import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.PriorityQueue; public class DataTest { public static int INFINITY = 90000; public static Map<String,Vertex> vertexMap = new HashMap<String,Vertex>(); static class Edge{ public Vertex dest; public double cost; public Edge(Vertex d,double c){ this.dest = d; this.cost = c; } } static class Vertex implements Comparable<Vertex>{ public String name; public List<Edge> adj; public double dist; public Vertex prev; public int scratch; public boolean visited; public Vertex(String nm){ this.name = nm; adj = new ArrayList<Edge>(); reset(); } public void reset(){ visited = false; dist=DataTest.INFINITY; } @Override public int compareTo(Vertex o) { double c = o.dist; return dist < c ? -1:dist > c ? 1:0; } } public static void dijkstra(String startName){ PriorityQueue<Vertex> pq = new PriorityQueue<Vertex>();//该队列以权值升序排列，因为Vertex实现Comparable接口 Vertex start = vertexMap.get(startName); start.dist = 0; for(Vertex v:vertexMap.values()) pq.add(v); int seenNum = 0; while(!pq.isEmpty()&&seenNum < vertexMap.size()){ Vertex v = pq.remove(); System.out.println("v0---->"+v.name+":."+v.dist); if(v.scratch != 0) continue; v.scratch = 1; seenNum++; for(Edge e:v.adj){ Vertex w = e.dest; double v_to_w = e.cost; if(w.dist > v.dist + v_to_w){ w.dist = v.dist + v_to_w; w.prev = v; pq.remove(w);//出队 pq.add(w);//按优先级插在队头，先插入的在队头，依次往后 } } } System.out.println("hello !"); while(pq.peek() != null ){ System.out.println(pq.poll()); } } public static void main(String[] args){ Vertex v0 = new Vertex("v0"); Vertex v1 = new Vertex("v1"); Vertex v2 = new Vertex("v2"); Vertex v3 = new Vertex("v3"); Vertex v4 = new Vertex("v4"); Vertex v5 = new Vertex("v5"); List<Edge> e0l = v0.adj; List<Edge> e1l = v1.adj; List<Edge> e2l = v2.adj; List<Edge> e3l = v3.adj; List<Edge> e4l = v4.adj; List<Edge> e5l = v5.adj; Edge e02 = new Edge(v2,10); Edge e04 = new Edge(v4,30); Edge e05 = new Edge(v5,100); e0l.add(e04); e0l.add(e05); e0l.add(e02); Edge e12 = new Edge(v2,5); e1l.add(e12); Edge e23 = new Edge(v3,50); e2l.add(e23); Edge e35 = new Edge(v5,10); e3l.add(e35); Edge e43 = new Edge(v3,20); Edge e45 = new Edge(v5,60); e4l.add(e43); e4l.add(e45); /* 以上代码构建有向图 v0---->v5:100 v0----->V4:30 v0------>V2:10 V1------>V2:2 V2------>V3:50 V3------->V5:10 v4------->V3:20 v4------->V5:60 */ vertexMap.put("v0", v0); vertexMap.put("v1", v1); vertexMap.put("v2", v2); vertexMap.put("v3", v3); vertexMap.put("v4", v4); vertexMap.put("v5", v5); dijkstra("v0"); } }