Compute average of two numbers without overflow

Given two numbers, a and b. Compute the average of the two numbers.
The well know formula (a + b) / 2 may fail at the following case : 
If, a = b = (2^31) – 1; i.e. INT_MAX. 
Now, (a+b) will cause overflow and hence formula (a + b) / 2 wont work 
Below is the implementation : 

C++

// C++ code to compute average of two numbers
#include <bits/stdc++.h>
using namespace std;

// Function to compute average of two numbers
int compute_average(int a, int b)
{
    return (a + b) / 2;
}

// Driver code
int main()
{
    // Assigning maximum integer value
    int a = INT_MAX, b = INT_MAX;

    // Average of two equal numbers is the same number
    cout << "Actual average : " << INT_MAX << endl;

    // Function to get the average of 2 numbers
    cout << "Computed average : " << compute_average(a, b);

    return 0;
}

Java

// Java code to compute average of two numbers

import java.io.*;

class GFG {

// Function to compute average of two numbers
static int compute_average(int a, int b)
{
    return (a + b) / 2;
}

// Driver code
    public static void main (String[] args) {

    // Assigning maximum integer value
    int a = Integer.MAX_VALUE;
    int b = Integer.MAX_VALUE;

    // Average of two equal numbers is the same number
    System.out.println("Actual average : " + Integer.MAX_VALUE);

    // Function to get the average of 2 numbers
    System.out.println("Computed average : " + compute_average(a, b));


    }
// This code is contributed by ajit.
}

Python3

# Python 3 code to compute
# average of two numbers
import sys
from math import floor

INT_MAX = 2147483647

# Function to compute
# average of two numbers
def compute_average(a, b):
    return floor((a + b) / 2)

# Driver code
if __name__ == '__main__':

    # Assigning maximum integer value
    a = INT_MAX
    b = -INT_MAX - 1

    # Average of two equal numbers
    # is the same number
    print("Actual average : ", INT_MAX)

    # Function to get the
    # average of 2 numbers
    print("Computed average : ",
           compute_average(a, b))

# This code is contributed by
# Surendra_Gangwar

C#

// C#  code to compute average of two numbers
using System;

public class GFG{

// Function to compute average of two numbers
static int compute_average(int a, int b)
{
    return (a + b) / 2;
}

// Driver code
    static public void Main (){

    // Assigning maximum integer value
    int a =int.MaxValue;
    int b = int.MaxValue;

    // Average of two equal numbers is the same number
    Console.WriteLine("Actual average : " + int.MaxValue);

    // Function to get the average of 2 numbers
    Console.WriteLine("Computed average : " + compute_average(a, b));
    }
//This code is contributed by akt_mit
}

Javascript

<script>
    // Javascript code to compute average of two numbers

    const INT_MAX = 2147483647;

    // Function to compute average of two numbers
    function compute_average(a, b)
    {
        return Math.floor((a + b) / 2);
    }

    // Assigning maximum integer value
    let a = INT_MAX;
    let b = -INT_MAX-1;

    // Average of two equal numbers is the same number
    document.write("Actual average : " + INT_MAX + "</br>");

    // Function to get the average of 2 numbers
    document.write("Computed average : " + compute_average(a, b) + "</br>");

</script>

Output:

Actual average : 2147483647
Computed average : -1

Time Complexity: O(1), the code will run in a constant time.
Auxiliary Space: O(1), no extra space is required, so it is a constant.
Improved Formula that does not cause overflow :
Average = (a / 2) + (b / 2) + (((a % 2) + (b % 2)) / 2)
Below is the implementation :

C++

// C++ code to compute average of two numbers
#include <bits/stdc++.h>
using namespace std;

// Function to compute average of two numbers
int compute_average(int a, int b)
{
    return (a / 2) + (b / 2) + ((a % 2 + b % 2) / 2);
}

// Driver code
int main()
{
    // Assigning maximum integer value
    int a = INT_MAX, b = INT_MAX;

    // Average of two equal numbers is the same number
    cout << "Actual average : " << INT_MAX << endl;

    // Function to get the average of 2 numbers
    cout << "Computed average : " << compute_average(a, b);

    return 0;
}

Java

// Java code to compute
// average of two numbers
import java.io.*;

class GFG
{

// Function to compute
// average of two numbers
static int compute_average(int a,
                           int b)
{
    return (a / 2) + (b / 2) +
           ((a % 2 + b % 2) / 2);
}

// Driver code
public static void main (String[] args)
{

// Assigning maximum
// integer value
int a = Integer.MAX_VALUE;
int b = Integer.MAX_VALUE;

// Average of two equal
// numbers is the same number
System.out.println("Actual average : " +
                     Integer.MAX_VALUE);

// Function to get the
// average of 2 numbers
System.out.print("Computed average : ");
System.out.println(compute_average(a, b));
}
}

// This code is contributed by ajit

Python3

# Python code to compute
# average of two numbers
INT_MAX=2147483647

# Function to compute
# average of two numbers
def compute_average(a,b):

    return (a // 2) + (b // 2) + ((a % 2 + b % 2) // 2)

# Driver code
if __name__ =="__main__":
    # Assigning maximum integer value
    a = INT_MAX
    b = INT_MAX

    # Average of two equal
    # numbers is the same number
    print( "Actual average : ",INT_MAX)

    # Function to get the
    # average of 2 numbers
    print( "Computed average : ",
            compute_average(a, b))


# This code is contributed
# Shubham Singh(SHUBHAMSINGH10)

C#

// C# code to compute
// average of two numbers

using System;

class GFG
{

// Function to compute
// average of two numbers
static int compute_average(int a,
                           int b)
{
    return (a / 2) + (b / 2) +
           ((a % 2 + b % 2) / 2);
}

// Driver code
public static void Main ()
{

// Assigning maximum
// integer value
int a = int.MaxValue;
int b = int.MaxValue;

// Average of two equal
// numbers is the same number
Console.Write("Actual average : " +
                     int.MaxValue+"\n");

// Function to get the
// average of 2 numbers
Console.Write("Computed average : ");
Console.Write(compute_average(a, b));
}
}

PHP

<?php
// PHP code to compute
// average of two numbers
// Function to compute
// average of two numbers
function compute_average($a,$b)
{
    return ($a / 2) + ($b / 2) +
        (($a % 2 + $b % 2) / 2);
}

// Driver code

// Assigning maximum
// integer value
$a = 2147483648;
$b = 2147483648;

// Average of two equal
// numbers is the same number
$x = 2147483648;
print("Actual average : ".$x);

// Function to get the
// average of 2 numbers
print("\nComputed average : ");
print(compute_average($a, $b));

// This code is contributed by princiraj1992
?>

Javascript

<script>

// javascript code to compute average of two numbers
const INT_MAX = 2147483647;


// Function to compute average of two numbers
function compute_average( a,  b)
{
    return parseInt(a / 2) + parseInt(b / 2) + ((a % 2 + b % 2) / 2);
}


// Driver code

    // Assigning maximum integer value
    let a = INT_MAX, b = INT_MAX;

    // Average of two equal numbers is the same number
    document.write( "Actual average : " + INT_MAX +"<br/>");

    // Function to get the average of 2 numbers
   document.write( "Computed average : " + compute_average(a, b));


// This code is contributed by todaysgaurav

</script>

Output:

Actual average : 2147483647
Computed average : 2147483647

Time Complexity: O(1), the code will run in a constant time.
Auxiliary Space: O(1), no extra space is required, so it is a constant.
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