First element to occur k times Java

PROGRAM TO PRINT THE FIRST ELEMENT OCCURRING K TIMES IN AN ARRAY

import java.util.HashMap;

  

// Java implementation to find first

// element occurring k times

class MAIN {

  

// function to find the first element

// occurring k number of times

    static int firstElement(int arr[], int n, int k) {

        // unordered_map to count

        // occurrences of each element

  

        HashMap<Integer, Integer> count_map = new HashMap<>();

        for (int i = 0; i < n; i++) {

            int a = 0;

            if(count_map.get(arr[i])!=null){

                a = count_map.get(arr[i]);

            }

              

            count_map.put(arr[i], a+1);

        }

        //count_map[arr[i]]++;

  

        for (int i = 0; i < n; i++) // if count of element == k ,then

        // it is the required first element 

        {

            if (count_map.get(arr[i]) == k) {

                return arr[i];

            }

        }

  

        // no element occurs k times

        return -1;

    }

  

// Driver program to test above

    public static void main(String[] args) {

        int arr[] = {1, 7, 4, 3, 4, 8, 7};

        int n = arr.length;

        int k = 2;

        System.out.println(firstElement(arr, n, k));

    }

}







OUTPUT

7

CREDITS: https://www.geeksforgeeks.org/first-element-occurring-k-times-array/