Find K elements whose absolute difference with median of array is maximum

Given an array arr[] and an integer K, the task is to find the K elements of the array whose absolute difference with median of array is maximum. 
Note: If two elements have equal difference then the maximum element is taken into consideration.
Examples: 
 

Input : arr[] = {1, 2, 3, 4, 5}, k = 3 
Output : {5, 1, 4} 
Explanation : 
Median m = 3, 
Difference of each array elements from median, 
1 ==> diff(1-3) = 2 
2 ==> diff(2-3) = 1 
3 ==> diff(3-3) = 0 
4 ==> diff(4-3) = 1 
5 ==> diff(5-3) = 2 
First K elements are 5, 1, 4 in this array.
Input: arr[] = {1, 2, 3}, K = 2 
Output: {3, 1} 
 

 

Approach: 
 

  • Sort the array and find the median of the array
  • Create a difference array to store the difference of each element with the median of the sorted array.
  • Highest difference elements will be the corner elements of the array. Therefore, intialize the two pointers as both the corner elements of the array that is 0 and N – 1.
  • Finally include the elements of the array one by one with the maximum difference with the median.

Below is the implementation of the above approach:
 

C++

filter_none

edit
close

play_arrow

link
brightness_4
code

// C++ implementation to find first K
// elements whose difference with the 
// median of array is maximum
  
#include <bits/stdc++.h>
using namespace std;
  
// Function for calculating median 
double findMedian(int a[], int n) 
{
    // check for even case 
    if (n % 2 != 0) 
       return (double)a[n/2]; 
        
    return (double)(a[(n-1)/2] + a[n/2])/2.0; 
} 
  
// Function to find the K maximum absolute
// difference with the median of the array
void kStrongest(int arr[], int n, int k)
{
    // Sort the array.
    sort(arr, arr + n);
  
    // Store median
    double median = findMedian(arr, n);
    int diff[n];
  
    // Find and store difference
    for (int i = 0; i < n; i++) {
        diff[i] = abs(median - arr[i]);
    }
  
    int i = 0, j = n - 1;
    while (k > 0) {
          
        // If diff[i] is greater print it
        // Else print diff[j]
        if (diff[i] > diff[j]) {
            cout << arr[i] << " ";
            i++;
        }
        else {
            cout << arr[j] << " ";
            j--;
        }
        k--;
    }
}
  
// Driver Code
int main()
{
    int arr[] = { 1, 2, 3, 4, 5 };
    int k = 3;
    int n = sizeof(arr) / sizeof(arr[0]);
  
    kStrongest(arr, n, k);
    return 0;
}

chevron_right






                        filter_none









Java














                                    filter_none




                                    edit

                                    close




                                    play_arrow




                                    link

                                    brightness_4

                                    code
                                




















// Java implementation to find first K 


// elements whose difference with the  


// median of array is maximum 


import java.util.*; 


class GFG{ 


   


// Function for calculating median  


static double findMedian(int a[], int n)  


{ 


    // check for even case  


    if (n % 2 != 0)  


       return (double)a[n / 2];  


         


    return (double)(a[(n - 1) / 2] +  


                    a[n / 2]) / 2.0;  


}  


   


// Function to find the K maximum absolute 


// difference with the median of the array 


static void kStrongest(int arr[], int n, int k) 


{ 


    // Sort the array. 


    Arrays.sort(arr); 


   


    // Store median 


    double median = findMedian(arr, n); 


    int []diff = new int[n]; 


   


    // Find and store difference 


    for (int i = 0; i < n; i++)  


    { 


        diff[i] = (int)Math.abs(median - arr[i]); 


    } 


   


    int i = 0, j = n - 1; 


    while (k > 0)  


    { 


           


        // If diff[i] is greater print it 


        // Else print diff[j] 


        if (diff[i] > diff[j]) 


        { 


            System.out.print(arr[i] + " "); 


            i++; 


        } 


        else 


        { 


            System.out.print(arr[j] + " "); 


            j--; 


