Program for Mean and median of an unsorted array

Given n size unsorted array, find its mean and median.

Mean of an array = (sum of all elements) / (number of elements)

Median of a sorted array of size n is defined as the middle element when n is odd and average of middle two elements when n is even.

Since the array is not sorted here, we sort the array first, then apply above formula.

Examples:

Input  : a[] = {1, 3, 4, 2, 6, 5, 8, 7}
Output : Mean = 4.5
         Median = 4.5
Sum of the elements is 1 + 3 + 4 + 2 + 6 + 
5 + 8 + 7 = 36
Mean = 36/8 = 4.5
Since number of elements are even, median
is average of 4th and 5th largest elements.
which means (4 + 5)/2 = 4.5

Input  : a[] = {4, 4, 4, 4, 4}
Output : Mean = 4
         Median = 4

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Below is the code implementation:

C++

// CPP program to find mean and median of  
// an array 
#include <bits/stdc++.h> 
using namespace std; 
  
// Function for calculating mean 
double findMean(int a[], int n) 
{ 
    int sum = 0; 
    for (int i = 0; i < n; i++)  
        sum += a[i]; 
      
    return (double)sum/(double)n; 
} 
  
// Function for calculating median 
double findMedian(int a[], int n) 
{ 
    // First we sort the array 
    sort(a, a+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; 
} 
  
// Driver program 
int main() 
{ 
    int a[] = { 1, 3, 4, 2, 7, 5, 8, 6 }; 
    int n = sizeof(a)/sizeof(a[0]); 
    cout << "Mean = " << findMean(a, n) << endl;  
    cout << "Median = " << findMedian(a, n) << endl;  
    return 0; 
} 

Java

// Java program to find mean  
// and median of an array 
import java.util.*; 
  
class GFG 
{ 
    // Function for calculating mean 
    public static double findMean(int a[], int n) 
    { 
        int sum = 0; 
        for (int i = 0; i < n; i++)  
            sum += a[i]; 
      
        return (double)sum / (double)n; 
    } 
  
    // Function for calculating median 
    public static double findMedian(int a[], int n) 
    { 
        // First we sort the array 
        Arrays.sort(a); 
  
        // check for even case 
        if (n % 2 != 0) 
        return (double)a[n / 2]; 
      
        return (double)(a[(n - 1) / 2] + a[n / 2]) / 2.0; 
    } 
  
    // Driver program 
    public static void main(String args[]) 
    { 
        int a[] = { 1, 3, 4, 2, 7, 5, 8, 6 }; 
        int n = a.length; 
        System.out.println("Mean = " + findMean(a, n));  
        System.out.println("Median = " + findMedian(a, n));  
    } 
} 
  
// This article is contributed by Anshika Goyal. 

Python3

# Python3 program to find mean  
# and median of an array 
  
# Function for calculating mean 
def findMean(a, n): 
  
    sum = 0
    for i in range( 0, n): 
        sum += a[i] 
      
    return float(sum/n) 
  
# Function for calculating median 
def findMedian(a, n): 
  
    # First we sort the array 
    sorted(a) 
  
    # check for even case 
    if n % 2 != 0: 
        return float(a[n/2]) 
      
    return float((a[int((n-1)/2)] +
                  a[int(n/2)])/2.0) 
  
# Driver program 
a = [ 1, 3, 4, 2, 7, 5, 8, 6 ] 
n = len(a) 
print("Mean =", findMean(a, n)) 
print("Median =", findMedian(a, n)) 
  
# This code is contributed by Smitha Dinesh Semwal 

C#

// C# program to find mean  
// and median of an array 
using System; 
  
class GFG 
{ 
    // Function for  
    // calculating mean 
    public static double findMean(int []a,  
                                  int n) 
    { 
        int sum = 0; 
        for (int i = 0; i < n; i++)  
            sum += a[i]; 
      
        return (double)sum /  
               (double)n; 
    } 
  
    // Function for  
    // calculating median 
    public static double findMedian(int []a, 
                                    int n) 
    { 
        // First we sort 
        // the array 
        Array.Sort(a); 
  
        // check for  
        // even case 
        if (n % 2 != 0) 
        return (double)a[n / 2]; 
      
        return (double)(a[(n - 1) / 2] +  
                        a[n / 2]) / 2.0; 
    } 
  
    // Driver Code 
    public static void Main() 
    { 
        int []a = {1, 3, 4, 2,  
                   7, 5, 8, 6}; 
        int n = a.Length; 
        Console.Write("Mean = " +  
                       findMean(a, n) +  
                                 "\n");  
        Console.Write("Median = " +  
                       findMedian(a, n) +  
                                   "\n");  
    } 
} 
  
// This code is contributed by Smitha . 

PHP

<?php  
// PHP program to find mean  
// and median of an array 
  
// Function for calculating mean 
function findMean(&$a, $n) 
{ 
    $sum = 0; 
    for ($i = 0; $i < $n; $i++)  
        $sum += $a[$i]; 
      
    return (double)$sum /  
           (double)$n; 
} 
  
// Function for  
// calculating median 
function findMedian(&$a, $n) 
{ 
    // First we sort the array 
    sort($a); 
  
    // check for even case 
    if ($n % 2 != 0) 
    return (double)$a[$n / 2]; 
      
    return (double)($a[($n - 1) / 2] + 
                    $a[$n / 2]) / 2.0; 
} 
  
// Driver Code 
$a = array(1, 3, 4, 2,  
           7, 5, 8, 6); 
$n = sizeof($a); 
echo "Mean = " .  
      findMean($a, $n)."\n";  
echo "Median = " .  
      findMedian($a, $n);  
  
// This code is contributed 
// by ChitraNayal 
?> 

Output:

Mean = 4.5
Median = 4.5

Time Complexity to find mean = O(n)
Time Complexity to find median = O(n Log n) as we need to sort the array first. Note that we can find median in O(n) time using methods discussed here and here.

This article is contributed by Himanshu Ranjan. 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.

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My Personal Notes

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

C++

Java

Python3

C#

PHP

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