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Choose n elements such that their mean is maximum

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  • Difficulty Level : Basic
  • Last Updated : 13 Sep, 2022
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Given an array of 2 * n elements, the task is to construct and print an array of n elements such that the mean of the new array is maximum. Here n is even.

Examples: 

Input: arr[] = {3, 1, 2, 3, 8, 6} 
Output: 3 6 8

Input: arr[] = {3, 2, 3, 8} 
Output: 3 8 

Approach: Mean of an array is the average of the elements of the same array i.e (∑arr[i]) / n. So, in order for the mean of the array to be maximum, choose the maximum n elements from the array, this can be done by first sorting the array and then choosing the elements starting from the maximum.

Below is the implementation of the above approach: 

C++




// C++ implementation of the approach
#include <bits/stdc++.h>
using namespace std;
 
// Utility function to print the contents
// of an array
void printArray(int arr[], int n)
{
    for (int i = 0; i < n; i++)
        cout << arr[i] << " ";
}
 
// Function to print the array with
// maximum mean
void printMaxMean(int arr[], int n)
{
    int newArr[n];
 
    // Sort the original array
    sort(arr, arr + 2 * n);
 
    // Construct new array
    for (int i = 0; i < n; i++)
        newArr[i] = arr[i + n];
 
    // Print the resultant array
    printArray(newArr, n);
}
 
// Driver code
int main()
{
    int arr[] = { 4, 8, 3, 1, 3, 7, 0, 4 };
    int n = sizeof(arr) / sizeof(arr[0]);
    printMaxMean(arr, n / 2);
 
    return 0;
}

Java




// Java implementation of the approach
import java.util.Arrays;
 
class GfG{
 
    // Utility function to print the 
    // contents of an array
    static void printArray(int arr[], int n)
    {
        for (int i = 0; i < n; i++)
            System.out.print(arr[i] + " ");
    }
     
    // Function to print the array 
    // with maximum mean
    static void printMaxMean(int arr[], int n)
    {
        int newArr[] = new int[n];
     
        // Sort the original array
        Arrays.sort(arr, 0, 2 * n);
     
        // Construct new array
        for (int i = 0; i < n; i++)
            newArr[i] = arr[i + n];
     
        // Print the resultant array
        printArray(newArr, n);
    }
 
    // Driver code
    public static void main(String []args)
    {
        int arr[] = { 4, 8, 3, 1, 3, 7, 0, 4 };
        int n = arr.length;
        printMaxMean(arr, n / 2);
    }
}
 
// This code is contributed by
// Rituraj Jain

Python3




# Python3 implementation of the approach
 
# Utility function to print the contents
# of an array
def printArray(arr, n) :
    for i in range(n) :
        print(arr[i], end = " ")
 
# Function to print the array with
# maximum mean
def printMaxMean(arr, n) :
    newArr = [0] * n
 
    # Sort the original array
    arr.sort()
 
    # Construct new array
    for i in range(n) :
        newArr[i] = arr[i + n]
 
    # Print the resultant array
    printArray(newArr, n)
 
# Driver code
if __name__ == "__main__" :
 
    arr = [ 4, 8, 3, 1, 3, 7, 0, 4 ]
    n = len(arr)
    printMaxMean(arr, n // 2)
 
# This code is contributed by Ryuga

C#




// C# implementation of the approach
using System;
 
class GfG
{
 
    // Utility function to print the
    // contents of an array
    static void printArray(int[] arr, int n)
    {
        for (int i = 0; i < n; i++)
            Console.Write(arr[i] + " ");
    }
     
    // Function to print the array
    // with maximum mean
    static void printMaxMean(int[] arr, int n)
    {
        int[] newArr = new int[n];
     
        // Sort the original array
        Array.Sort(arr, 0, 2 * n);
     
        // Construct new array
        for (int i = 0; i < n; i++)
            newArr[i] = arr[i + n];
     
        // Print the resultant array
        printArray(newArr, n);
    }
 
    // Driver code
    public static void Main()
    {
        int[] arr = { 4, 8, 3, 1, 3, 7, 0, 4 };
        int n = arr.Length;
        printMaxMean(arr, n / 2);
    }
}
 
// This code is contributed by Ita_c.

PHP




<?php
// PHP implementation of the approach
 
// Utility function to print the contents
// of an array
function printArray($arr, $n)
{
    for ($i = 0; $i < $n; $i++)
        echo $arr[$i] . " ";
}
 
// Function to print the array with
// maximum mean
function printMaxMean($arr, $n)
{
    $newArr[$n] = array();
 
    // Sort the original array
    sort($arr,0);
 
    // Construct new array
    for ($i = 0; $i < $n; $i++)
        $newArr[$i] = $arr[$i + $n];
 
    // Print the resultant array
    printArray($newArr, $n);
}
 
// Driver code
$arr = array(4, 8, 3, 1, 3, 7, 0, 4);
$n = sizeof($arr);
printMaxMean($arr, $n / 2);
 
// This code is contributed
// by Akanksha Rai

Javascript




<script>
// javascript implementation of the approach
 
 
    // Utility function to print the
    // contents of an array
    function printArray(arr , n) {
        for (i = 0; i < n; i++)
            document.write(arr[i] + " ");
    }
 
    // Function to print the array
    // with maximum mean
    function printMaxMean(arr , n) {
        var newArr = Array(n).fill(0);
 
        // Sort the original array
        arr.sort((a,b)=>a-b);
 
        // Construct new array
        for (i = 0; i < n; i++)
            newArr[i] = arr[i + n];
 
        // Print the resultant array
        printArray(newArr, n);
    }
 
    // Driver code
     
        var arr = [ 4, 8, 3, 1, 3, 7, 0, 4 ];
        var n = arr.length;
        printMaxMean(arr, n / 2);
 
// This code contributed by gauravrajput1
</script>

Output

4 4 7 8 

Complexity Analysis:

  • Time Complexity: O(n logn)
  • Auxiliary Space: O(1) 

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