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Remove one bit from a binary number to get maximum value

  • Last Updated : 21 May, 2021

Given a binary number, the task is to remove exactly one bit from it such that, after it’s removal, the resultant binary number is greatest from all the options.
Examples: 
 

Input: 110
Output: 11
    As 110 = 6 in decimal, 
    the option is to remove either 0 or 1.
    So the possible combinations are 10, 11
    The max number is 11 = 3 in decimal.  

Input:1001
Output: 101

Approach:
 

  1. Traverse the binary number from left to right.
  2. Find the least redundant 0 bit, as this bit will have the least effect on the resultant binary number.
  3. Skip this bit, or remove it.
  4. The rest of the bits give the maximum value binary number.

Below is the implementation of the above approach:
Program: 
 

C++




// C++ program to find next maximum binary number
// with one bit removed
 
#include <bits/stdc++.h>
using namespace std;
 
// Function to find the maximum binary number
int printMaxAfterRemoval(string s)
{
    bool flag = false;
    int n = s.length();
 
    // Traverse the binary number
    for (int i = 0; i < n; i++) {
 
        // Try finding a 0 and skip it
        if (s[i] == '0' && flag == false) {
            flag = true;
            continue;
        }
        else
            cout << s[i];
    }
}
 
// Driver code
int main()
{
 
    // Get the binary number
    string s = "1001";
 
    // Find the maximum binary number
    printMaxAfterRemoval(s);
}

Java




// Java program to find next maximum binary number
// with one bit removed
 
import java.io.*;
 
class GFG {
  
// Function to find the maximum binary number
static int printMaxAfterRemoval(String s)
{
    boolean flag = false;
    int n = s.length();
 
    // Traverse the binary number
    for (int i = 0; i < n; i++) {
 
        // Try finding a 0 and skip it
        if (s.charAt(i) == '0' && flag == false) {
            flag = true;
            continue;
        }
        else
            System.out.print( s.charAt(i));
    }
  return 0;
}
 
// Driver code
    public static void main (String[] args) {
            // Get the binary number
    String s = "1001";
 
    // Find the maximum binary number
    printMaxAfterRemoval(s);
    }
}
// This code is contributed by anuj_67..

Python3




# Python3 program to find next maximum 
# binary number with one bit removed
 
# Function to find the maximum
# binary number
def printMaxAfterRemoval(s):
 
    flag = False
    n = len(s)
 
    # Traverse the binary number
    for i in range(0, n):
 
        # Try finding a 0 and skip it
        if s[i] == '0' and flag == False:
            flag = True
            continue
         
        else:
            print(s[i], end = "")
 
# Driver code
if __name__ == "__main__":
 
    # Get the binary number
    s = "1001"
 
    # Find the maximum binary number
    printMaxAfterRemoval(s)
 
# This code is contributed
# by Rituraj Jain

C#




// C# program to find next maximum
// binary number with one bit removed
using System;
 
class GFG
{
// Function to find the maximum
// binary number
static int printMaxAfterRemoval(String s)
{
    bool flag = false;
    int n = s.Length;
 
    // Traverse the binary number
    for (int i = 0; i < n; i++)
    {
 
        // Try finding a 0 and skip it
        if (s[i] == '0' && flag == false)
        {
            flag = true;
            continue;
        }
        else
            Console.Write(s[i]);
    }
    return 0;
}
 
 
// Driver Code
static void Main()
{
    // Get the binary number
    String s = "1001";
     
    // Find the maximum binary number
    printMaxAfterRemoval(s);
}
}
 
// This code is contributed by Ryuga.

PHP




<?php
// PHP program to find next maximum
// binary number with one bit removed
 
// Function to find the maximum
// binary number
function printMaxAfterRemoval($s)
{
    $flag = false;
    $n = strlen($s);
 
    // Traverse the binary number
    for ($i = 0; $i < $n; $i++)
    {
 
        // Try finding a 0 and skip it
        if ($s[$i] == '0' && $flag == false)
        {
            $flag = true;
            continue;
        }
        else
            echo $s[$i];
    }
}
 
// Driver code
 
// Get the binary number
$s = "1001";
 
// Find the maximum binary number
printMaxAfterRemoval($s);
 
// This code is contributed
// by Akanksha Rai
?>

Javascript




<script>   
    // Javascript program to find next maximum
    // binary number with one bit removed
     
    // Function to find the maximum
    // binary number
    function printMaxAfterRemoval(s)
    {
        let flag = false;
        let n = s.length;
 
        // Traverse the binary number
        for (let i = 0; i < n; i++)
        {
 
            // Try finding a 0 and skip it
            if (s[i] == '0' && flag == false)
            {
                flag = true;
                continue;
            }
            else
                document.write(s[i]);
        }
        return 0;
    }
     
    // Get the binary number
    let s = "1001";
       
    // Find the maximum binary number
    printMaxAfterRemoval(s);
     
</script>
Output: 
101

 

Time Complexity: O(n)
 

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