接受输入作为顶点

Question

我正在尝试制作一个程序，其中包含城市列表和城市之间的旅行时间。在程序中，我必须向用户询问起始位置和目的地。然后程序将使用用户输入的信息来计算起点和终点之间的最短路径。

我不知道如何让程序接受用户输入作为顶点，这样我就可以使用输入将其插入

computePaths(VERTEX_START_INPUT_HERE);

System.out.println("\nDistance to " + VERTEX_DESTINATION_INPUT_HERE + ": " + v1.minDistance);

List path = getShortestPathTo(VERTEX_DESTINATION_INPUT_HERE);

这是我遇到问题的代码的预览：

System.out.println("List of Cities:");
        for (Vertex v : vertices)
         {
        System.out.println(v);
        }
        Scanner k = new Scanner(System.in);
        System.out.println("\nEnter start location: ");
        Vertex start = k.nextLine();
        System.out.println("Enter destination: ");
        String destination = k.nextLine();
        
        computePaths(v0);
         System.out.println("\nDistance to " + v1 + ": " + v1.minDistance);
         List<Vertex> path = getShortestPathTo(v1);
         System.out.println("Path: " + path);

完整代码在这里：

import java.util.PriorityQueue;
import java.util.List;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;

class Vertex implements Comparable<Vertex>
{
    public final String name;
    public Edge[] adjacencies;
    public double minDistance = Double.POSITIVE_INFINITY;
    public Vertex previous;
    public Vertex(String argName) { name = argName; }
    public String toString() { return name; }
    public int compareTo(Vertex other)
    {
        return Double.compare(minDistance, other.minDistance);
    }

}


class Edge
{
    public final Vertex target;
    public final double weight;
    public Edge(Vertex argTarget, double argWeight)
    { target = argTarget; weight = argWeight; }
}

public class Lab9
{
    public static void computePaths(Vertex source)
    {
        source.minDistance = 0.;
        PriorityQueue<Vertex> vertexQueue = new PriorityQueue<Vertex>();
    vertexQueue.add(source);

    while (!vertexQueue.isEmpty()) {
        Vertex u = vertexQueue.poll();

            // Visit each edge exiting u
            for (Edge e : u.adjacencies)
            {
                Vertex v = e.target;
                double weight = e.weight;
                double distanceThroughU = u.minDistance + weight;
        if (distanceThroughU < v.minDistance) {
            vertexQueue.remove(v);

            v.minDistance = distanceThroughU ;
            v.previous = u;
            vertexQueue.add(v);
        }
            }
        }
    }

    public static List<Vertex> getShortestPathTo(Vertex target)
    {
        List<Vertex> path = new ArrayList<Vertex>();
        for (Vertex vertex = target; vertex != null; vertex = vertex.previous)
            path.add(vertex);

        Collections.reverse(path);
        return path;
    }

    public static void main(String[] args)
    {
    Vertex v0 = new Vertex("Harrisburg");
     Vertex v1 = new Vertex("Baltimore");
     Vertex v2 = new Vertex("Washington");
     Vertex v3 = new Vertex("Philadelphia");
     Vertex v4 = new Vertex("Binghamton");
     Vertex v5 = new Vertex("Allentown");
     Vertex v6 = new Vertex("New York");
     v0.adjacencies = new Edge[]{ new Edge(v1,  79.83),
                                  new Edge(v5,  81.15) };
     v1.adjacencies = new Edge[]{ new Edge(v0,  79.75),
                                  new Edge(v2,  39.42),
                                  new Edge(v3, 103.00) };
     v2.adjacencies = new Edge[]{ new Edge(v1,  38.65) };
     v3.adjacencies = new Edge[]{ new Edge(v1, 102.53),
                                  new Edge(v5,  61.44),
                                  new Edge(v6,  96.79) };
     v4.adjacencies = new Edge[]{ new Edge(v5, 133.04) };
     v5.adjacencies = new Edge[]{ new Edge(v0,  81.77),
                                  new Edge(v3,  62.05),
                                  new Edge(v4, 134.47),
                                  new Edge(v6,  91.63) };
     v6.adjacencies = new Edge[]{ new Edge(v3,  97.24),
                                  new Edge(v5,  87.94) };
     Vertex[] vertices = { v0, v1, v2, v3, v4, v5, v6 };

        
        System.out.println("List of Cities:");
        for (Vertex v : vertices)
     {
        System.out.println(v);
    }
        Scanner k = new Scanner(System.in);
        System.out.println("Enter start location: ");
        
        System.out.println("Enter destination: ");
        
        computePaths(v0);
         System.out.println("\nDistance to " + v1 + ": " + v1.minDistance);
         List<Vertex> path = getShortestPathTo(v1);
         System.out.println("Path: " + path);
    }
}

Answer 1

您应该将输入值分配给一个属性，类似于这个：

Scanner in = new Scanner(System.in);
System.out.println("Enter start location: ");
location = in.nextLine();
System.out.println("Enter destination: ");
destination = in.nextLine();

System.out.println("You entered location: " + location + " and destination: " +  destination + " .");

通过使用这个转换成值的输入，您可以计算它们。

Answer 2

System.out.println("List of Cities:");

        for (Vertex v : vertices)
         {
        System.out.println(v);
        }
        Scanner k = new Scanner(System.in);
        System.out.println("\nEnter start location: ");
        int start = k.nextInt();
        System.out.println("Enter destination: ");
        int destination = k.nextInt();

        computePaths(vertices[start]);
         System.out.println("\nDistance to " + vertices[destination] + ": " + vertices[destination].minDistance);
         List<Vertex> path = getShortestPathTo(vertices[destination]);
         System.out.println("Path: " + path);
    }

接受输入作为顶点

Accept input as Vertex

java

user-input

list

dijkstra