Algorithm/Disjoint Sets at master · TechRaY/Algorithm · GitHub

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import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class DisjointSet {

    static InputReader sc=new InputReader(System.in);
    static HashMap<Integer,Node> hm=new HashMap<Integer,Node>();

    class Node
    {
        int data;
        int rank;
        Node parent;

        public Node(int val)
        {
            data=val;
            rank=0;
            parent=this;
        }
    }

    public void makeSet(int val)
    {
       hm.put(val,new Node(val));
    }


    public void unionSet(int val1,int val2)
    {
        Node node1=hm.get(val1);
        Node node2=hm.get(val2);


        Node parent1=findSet(node1);
        Node parent2=findSet(node2);

        if(parent1.data==parent2.data)
        return;

        if(parent1.rank>=parent2.rank)
        {
            parent1.rank+=(parent1.rank==parent2.rank)?1:0;
            parent2.parent=parent1;
        }
        else
        parent1.parent=parent2;

    }

    public int findSet(int val)
    {
        return findSet(hm.get(val)).data;
    }


    public Node findSet(Node k)
    {
        Node parent=k.parent;

        if(parent==k)
         return parent;

        k.parent=findSet(parent);     //path compression

        return k.parent;
    }

    public static void main(String[] args)
    {
          int n=sc.nextInt();
          int m=sc.nextInt();
          int len=sc.nextInt()+1;

          Solution s=new Solution();


        for(int i=1;i<=n;i++)
        {
            s.makeSet(i);            //initially making inndividual sets
        }

        for(int i=0;i<m;i++)
        {
             int a=sc.nextInt();
             int b=sc.nextInt();

             s.unionSet(a,b);            // grouping the required sets
        }

    }
}