Databases Reference
In-Depth Information
Figure 7-6. Reaching Melbourne, the third-closest city to the start node of Sydney
In
Figure 7-7
, the next layer of neighboring nodes from our solved ones are Adelaide at
18 hours from Sydney (via Canberra and Melbourne); Cairns, at 31 hours from Sydney
(via Brisbane); and Alice Springs, at 19 hours from Sydney via Canberra, or 40 hours
via Brisbane. We choose Adelaide and consider it solved at a cost of 18 hours.
We don't consider the path Melbourne→Sydney because its destination
is a solved node—in fact, in this case, it's the start node, Sydney.
The next layer of neighboring nodes from our solved ones are Perth—our final desti‐
nation—which is 50 hours from Sydney via Adelaide; Alice Springs, which is 19 hours
from Sydney via Canberra or 33 hours via Adelaide; and Cairns, which is 31 hours from
Sydney via Brisbane.
We choose Alice Springs in this case because it has the current shortest path, even though
with a god's eye view we know that actually it'll be shorter in the end to go from Adelaide
to Perth—just ask any passing bushman. Our cost is 19 hours, as shown in
Figure 7-8
.
