Vehicle routing problem (VRP) is found to be widely applicable
to logistics distribution, school bus routing and mail etc. It has
been studied for the last 40 years. A typical VRP can be described
as a weighted graph. Fig. 1 shows an example of VRP, where the depot
is denoted as 0 and the customers are denoted as 1 through 10.
The solution includes three routes: 0–2–1–5–7–0, 0–3–4–6–0 and
0–8–9–10–0.