[英]Why does my code print out 0 as the distance in dijkstras?
import java.util.*;
public class Dijkstra
{
public static class Vertex implements Comparable<Vertex>
{
public String name;
public List<Edge> adj;
public int minDistance;
public Vertex previous;
public Vertex(String argName) {
name = argName;
adj = new ArrayList<Edge>();
}
public void addEdge(Edge e) {
adj.add(e);
}
public String toString() {
return (name+"");
}
public int compareTo(Vertex other)
{
return Double.compare(minDistance, other.minDistance);
}
}
public static class Edge
{
public Vertex target;
public Vertex from;
public int weight;
public Edge(Vertex tar, int argWeight)
{ target = tar;
weight = argWeight; }
}
public static Scanner in = new Scanner(System.in);
public int numOfLines;
public static void path(Vertex source)
{
source.minDistance = 0;
PriorityQueue<Vertex> vertexQueue = new PriorityQueue<Vertex>();
vertexQueue.add(source);
while (!vertexQueue.isEmpty()) {
Vertex u = vertexQueue.poll();
for (Edge e : u.adj)
{
Vertex v = e.target;
int weight = e.weight;
int distanceThroughU = u.minDistance + weight;
if (distanceThroughU < v.minDistance) {
vertexQueue.remove(v);
v.minDistance = distanceThroughU ;
v.previous = u;
vertexQueue.add(v);
}
}
}
}
public static Vertex from,target;
public static void main(String[] args)
{
int numOfLines = Integer.parseInt(in.nextLine());
Map<String, Vertex> vertexMap = new HashMap<String, Vertex>();
boolean inVertex=true;
String line;
for(int count=0; count<numOfLines; count++){
line=in.nextLine();
String[] parts = line.split(" ");
if(!vertexMap.containsKey(parts[0]))
{
Vertex v = new Vertex(parts[0]);
vertexMap.put(parts[0], v);
}
else if(!vertexMap.containsKey(parts[1]))
{
Vertex v = new Vertex(parts[1]);
vertexMap.put(parts[1], v);
}
int weight = Integer.parseInt(parts[2]);
Vertex v = vertexMap.get(parts[0]);
if (v != null) {
v.addEdge(new Edge(vertexMap.get(parts[1]),weight));
}
}
Collection<Vertex> vertices = vertexMap.values();
for(Vertex v: vertices)
{
System.out.println(v.name+" "+(int)v.minDistance);
}
}
}
我们应该使用(v1,v2,w1)形式的输入,其中v1是主要顶点v2是目标顶点w1是权重。 一个示例输入是
10
47 28 5
28 29 3
26 79 6
28 26 2
79 26 4
28 79 9
26 47 7
29 28 2
47 29 10
29 79 1
在此(对于47到79)的输出应为9(具有路径47、28、29、79),但我却得到0
我们应该找到一条从47到79(从银到金)的最短路径,我以为我都工作了。 比它只输出最短路径的最大int值。 我不知道我在代码中哪里出错了。
感谢您提供的所有帮助。
这取决于系统中int的大小。 这是32位长的有符号整数的最大值
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