Consider the problem of finding the least expensive routes to all cities in a network from a given starting point. For example, in the network shown on the mapbelow, the least expensive route from Pendleton to Peoria has cost 8 (going through Pierre and Pueblo).

When the algorithm has finished, shortestKnownDistance contains the shortest distance from the starting point to all reachable targets.

The following helper class expresses the distance to another city: public class Distance To implements Comparable { private String target; private int distance; public DistanceTo (String city, int dist) { target= city; distance = dist; } public String getTarget() { return target; } public int getDistance() { return distance; } public int compareTo (Distance To other) { return distance other.distance; } } All direct connections between cities are stored in a Map . The algorithm now proceeds as follows: Let from be the starting point. Add DistanceTo (from, o) to a priority queue. Construct a map shortest known Distance from city names to distances. While the priority queue is not empty Get its smallest element. If its target is not a key in shortest knownDistance Let d be the distance to that target. Put (target, d) into shortestknownDistance. For all cities c that have a direct connection from target Add DistanceTo(c, d + distance from target to c) to the priority queue.