The answer is "shortest route solution technique".
When we apply this technique or method, it is useful and easy to characterize the system of truck routes as a network.
We originate the shortest route solution technique by starting at node 1 which is the origin and finding the shortest time which is essential to get to a directly connected node. Now you will notice that the three nodes are directly connected to node 1 are 2, 3, and 4, (check the attachment).
Of these three nodes, the shortest time is 9 hours to node 3. Therefore, we have found our first shortest route from nodes 1 to 3. We will now raise to nodes 1 and 3 as the permanent set to show that we have found the shortest route to these nodes.