Position of rightmost different bit

Given two numbers m and n. Find the position of the rightmost different bit in the binary representation of numbers. It is guaranteed that such a bit exists.

Examples :

Input : m = 11, n = 9
Output : 2
(11)10 = (1011)2
(9)10 = (1001)2
It can be seen that 2nd bit from
the right is different 

Input : m = 52, n = 4
Output : 5
(52)10 = (110100)2
(4)10 = (100)2, can also be written as
     = (000100)2
It can be seen that 5th bit from
the right is different            

Approach: Get the bitwise xor of m and n. Let it be xor_value = m ^ n. Now, find the position of rightmost set bit in xor_value.

Explanation: The bitwise xor operation produces a number which has set bits only at the positions where the bits of m and n differ. Thus, the position of rightmost set bit in xor_value gives the position of rightmost different bit.

C++

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// C++ implementation to find the position
// of rightmost different bit
#include <bits/stdc++.h>
using namespace std;
   
// Function to find the position of 
// rightmost set bit in 'n'
int getRightMostSetBit(int n)
{
    return log2(n & -n) + 1;
}
   
// Function to find the position of 
// rightmost different bit in the 
// binary representations of 'm' and 'n'
int posOfRightMostDiffBit(int m, int n)
{
    // position of rightmost different
    //  bit
    return getRightMostSetBit(m ^ n);
}
   
// Driver program
int main()
{
    int m = 52, n = 4;
    cout << posOfRightMostDiffBit(m, n);
    return 0;     

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Java

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// Java implementation to find the position
// of rightmost different bit
  
class GFG {
      
    // Function to find the position of
    // rightmost set bit in 'n'
    static int getRightMostSetBit(int n) 
    {
        return (int)((Math.log10(n & -n)) / Math.log10(2)) + 1;
    }
      
    // Function to find the position of
    // rightmost different bit in the
    // binary representations of 'm' and 'n'
    static int posOfRightMostDiffBit(int m, int n) 
    {
        // position of rightmost different bit
        return getRightMostSetBit(m ^ n);
    }
      
    // Driver code
    public static void main(String arg[])
    {
        int m = 52, n = 4;
        System.out.print("Position = "
            posOfRightMostDiffBit(m, n));
    }
}
  
// This code is contributed by Anant Agarwal.

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Python3

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# Python implementation
# to find the position
# of rightmost different bit
  
import math
  
# Function to find the position of 
# rightmost set bit in 'n'
def getRightMostSetBit(n):
  
    return math.log2(n & -n) + 1
  
  
# Function to find the position of 
# rightmost different bit in the 
# binary representations of 'm' and 'n'
def posOfRightMostDiffBit(m, n):
  
    # position of rightmost different
    # bit
    return getRightMostSetBit(m ^ n)
  
# Driver code
  
m = 52
n = 4
print("position = ", int(posOfRightMostDiffBit(m, n)))
  
# This code is contributed
# by Anant Agarwal.

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C#

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// C#implementation to find the position
// of rightmost different bit
using System;
  
class GFG {
      
    // Function to find the position of
    // rightmost set bit in 'n'
    static int getRightMostSetBit(int n) 
    {
        return (int)((Math.Log10(n & -n))
                       / Math.Log10(2)) + 1;
    }
      
    // Function to find the position of
    // rightmost different bit in the
    // binary representations of 'm' and 'n'
    static int posOfRightMostDiffBit(int m, int n) 
    {
        // position of rightmost different bit
        return getRightMostSetBit(m ^ n);
    }
      
    // Driver code
    public static void Main()
    {
        int m = 52, n = 4;
        Console.Write("Position = "
            posOfRightMostDiffBit(m, n));
    }
}
  
// This code is contributed by Smitha.

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PHP

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<?php
// PHP implementation to 
// find the position of
// rightmost different bit
  
// Function to find the position 
// of rightmost set bit in 'n'
function getRightMostSetBit($n)
{
    return log($n & -$n, (2)) + 1;
}
  
// Function to find the position of 
// rightmost different bit in the 
// binary representations of 'm' 
// and 'n'
function posOfRightMostDiffBit($m, $n)
{
      
    // position of rightmost
    // different bit
    return getRightMostSetBit($m ^ $n);
}
  
    // Driver Code
    $m = 52;
    $n = 4;
    echo posOfRightMostDiffBit($m, $n);
          
// This code is contributed by Ajit
?>

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Output:

5

Using ffs() function

C++

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// C++ implementation to find the
// position of rightmost different
// bit in two number.
#include <bits/stdc++.h>
using namespace std;
   
// function to find rightmost different
//  bit in two numbers.
int posOfRightMostDiffBit(int m, int n)
{
    return ffs(m ^ n);
}
   
// Driver code
int main()
{
    int m = 52, n = 4;
    cout <<"Position = " << 
         posOfRightMostDiffBit(m, n);
    return 0; 

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PHP

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<?php
// PHP implementation to find the
// position of rightmost different
// bit in two number.
  
// function to find rightmost 
// different bit in two numbers.
function posOfRightMostDiffBit($m, $n)
{
    $t = floor(log($m ^ $n, 2));
    return $t;
}
  
// Driver code
$m = 52;
$n = 4;
echo "Position = "
    posOfRightMostDiffBit($m, $n);
  
// This code is contributed by ajit
?>

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Output :

Position = 5

This article is contributed by Ayush Jauhari. 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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