Update app.py

app.py

@@ -113,8 +113,8 @@ for task_id, ga in enumerate(gas):
         
 
 # Trade populations between tasks
-for i in range(num_tasks):
-    for j in range(i+1, num_tasks):
+for i in range(len(gas)):
+    for j in range(i+1, len(gas)):
         ga1 = gas[i]
         ga2 = gas[j]
         population1 = ga1.population