Clustering - Stanford

ClusterS.java

import java.io.FileNotFoundException;
import java.util.*;
import java.io.File;
public class ClusterS {
    int max = 99999999;
    int ne=0;
    int nn ;
    int clusters;
    HashMap<Integer, Nodes> hm = new HashMap<>();
    ArrayList<Edge> edges = new ArrayList<>();

    void input() {

        try {
            File f = new File("C:\\Users\\vinir_000\\IdeaProjects\\Learn\\src\\input.txt");
            Scanner sc = new Scanner(f);
            //Scanner sc = new Scanner(System.in);
            nn = sc.nextInt();
            clusters = nn;
            while (sc.hasNextInt()) {
                int v1 = sc.nextInt();
                int v2 = sc.nextInt();
                int weight = sc.nextInt();
                Nodes n1 ;
                Nodes n2 ;
                if(!hm.containsKey(v1)) {
                    n1 = new Nodes(v1);
                    hm.put(v1, n1);
                }
                else
                    n1 = hm.get(v1);

                if(!hm.containsKey(v2)) {
                    n2 = new Nodes(v2);
                    hm.put(v2, n2);
                }
                else
                    n2 = hm.get(v2);

                Edge e = new Edge(n1, n2, weight);
                edges.add(e);
                ne++;
            }
            System.out.println(edges.size());
        }
        catch (Exception e){}

    }

    Nodes getParent(Nodes n)
    {
        if(n == n.parent)
            return n;
        n.parent = getParent(n.parent);
        return n.parent;
    }


    void compute(){
        for(Edge e : edges)
        {
            Nodes px = getParent(e.n1);
            Nodes py = getParent(e.n2);
            int rx = px.rank;
            int ry = py.rank;
            if(clusters == 4 && px != py)
            {
                max = e.weight;
                break;
            }
            if(px != py && clusters != 4)
            {
                if(rx > ry)
                    py.parent = px;
                else if(rx < ry)
                    px.parent = py;
                else
                {
                    px.parent = py;
                    py.rank+=1;
                }

                clusters--;

            }
        }

    }


    public static void main(String args[])
    {
        ClusterS cs = new ClusterS();
            cs.input();
        Collections.sort(cs.edges,new SortTheEdges());
        cs.compute();
        //for(Edge e : cs.edges)
          //  System.out.println(e.n1 + " " + e.n2+" " + e.weight);

        System.out.println(cs.max);
    }

}

class SortTheEdges implements Comparator<Edge>{

    public int compare(Edge e1, Edge e2)
    {
        return e1.weight - e2.weight;
    }

}
class Edge
{
    Nodes n1;
    Nodes n2;
    int weight;
    Edge(Nodes n1,Nodes n2,int weight)
    {
        this.n1 = n1;
        this.n2 = n2;
        this.weight = weight;
    }

}

class Nodes
{
    Nodes parent;
    int vertex;
    int rank;
    Nodes(int v)
    {
        this.vertex = v;
        rank=0;
        parent = this;
    }

}