Non-Repeating Element Java

PROGRAM TO FIND THE FIRST NON-REPEATING ELEMENT EFFICIENTLY 

import java.util.*;

  

class Main {

  

    static void firstNonRepeating(int arr[], int n)

    {

        // Insert all array elements in hash

        // table

        Map<Integer, Integer> m = new HashMap<>();

        for (int i = 0; i < n; i++) {

            if (m.containsKey(arr[i])) {

                m.put(arr[i], m.get(arr[i]) + 1);

            }

            else {

                m.put(arr[i], 1);

            }

        }

  

        // Traverse through map only and

        // using for-each loop for iteration over Map.entrySet()

        for (Map.Entry<Integer, Integer> x : m.entrySet())

            if (x.getValue() == 1)

                System.out.print(x.getKey() + " ");

    }

  

    // Driver code

    public static void main(String[] args)

    {

        int arr[] = { 9, 4, 9, 6, 7, 4 };

        int n = arr.length;

        firstNonRepeating(arr, n);

    }

}







OUTPUT

7 6

CREDITS: https://www.geeksforgeeks.org/non-repeating-element/