Skip to content
Related Articles
Set the rightmost unset bit
• Difficulty Level : Easy
• Last Updated : 05 Apr, 2021

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```

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 ` `// 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

 ``

## Javascript

 ``

Output :

`The number after setting the rightmost unset bit 7`

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.  To complete your preparation from learning a language to DS Algo and many more,  please refer Complete Interview Preparation Course.

In case you wish to attend live classes with industry experts, please refer DSA Live Classes

My Personal Notes arrow_drop_up