Fast average of two numbers without division

Given two numbers, find floor of their average without using division.

Input : x = 10, y = 12
Output : 11

Input : x = 10, y = 7
Output : 8
We take floor of sum.

The idea is to use right shift operator, instead of doing (x + y)/2, we do (x + y) >> 1

C

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// C program to find average without using
// division.
#include <stdio.h>
  
int floorAvg(int x, int y) { 
     return (x + y) >> 1; }
  
int main() {
  int x = 10, y = 20;
  printf("\n\nAverage = %d\n\n", floorAvg(x, y));
  return 0;
}

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Java

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// Java program to find average 
// without using division
class GFG 
{
    static int floorAvg(int x, int y) {
    return (x + y) >> 1; }
      
    // Driver code
    public static void main (String[] args)
    {
        int x = 10, y = 20;
        System.out.print(floorAvg(x, y));
    }
}
  
// This code is contributed by Anant Agarwal.

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Python3

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# Python3 program to find average
# without using division.
def floorAvg(x, y):
    return (x + y) >> 1
  
# Driver code
x = 10
y = 20
  
print("Average ", floorAvg(x, y))
  
# This code is contributed by sunny singh

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C#

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// C# program to find average 
// without using division
using System;
  
class GFG 
{
    static int floorAvg(int x, int y) 
    {
      return (x + y) >> 1; 
    }
      
    // Driver code
    public static void Main (String[] args)
    {
        int x = 10, y = 20;
        Console.Write("Average = ");
        Console.Write(floorAvg(x, y));
    }
}
  
// This code is contributed by parashar...

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PHP

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<?php
// PHP program to find average
// without using division.
  
// function returns 
// the average
function floorAvg($x, $y)
    return ($x + $y) >> 1; 
      
}
  
    // Driver Code
    $x = 10;
    $y = 20;
    echo "Average = ", floorAvg($x, $y);
  
// This Code is contributed by Ajit
?>

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Output:

Average = 15

Applications :
We need floor of average of two numbers in many standard algorithms like Merge Sort, Binary Search, etc. Since we use bitwise operator instead of division, the above way of finding average is faster.



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