private static Map<Integer, List<Edge>> buildGraph(List<Edge> edges) {
Map<Integer, List<Edge>> graph = new TreeMap<>();
for (Edge edge : edges) {
if (!graph.containsKey(edge.getStartNode())) {
graph.put((Integer) edge.getStartNode(), new ArrayList<Edge>());
}
graph.get(edge.getStartNode()).add(edge);
if (!graph.containsKey(edge.getEndNode())) {
graph.put((Integer) edge.getEndNode(), new ArrayList<Edge>());
}
Edge reversedEdge = new Edge(edge.getEndNode(), edge.getStartNode(), edge.getWightl());
graph.get(edge.getEndNode()).add(reversedEdge);
}
return graph;
}
public Set<NodeEdgePair> getAdjecents() {
// Set<Edge> edges = getEdges();
Set<NodeEdgePair> nodes = new HashSet<>();
for (Edge e : edges) {
Node start = e.getStartNode();
Node end = e.getEndNode();
Node other = start == this ? end : start;
nodes.add(new NodeEdgePair(e, other));
}
return nodes;
}
// Dosn't work like dijkstra. Work like kruskal
private static void dijkstra(List<Edge> edges, int startingNode) {
Map<Integer, List<Edge>> graph = buildGraph(edges);
// use reverse order priority queue
PriorityQueue<Edge> priorityQueue = new PriorityQueue<Edge>();
boolean[] visitedNode = new boolean[graph.size()];
int[] parent = new int[graph.size()];
int[] distance = new int[graph.size()];
// initialize the parent and distance array
for (int i = 0; i < distance.length; i++) {
distance[i] = Integer.MAX_VALUE;
parent[i] = -1;
}
visitedNode[startingNode] = true;
parent[startingNode] = startingNode;
distance[startingNode] = 0;
do {
// TODO
List<Edge> childOfStartingtNode = graph.get(startingNode);
for (Edge edge : childOfStartingtNode) {
if (!edge.isConnected()) {
priorityQueue.add(edge);
}
}
Edge currentEdge = priorityQueue.poll();
currentEdge.setConnected(true);
if (!visitedNode[currentEdge.getEndNode()]) {
visitedNode[currentEdge.getEndNode()] = true;
parent[currentEdge.getEndNode()] = currentEdge.getStartNode();
int newDistance = distance[currentEdge.getStartNode()] + currentEdge.getWightl();
if (distance[currentEdge.getEndNode()] > newDistance) {
distance[currentEdge.getEndNode()] = newDistance;
}
startingNode = currentEdge.getEndNode();
}
} while (priorityQueue.size() > 0);
for (int i = 0; i < graph.size(); i++) {
System.out.println("Node: " + i);
System.out.println("distance: " + distance[i]);
System.out.println("Parent: " + parent[i]);
System.out.println();
}
}
