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

• Difficulty Level : Medium
• Last Updated : 12 May, 2021

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, initialize 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++

 `// C++ implementation to find first K``// elements whose difference with the``// median of array is maximum` `#include ``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);` `    ``kStrongest(arr, n, k);``    ``return` `0;``}`

## Java

 `// 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`

## Python3

 `# 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`

## C#

 `// 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`

## Javascript

 ``
Output:
`5 1 4` My Personal Notes arrow_drop_up