        } 


        k--; 


    } 


} 


   


// Driver Code 


public static void main(String[] args) 


{ 


    int arr[] = { 1, 2, 3, 4, 5 }; 


    int k = 3; 


    int n = arr.length; 


   


    kStrongest(arr, n, k); 


} 


} 


// This code is contributed by sapnasingh4991



















                        chevron_right







                        filter_none









Python3














                                    filter_none




                                    edit

                                    close




                                    play_arrow




                                    link

                                    brightness_4

                                    code
                                




















# Python3 program to find first K 


# elements whose difference with the 


# median of array is maximum 


  


# Function for calculating median 


def findMedian(a, n): 


      


    # Check for even case 


    if (n % 2 != 0): 


        return a[int(n / 2)] 


          


    return (a[int((n - 1) / 2)] + 


            a[int(n / 2)]) / 2.0


  


# Function to find the K maximum  


# absolute difference with the  


# median of the array 


def kStrongest(arr, n, k): 


      


    # Sort the array 


    arr.sort() 


      


    # Store median 


    median = findMedian(arr, n) 


    diff = [0] * (n) 


      


    # Find and store difference 


    for i in range(n): 


        diff[i] = abs(median - arr[i]) 


          


    i = 0


    j = n - 1


      


    while (k > 0): 


          


        # If diff[i] is greater print  


        # it. Else print diff[j] 


        if (diff[i] > diff[j]): 


            print(arr[i], end = " ") 


            i += 1


        else: 


            print(arr[j], end = " ") 


            j -= 1


          


        k -= 1


      


# Driver code 


arr = [ 1, 2, 3, 4, 5 ] 


k = 3


n = len(arr) 


  


kStrongest(arr, n, k) 


  


# This code is contributed by sanjoy_62 



















                        chevron_right







                        filter_none









C#














                                    filter_none




                                    edit

                                    close




                                    play_arrow




                                    link

                                    brightness_4

                                    code
                                




















// C# implementation to find first K 


// elements whose difference with the  


// median of array is maximum 


using System; 


  


class GFG{ 


  


// Function for calculating median  


static double findMedian(int []a, int n)  


{ 


    // Check for even case  


    if (n % 2 != 0)  


        return (double)a[n / 2];  


          


    return (double)(a[(n - 1) / 2] +  


                    a[n / 2]) / 2.0;  


}  


  


// Function to find the K maximum absolute 


// difference with the median of the array 


static void kStrongest(int []arr, int n, 


                                  int k) 


{ 


      


    // Sort the array. 


    Array.Sort(arr); 


      


    int i = 0; 


      


    // Store median 


    double median = findMedian(arr, n); 


    int []diff = new int[n]; 


  


    // Find and store difference 


    for(i = 0; i < n; i++)  


    { 


       diff[i] = (int)Math.Abs(median - arr[i]); 


    } 


  


    int j = n - 1; 


    i = 0; 


    while (k > 0)  


    { 


          


        // If diff[i] is greater print it 


        // Else print diff[j] 


        if (diff[i] > diff[j]) 


        { 


            Console.Write(arr[i] + " "); 


            i++; 


        } 


        else


        { 


            Console.Write(arr[j] + " "); 


            j--; 


        } 


        k--; 


    } 


} 


  


// Driver Code 


public static void Main(String[] args) 


{ 


    int []arr = { 1, 2, 3, 4, 5 }; 


    int k = 3; 


    int n = arr.Length; 


  


    kStrongest(arr, n, k); 


} 


} 


  


// This code is contributed by Rohit_ranjan 



















                        chevron_right







                        filter_none











Output:


5 1 4




competitive-programming-img





    

        My Personal Notes
        arrow_drop_up
    

    

        
        

            
            
        

    


Recommended Posts:
manoj_n
Check out this Author's contributed articles.
If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please Improve this article if you find anything incorrect by clicking on  the "Improve Article" button below.


Improved By :  Rohit_ranjan, sanjoy_62