# Java Programs 17: Java Program to Find Duplicate Elements in Each Row of 2D Array

Hello Programers,

### Problem:

How to find duplicate values in each row of 2D array. For example , we have 2d array as below:

 4 67 34 90 9 4 11 100 6 12 9 4 78 87 4 2

Output should be : 4 , Because 4 is common in each row.

### Solution:

This was really brainstorming as I want to avoid multiple for loops to solve this problem. My logic to solve above problem is as below:

1. I assume all elements in first row are duplicate elements i.e. exists in all rows.
2. I store all elements of first row in a HashSet say firstRow. I used HashSet just to add only unique elements as a row can have duplicate elements as well.
3. Now I take all elements of second row and store them in a different HashSet say secondRow.
4. Now I take intersection of firstRow and secondRow. It will return me only elements which are common in both rows.
5. If size of firstRow is zero, we will stop further iteration as it means there is no element which is common in all rows.
6. If size of firstRow is not zero, repeat step 4 for next row i.e. 3rd row.

### Java Programs:

```package Arrays;

import java.util.HashSet;
import java.util.Set;

public class DuplicateElementInRows {

public static void main(String[] args) {

// An input array
int arrayValues[][] = { { 4, 67, 34, 90 }, { 9, 4, 11, 100 }, { 6, 12, 9, 4 }, { 78, 87, 4, 2 } };

// A set to store expected duplicates
Set<Integer> expectedDuplicates = new HashSet<Integer>();

// To store next row elements
Set<Integer> deleteRow = new HashSet<Integer>();

boolean duplicates=true;

// Iteration starts from here
for (int i = 0; i < arrayValues.length; i++) {
// This will work for if every row has different number of elements
for (int j = 0; j < arrayValues[i].length; j++) {
// Assuming elements of first row are duplicates
if (i == 0)

// If not first row, add in another HashSet
else {
}

}

// Intersection should be avoided for first row
if (i != 0) {
// Intersection of two sets
expectedDuplicates.retainAll(deleteRow);
// Emptying deleteRow
deleteRow.clear();

// Check if intersection makes expectedDuplicates size 0.
if (expectedDuplicates.size() == 0) {
duplicates=false;
break;
}
}

}

// Printing Duplicates
if(duplicates)
System.out.println("Duplicated elemets in all rows: "+expectedDuplicates);
else
System.out.println("There is no duplicate elements.");

}
}

```

Output:

Hope it will be easy to understand for you guys. If not feel free to comment.

If you have any different way to solve above problem please comment. It will be learning for everyone.

If you like my posts, please like, comment, share and subscribe.

#HappyCoding

#### Author: Amod Mahajan

My name is Amod Mahajan and I am an IT employee with 6+ years of experience in Software testing and staying in Bengaluru. My area of interest is Automation testing. I started from basics and went through so many selenium tutorials. Thanks to Mukesh Otwani as his tutorials are easy and cover basics to advance. I have habit of exploring concepts by deep diving. I used to make notes. I thought of sharing my knowledge through posts and now I am here. #KeepLearning #ShareLearning