无法在Dijkstras算法中找到无限循环

Question

我试图实现Dijkstras算法然而在它的某个地方，似乎我创造了一个无限循环，我不能找到我的生活。我首先将“城市”对象排序为一系列列表，然后尝试运行dijkstras算法以找到两个城市之间的最短路径。我知道要看很多，但我在这里遇到障碍。

排序功能

public static City[] store() throws FileNotFoundException{
        File input = new File("input.txt");
        Scanner in = new Scanner(input);

        int numCities = in.nextInt();
        if(numCities < 3 || numCities > 1000){
            System.out.println("Incorrect input");
            System.exit(-1);
        }
        City[] cities = new City[numCities + 1];
        for(int i = 1; i < cities.length; i++){
            cities[i] = new City(i);
        }
        int numRoads = in.nextInt();
        if(numRoads < 2 || numRoads > 10000){
            System.out.println("Incorrect input");
            System.exit(-1);
        }
        int currCity = in.nextInt();
        int count = 3;
        while(count < cities.length){
            cities[currCity].motelPrice = in.nextInt();
            if(count < cities.length - 1)
                currCity = in.nextInt();
            count++;
        }

        while(in.hasNext()){
            City activeCity;
            currCity = in.nextInt();
            int nextCity = in.nextInt();
            int weight = in.nextInt();
            if(cities[currCity].next == null){
                cities[currCity].next = duplicate(cities, nextCity, weight);
                addCity(cities, nextCity, duplicate(cities, currCity, weight));
            }
            else{
                activeCity = cities[currCity];
                while(activeCity.next != null){
                    activeCity = activeCity.next;
                }
                activeCity.next = duplicate(cities, nextCity, weight);
                addCity(cities, nextCity, duplicate(cities, currCity, weight));
            }


        }
        for( int k = 1; k < cities.length; k++){
           System.out.print("["+k+" $"+cities[k].motelPrice+"]");
           City activeCity = cities[k];
           while(activeCity.next != null){
                activeCity = activeCity.next;
               System.out.print("($"+activeCity.nextWeight+")-->["+activeCity.cityIndex+"]");
           }
           System.out.println();
        }
        return cities;
    }

迪杰斯特拉

public static int[] dijkstra(City[] cities, int source){  
       HashSet q = new HashSet();
       for(int i = 1; i < cities.length; i++){
           q.add(cities[i]);
       }

       int[] dist = new int[cities.length];
       int[] prev = new int[cities.length];
       for (int i=0; i<dist.length; i++) {
          dist[i] = Integer.MAX_VALUE;

       }

       dist[source] = 0;

       while(q.isEmpty() == false){
           City u = new City(0);
           int x;
           int min = Integer.MAX_VALUE;
           for(int j = 0; j < dist.length; j++){
               if(dist[j] < min){
                 min = dist[j];
                 if(q.contains(cities[j])){
                    u = cities[j];
                    q.remove(u);
                    City v = u;
                    while(v.next != null){
                        v = v.next;
                        int alt = dist[u.cityIndex] + v.nextWeight; 
                        if(alt < (dist[v.cityIndex])){
                            dist[v.cityIndex] = alt;
                            prev[v.cityIndex] = u.cityIndex;
                        }
                    }            
                }
            }
           }

       }
       return dist;
   }