Dijkstra's algorithm in recursion in Java

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I am computing travelling salesman problem. I have function as follow:

    public static double dijkstry(city source, city[] cities){
    double min = Double.MAX_VALUE, k;
    city[] tmp = new city[2]; //temporary array of city's
    tmp[0]=source;
    city zm = null;
    for(city c : cities){
        tmp[1]=c;
        k = cost(tmp);
        if(k<min&&k!=0){
            min=k;
            zm=c;
        }
    }

    if(zm!=null||city!=null)
        min+=dijkstry(zm,remain(zm,cities));
    else
        min=0;

    return min;
}

where cost function is a function to compute length beetwen two cities (in km), remain function return collection of the other cities to visit. It's look good, but even I have if statement preventing from Null pointer exception, I still have this exception.

How to use dijkstra's algorithm in one simple Java function where I already have data like collection of the other cities?

asked 40 secs ago

ElConrado

13

Dijkstra's algorithm in recursion in Java