public static void dijkstra(
ListenableUndirectedWeightedGraph<String, DefaultWeightedEdge> g,
String initNode,
String endNode) {
// Variable creation/assignment
resultNum++;
int loopCnt = 0; // Keep count of loops
String currNode = initNode; // always starts as initial node
Set<String> allVerts = new LinkedHashSet<String>();
allVerts = g.vertexSet(); // All vertices in the graph
Set<DefaultWeightedEdge> allEdges = new LinkedHashSet<DefaultWeightedEdge>();
allEdges = g.edgeSet(); // All edges in the graph
Set<String> visited = new LinkedHashSet<String>(); // List of visited vertices
Set<String> unvisited = new LinkedHashSet<String>(); // List of unvisited vertices
for (String v : allVerts)
// adding the rest of the nodes to unvisited set
{
if (v != initNode) {
unvisited.add(v);
}
}
Map<String, Double> vertVals = new HashMap<String, Double>();
for (String v : allVerts)
// setting a value of INFINITY to all vertices.
{
vertVals.put(v, Double.POSITIVE_INFINITY);
}
vertVals.put(initNode, 0.0); // Setting the initial node value to 0
visited.add(initNode); // adding initial node to visited set
List<String> path = new ArrayList<String>();
path.add(initNode); // adding initial node to path
// END Variable creation/assignment
System.out.println("Result " + resultNum + ":");
while (!visited.contains(endNode) && loopCnt < 1000000) {
loopCnt++;
for (DefaultWeightedEdge e : allEdges)
// Set weight values for neighbors of current node
{
if (g.getEdgeSource(e) == currNode
&& g.getEdgeWeight(e) < (vertVals.get(g.getEdgeTarget(e)) + vertVals.get(currNode))
&& !visited.contains(g.getEdgeTarget(e)))
// if the edge comes from the currentNode AND the value of that edges target is greater than
// the distance to the current node AND the target hasn't been visited
{
vertVals.put(
g.getEdgeTarget(e),
g.getEdgeWeight(e) + vertVals.get(currNode)); // Update value of that vertex
} else if (g.getEdgeTarget(e) == currNode
&& g.getEdgeWeight(e) < (vertVals.get(g.getEdgeSource(e)) + vertVals.get(currNode))
&& !visited.contains(g.getEdgeSource(e)))
// if the edge comes to the currentNode AND the value of that edges source is greater than
// the distance from the starting node to the current node AND the source hasn't been
// visited
{
vertVals.put(
g.getEdgeSource(e),
g.getEdgeWeight(e) + vertVals.get(currNode)); // Update value of that vertex
}
}
Double lowest =
Double.POSITIVE_INFINITY; // used to find lowest of the current neighbor vertices
String n = ""; // temporary string for storing vertex names
for (DefaultWeightedEdge e : allEdges)
// finding the lowest of the current neighbor vertices to set to currentNode
{
if (g.getEdgeSource(e) == currNode
&& g.getEdgeWeight(e) < lowest
&& !visited.contains(g.getEdgeTarget(e)))
// if the edge comes from the currentNode AND it's the smallest vertex value that has not
// been visited and .
{
lowest = g.getEdgeWeight(e);
n = g.getEdgeTarget(e);
} else if (g.getEdgeTarget(e) == currNode
&& g.getEdgeWeight(e) < lowest
&& !visited.contains(g.getEdgeSource(e))) {
lowest = g.getEdgeWeight(e);
n = g.getEdgeSource(e);
}
}
if (n != "") {
currNode = n;
visited.add(currNode);
path.add(currNode);
} else {
currNode = path.get(path.size() - 2);
visited.add(currNode);
}
}
System.out.println("Shortest Path: " + path);
System.out.println("Cost: " + vertVals.get(endNode));
System.out.println();
}
public static void main(String[] args) {
// Adding Vertices
// test1
test1.addVertex("a");
test1.addVertex("b");
test1.addVertex("c");
test1.addVertex("d");
// test2
test2.addVertex("a");
test2.addVertex("b");
test2.addVertex("c");
test2.addVertex("d");
test2.addVertex("e");
// Adding Edges:
// test1
test1.addEdge("a", "b");
test1.addEdge("b", "c");
test1.addEdge("c", "d");
test1.addEdge("d", "a");
test1.addEdge("d", "b");
// test2
test2.addEdge("a", "b");
test2.addEdge("a", "d");
test2.addEdge("b", "c");
test2.addEdge("b", "e");
test2.addEdge("c", "e");
test2.addEdge("d", "e");
// Setting Edge Weights:
// test1
test1.setEdgeWeight(test1.getEdge("a", "b"), 1.0);
test1.setEdgeWeight(test1.getEdge("b", "c"), 1.0);
test1.setEdgeWeight(test1.getEdge("c", "d"), 2.0);
test1.setEdgeWeight(test1.getEdge("d", "a"), 3.0);
test1.setEdgeWeight(test1.getEdge("d", "b"), 2.0);
// test2
test2.setEdgeWeight(test2.getEdge("a", "b"), 9.0);
test2.setEdgeWeight(test2.getEdge("a", "d"), 1.0);
test2.setEdgeWeight(test2.getEdge("b", "c"), 1.0);
test2.setEdgeWeight(test2.getEdge("b", "e"), 2.0);
test2.setEdgeWeight(test2.getEdge("c", "e"), 6.0);
test2.setEdgeWeight(test2.getEdge("d", "e"), 2.0);
dijkstra(test1, "a", "c");
dijkstra(test2, "a", "c");
}
