Lists in HashMap in JAVA example ,ZOHO Technical Round Question,Maps usage in java - UCS

Question:

Program for Finding all the duplicate entries in an array and print the indexes using JAVA. This is also a question asked in ZOHO software developer interview.

I have written the solution for this question using JAVA collections.

import java.io.*;

import java.util.*;

import java.text.*;

import java.math.*;

import java.util.regex.*;

public class Solution {

 public static void main(String[] args) {

     Scanner s = new Scanner(System.in);

     List <Integer> l = new ArrayList<>();

     HashMap<Integer,ArrayList<Integer> > hm = new HashMap<>();

     int n,r;

     n=s.nextInt();

     for(int i=0;i<n;i++)

     {

        r = s.nextInt();

        l.add(r);

     }

    for(int i=0;i<n;i++)

    {

        ArrayList<Integer>l1 = new ArrayList<>();

        l1.add(i);

        int p= l.get(i);

        if(hm.get(p)==null)

        hm.put(p,l1);

        else

        {

          l1 = hm.get(p);

            l1.add(i);

            hm.put(p,l1);

        }

    }

Iterator<Map.Entry<Integer,ArrayList<Integer> > >itr = hm.entrySet().iterator();

     while(itr.hasNext())

     {

          HashMap.Entry<Integer,ArrayList<Integer> >mp = itr.next();

        int k = mp.getKey();

         ArrayList <Integer> l3 = mp.getValue();

         System.out.printf("%d :",k);

         if(l3.size()>1)

         {

        for(int p=1;p<l3.size();p++)

        {

            System.out.printf("%d ",l3.get(p));

        }

         }

         else

         {

             System.out.printf("no duplicates");

         }

         System.out.printf("\n");

     }

   }

}

>

Input (stdin)

6
1
2
2
2
4
4

Your Output (stdout)

1 :no duplicates
2 :2 3 
4 :5 

Pairs in  TreeSet tutorial  along with overriding sorting for our  usage:

https://www.unleashcodingskills.com/2018/05/pairs-in-treeset-java-sorting-pairs-in.html

Happy Coding...................

Happy Coding............