[Refactor] Optimized topological sort stack to append right and reverse instead of appendleft.

Author: exterkamp

structures/graph.py

@@ -104,13 +104,13 @@ def dfs(vertex):
                 if i not in visited:
                     dfs(i)
 
-            stack.insert(0, vertex)
+            stack.append(vertex)
 
         for i in range(self.verticies):
             if i not in visited:
                 dfs(i)
 
-        return stack
+        return stack[::-1]
 
 class WeightedGraphNode():