Toggle the last m bits
Given a non-negative number n. The problem is to toggle the last m bits in the binary representation of n. A toggle operation flips a bit from 0 to 1 and a bit from 1 to 0.
Constraint: 1 <= m <= n.
Examples:
Input : n = 21, m = 2 Output : 22 (21)10 = (10101)2 (22)10 = (10110)2 The last two bits in the binary representation of 21 are toggled. Input : n = 107, m = 4 Output : 100
Approach: Following are the steps:
- Calculate num = (1 << m) – 1. This will produce a number num having m bits and all will be set.
- Now, perform n = n ^ num. This will toggle the last m bits in n.
C++
// C++ implementation to // toggle the last m bits #include <bits/stdc++.h> using namespace std; // function to toggle // the last m bits unsigned int toggleLastMBits (unsigned int n, unsigned int m) { // calculating a number // 'num' having 'm' bits // and all are set. unsigned int num = (1 << m) - 1; // toggle the last m bits // and return the number return (n ^ num); } // Driver code int main() { unsigned int n = 107; unsigned int m = 4; cout << toggleLastMBits(n, m); return 0; } |
Java
// Java implementation to // toggle the last m bits import java.util.*; import java.lang.*; public class GfG{ // function to toggle // the last m bits public static int toggleLastMBits ( int n, int m) { // calculating a number // 'num' having 'm' bits // and all are set int num = ( 1 << m) - 1 ; // toggle the last m bits // and return the number return (n ^ num); } // Driver function public static void main(String argc[]){ int n = 107 ; int m = 4 ; n = toggleLastMBits(n, m); System.out.println(n); } } // This code is contributed by Sagar Shukla. |
Python3
# Python implementation to # toggle the last m bits # function to toggle # the last m bits def toggleLastMBits(n,m): # calculating a number # 'num' having 'm' bits # and all are set. num = ( 1 << m) - 1 # toggle the last m bits # and return the number return (n ^ num) # Driver code n = 107 m = 4 print (toggleLastMBits(n, m)) # This code is contributed # by Anant Agarwal. |
C#
// C# implementation to // toggle the last m bits using System; namespace Toggle { public class GFG { // Function to toggle the last m bits public static int toggleLastMBits( int n, int m) { // Calculating a number 'num' having // 'm' bits and all are set int num = (1 << m) - 1; // Toggle the last m bits // and return the number return (n ^ num); } // Driver Code public static void Main() { int n = 107, m = 4; n = toggleLastMBits(n, m); Console.Write(n); } } } // This code is contributed by Sam007. |
PHP
<?php // PHP implementation to // toggle the last m bits // function to toggle // the last m bits function toggleLastMBits( $n , $m ) { // calculating a number // 'num' having 'm' bits // and all are set. $num = (1 << $m ) - 1; // toggle the last m bits // and return the number return ( $n ^ $num ); } // Driver code { $n = 107; $m = 4; echo toggleLastMBits( $n , $m ); return 0; } // This code is contributed by nitin mittal. ?> |
Javascript
<script> // Javascript implementation to // toggle the last m bits // function to toggle // the last m bits function toggleLastMBits(n, m) { // calculating a number // 'num' having 'm' bits // and all are set. var num = (1 << m) - 1; // toggle the last m bits // and return the number return (n ^ num); } // Driver code var n = 107; var m = 4; document.write( toggleLastMBits(n, m)); </script> |
Output:
100
Time Complexity : O(1)
Auxiliary Space: O(1)