Update python code with TODO

shortest_path.py

@@ -99,7 +99,7 @@ if __name__ == "__main__":
         for i in range(nb_nodes):
             dist, path = bellman_ford(table, i)
             if dist == -1:
-                continue
+                continue  # TODO: if there is no shortest path (negative cycle or empty path), put a 0 value instead of not showing it at all
 
             if output_fd == sys.stdout or output_fd == sys.stderr:
                 print("source : "+str(i))