_color):