【图算法】狄克斯特拉算法Java实现

package cn.zhaoyuening.algorithms.dijkstra;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

class Vertex{
private String name;
private Map<Vertex, Integer> adjMap = new HashMap<>();

public Vertex(String name){
this.name = name;
}

public String getName() {
return name;
}

public Vertex setName(String name) {
this.name = name;
return this;
}

public Integer getValByVertex(Vertex vertex) {
return adjMap.get(vertex);
}

public Vertex addAdj(Vertex v, Integer val) {
adjMap.put(v, val);
return this;
}

public Set<Vertex> getAdjSet() {
return adjMap.keySet();
}

@Override
public String toString() {
return this.name;
}
}

public class Dijkstra {

private Map<Vertex, Integer> valMap;
private Set<Vertex> handledVertex;

public Integer miniVal(Vertex startVertex, Vertex endVertex) {
valMap = new HashMap<Vertex, Integer>();
valMap.put(startVertex, 0);
handledVertex = new HashSet<>();
Vertex tmpVertex = startVertex;
Set<Vertex> adjSet = null;
while (tmpVertex != null) {
handledVertex.add(tmpVertex);
adjSet = tmpVertex.getAdjSet();
for (Vertex v :
adjSet) {
updateValMap(v, valMap.get(tmpVertex)+tmpVertex.getValByVertex(v));
//                找下个最小距离点
}
tmpVertex = findMiniValVertex();
}
return valMap.get(endVertex);
}

public Vertex findMiniValVertex() {
Vertex miniVertex = null;
Integer miniVal = Integer.MAX_VALUE;
int tmpVal = 0;
for (Vertex v :
valMap.keySet()) {
if (handledVertex.contains(v)) {
continue;
}
tmpVal = valMap.get(v);
if (miniVal > tmpVal) {
miniVal = tmpVal;
miniVertex = v;
}
}
return miniVertex;
}

public boolean updateValMap(Vertex vertex,Integer val) {
if (!valMap.containsKey(vertex)||val < valMap.get(vertex)) {
valMap.put(vertex, val);
return true;
}
return false;
}

public static void main(String[] args) {
Vertex s = new Vertex("S");
Vertex a = new Vertex("A");
Vertex b = new Vertex("B");
Vertex e = new Vertex("E");

s.addAdj(a, 6);
s.addAdj(b, 2);
b.addAdj(a, 3);
a.addAdj(e, 1);

Dijkstra dijkstra = new Dijkstra();
Integer val = dijkstra.miniVal(s, e);
System.out.println(val);

}
}