Given a number n. The problem is to efficiently check whether n is a multiple of 4 or not without using arithmetic operators.
Examples:
Input : 16
Output : Yes
Input : 14
Output : No
Approach: A multiple of 4 always has 00 as its last two digits in its binary representation. We have to check whether the last two digits of n are unset or not.
How to check whether the last two bits are unset or not.
If n & 3 == 0, then the last two bits are unset, else either both or one of them are set.
C++
#include <bits/stdc++.h>
using namespace std;
string isAMultipleOf4( int n)
{
if ((n & 3) == 0)
return "Yes" ;
return "No" ;
}
int main()
{
int n = 16;
cout << isAMultipleOf4(n);
return 0;
}
|
Java
class GFG {
static boolean isAMultipleOf4( int n)
{
if ((n & 3 ) == 0 )
return true ;
return false ;
}
public static void main(String[] args)
{
int n = 16 ;
System.out.println(isAMultipleOf4(n) ? "Yes" : "No" );
}
}
|
Python 3
def isAMultipleOf4(n):
if ((n & 3 ) = = 0 ):
return "Yes"
return "No"
if __name__ = = "__main__" :
n = 16
print (isAMultipleOf4(n))
|
C#
using System;
class GFG {
static bool isAMultipleOf4( int n)
{
if ((n & 3) == 0)
return true ;
return false ;
}
public static void Main()
{
int n = 16;
Console.WriteLine(isAMultipleOf4(n) ? "Yes" : "No" );
}
}
|
PHP
<?php
function isAMultipleOf4( $n )
{
if (( $n & 3) == 0)
return "Yes" ;
return "No" ;
}
$n = 16;
echo isAMultipleOf4( $n );
?>
|
Javascript
<script>
function isAMultipleOf4(n)
{
if ((n & 3) == 0)
return true ;
return false ;
}
let n = 16;
document.write(isAMultipleOf4(n) ? "Yes" : "No" );
</script>
|
Output:
Yes
Time Complexity : O(1)
Auxiliary Space: O(1)
Can we generalize above solution?
Similarly we can check for other powers of 2. For example, a number n would be multiple of 8 if n & 7 is 0. In general we can say.
// x must be a power of 2 for below
// logic to work
if (n & (x -1) == 0)
n is a multiple of x
Else
n is NOT a multiple of x
If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.
Feeling lost in the world of random DSA topics, wasting time without progress? It's time for a change! Join our DSA course, where we'll guide you on an exciting journey to master DSA efficiently and on schedule.
Ready to dive in? Explore our Free Demo Content and join our DSA course, trusted by over 100,000 geeks!
Last Updated :
15 Jul, 2022
Like Article
Save Article