Set the rightmost unset bit

Given a non-negative number n. The problem is to set the rightmost unset bit in the binary representation of n

Examples:

Input : 21
Output : 23
(21)10 = (10101)2
Rightmost unset bit is at position 2(from right) as 
highlighted in the binary representation of 21.
(23)10 = (10111)2
The bit at position 2 has been set.

Input : 2
Output : 3

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

One method is discussed in this article

This post discusses another method.

Let the input number be n. n+1 would have all the bits flipped after the rightmost unset bit (including the unset bit). So, doing n|(n+1) would give us the required result.

C++

#include <stdio.h> 
  
// sets the rightmost unset bit 
// of n and returns the result 
int fun(unsigned int n) 
{ 
    return n | (n + 1); 
} 
  
// Driver Code 
int main() 
{ 
    int n = 5; 
    printf("The number after setting the"); 
    printf(" rightmost unset bit %d", fun(n)); 
    return 0; 
} 

Java

class GFG { 
      
    // sets the rightmost unset bit 
    // of n and returns the result 
    static int fun(int n) 
    { 
        return n | (n + 1); 
    } 
      
    // Driver Code 
    public static void main(String[] args) 
    { 
        int n = 5; 
        System.out.printf("The number "
                  + "after setting the"); 
        System.out.printf(" rightmost "
              + " unset bit %d", fun(n)); 
    } 
} 
  
// This code is contributed by Smitha 

Python3

# sets the rightmost unset bit 
# of n and returns the result 
def fun(n): 
  
    return n | (n + 1) 
  
# Driver Code 
n = 5
print("The number after setting the", end="") 
print(" rightmost unset bit ", fun(n)) 
  
# This code is contributed by Smitha 

C#

using System; 
  
class GFG { 
      
    // sets the rightmost unset bit 
    // of n and returns the result 
    static int fun(int n) 
    { 
        return n | (n + 1); 
    } 
      
    // Driver Code 
    public static void Main() 
    { 
        int n = 5; 
        Console.Write("The number "
            + "after setting the"); 
        Console.Write(" rightmost "
           + "unset bit "+ fun(n)); 
    } 
} 
  
// This code is contributed by Smitha 

PHP

<?php 
// PHP program to Set the rightmost 
// unset bit 
  
// sets the rightmost unset bit 
// of n and returns the result 
function fun($n) 
{ 
    return $n | ($n + 1); 
} 
  
    // Driver Code 
    $n = 5; 
    echo "The number after setting the"; 
    echo " rightmost unset bit ", fun($n); 
      
// This code is contributed m_kit 
?> 

Output :

The number after setting the rightmost unset bit 7

Don’t stop now and take your learning to the next level. Learn all the important concepts of Data Structures and Algorithms with the help of the most trusted course: DSA Self Paced. Become industry ready at a student-friendly price.

My Personal Notes

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

C++

Java

Python3

C#

PHP

Recommended Posts: