K largest elements Java

PROGRAM TO FIND K-LARGEST/SMALLEST ELEMENTS IN A HEAP




import java.io.*;

import java.util.*;

 

class MAIN{

   

public static void FirstKelements(int arr[],

                                  int size,

                                  int k)

{

     

    // Creating Min Heap for given

    // array with only k elements

    // Create min heap with priority queue

    PriorityQueue<Integer> minHeap = new PriorityQueue<>();

    for(int i = 0; i < k; i++)

    {

        minHeap.add(arr[i]);

    }

     

    // Loop For each element in array

    // after the kth element

    for(int i = k; i < size; i++)

    {

         

        // If current element is smaller

        // than minimum ((top element of

        // the minHeap) element, do nothing

        // and continue to next element

        if (minHeap.peek() > arr[i])

            continue;

         

        // Otherwise Change minimum element

        // (top element of the minHeap) to

        // current element by polling out

        // the top element of the minHeap

        else

        {

            minHeap.poll();

            minHeap.add(arr[i]);

        }

    }

     

    // Now min heap contains k maximum

    // elements, Iterate and print

    Iterator iterator = minHeap.iterator();

     

    while (iterator.hasNext())

    {

        System.out.print(iterator.next() + " ");

    }

}

 

// Driver code

public static void main (String[] args)

{

    int arr[] = { 11, 3, 2, 1, 15, 5, 4,

                  45, 88, 96, 50, 45 };

     

    int size = arr.length;

     

    // Size of Min Heap

    int k = 3;

     

    FirstKelements(arr, size, k);

}

}

OUTPUT:

50 88 96 

CREDITS: https://www.geeksforgeeks.org/k-largestor-smallest-elements-in-an-array/