Created
April 20, 2016 14:59
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| package graphs; | |
| import java.util.Comparator; | |
| import java.util.PriorityQueue; | |
| public class SpanningTree { | |
| private Double[] distances; | |
| private WeightedGraph graph; | |
| boolean debug = true; | |
| public class VertexEdgeComparator implements Comparator<Integer> { | |
| @Override | |
| public int compare(Integer o1, Integer o2) { | |
| double minFirst = getMin(o1); | |
| double minSecond = getMin(o2); | |
| if (minFirst > minSecond) { | |
| return 1; | |
| } else if (minFirst == minSecond) { | |
| return 0; | |
| } else { | |
| return -1; | |
| } | |
| } | |
| private double getMin(Integer o1) { | |
| double maxFirst = Double.MAX_VALUE; | |
| for (Integer v : graph.adj(o1)) { | |
| if (maxFirst < graph.getWeight(o1, v)) { | |
| maxFirst = graph.getWeight(o1, v); | |
| } | |
| } | |
| return maxFirst; | |
| } | |
| } | |
| public Graph spanningTree(int source) { | |
| if (source < 0 || source >= graph.V()) { | |
| throw new IndexOutOfBoundsException(); | |
| } | |
| Graph g = new Graph(graph.V()); | |
| for (int u = 0; u < graph.V(); u++) { | |
| } | |
| PriorityQueue<Integer> q = new PriorityQueue<Integer>(graph.V(), new VertexEdgeComparator()); | |
| for (int i = 0; i < graph.V(); i++) { | |
| q.add(i); | |
| } | |
| while (!q.isEmpty()) { | |
| Integer u = q.poll(); | |
| for (Integer v : graph.adj(u)) { | |
| if (q.contains(v) && graph.getWeight(u, v) < distances[v]) { | |
| distances[v] = graph.getWeight(u, v); | |
| g.addUndirectedEdge(u, v); | |
| } | |
| } | |
| if (debug) { | |
| System.out.println(this); | |
| } | |
| } | |
| return g; | |
| } | |
| public static void main(String[] args) { | |
| } | |
| } |
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