Binary representation of next number

Given a binary input that represents binary representation of positive number n, find binary representation of n+1.

The binary input may be and may not fit even in unsigned long long int.

Examples:

Input : 10011
Output : 10100
Here n = (19)₁₀ = (10011)₂
next greater integer = (20)₁₀ = (10100)₂ 

Input : 111011101001111111
Output : 111011101010000000

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

We store input as string so that large numbers can be handled. We traverse the string from rightmost character and convert all 1s to 0s until we find a 0. Finally convert the found 0 to 1. If we do not find a 0, we append a 1 to overall string.

string nextGreater(num)
  l = num.length

  // Find first 0 from right side. While
  // searching, convert 1s to 0s
  for i = l-1 to 0
    if num[i] == '0'
       num[i] = '1'
       break
    else
       num[i] = '0'
         
  // If there was no 0  
  if i < 0
      num = '1' + num
  return num

Below is the implementation of above idea.

C++

// C++ implementation to find the binary 
// representation of next greater integer 
#include <bits/stdc++.h> 
using namespace std; 
  
// function to find the required 
// binary representation 
string nextGreater(string num) 
{ 
    int l = num.size(); 
  
    // examine bits from the right 
    for (int i=l-1; i>=0; i--) 
    { 
        // if '0' is encountered, convert 
        // it to '1' and then break 
        if (num.at(i) == '0') 
        { 
            num.at(i) = '1'; 
            break; 
        } 
  
        // else convert '1' to '0' 
        else
            num.at(i) = '0'; 
    } 
  
    // if the binary representation 
    // contains only the set bits 
    if (i < 0) 
        num = "1" + num; 
  
    // final binary representation 
    // of the required integer 
    return num; 
} 
  
// Driver program to test above 
int main() 
{ 
    string num = "10011"; 
    cout << "Binary representation of next number = "
         << nextGreater(num); 
    return 0; 
}

Java

// Java implementation to find the binary 
// representation of next greater integer 
  
class GFG { 
  
// function to find the required 
// binary representation 
    static String nextGreater(String num) { 
  
        int l = num.length(); 
        int i; 
        // examine bits from the right 
        for (i = l - 1; i >= 0; i--) { 
            // if '0' is encountered, convert 
            // it to '1' and then break 
            if (num.charAt(i) == '0') { 
                num = num.substring(0, i) + '1' + num.substring(i+1); 
                break; 
            } // else convert '1' to '0' 
            else { 
                num = num.substring(0, i) + '0' + num.substring(i + 1); 
            } 
            // num[i] = '0'; 
        } 
  
        // if the binary representation 
        // contains only the set bits 
        if (i < 0) { 
            num = "1" + num; 
        } 
  
        // final binary representation 
        // of the required integer 
        return num; 
    } 
  
// Driver program to test above 
    public static void main(String[] args) { 
        String num = "10011"; 
        System.out.println("Binary representation of next number = "
                + nextGreater(num)); 
    } 
} 
//this code contributed by Rajput-Ji 

Python3

# Python3 implementation to find the binary 
# representation of next greater integer 
  
# function to find the required 
# binary representation 
def nextGreater(num1): 
  
    l = len(num1); 
    num = list(num1); 
  
    # examine bits from the right 
    i = l-1; 
    while(i >= 0): 
        # if '0' is encountered, convert 
        # it to '1' and then break 
        if (num[i] == '0'): 
            num[i] = '1'; 
            break; 
  
        # else convert '1' to '0' 
        else: 
            num[i] = '0'; 
        i-=1; 
  
    # if the binary representation 
    # contains only the set bits 
    num1 = ''.join(num); 
    if (i < 0): 
        num1 = '1' + num1; 
  
    # final binary representation 
    # of the required integer 
    return num1; 
  
# Driver Code 
num = "10011"; 
print("Binary representation of next number = ",nextGreater(num)); 
  
# This code is contributed by mits 

C#

      
// C# implementation to find the binary 
// representation of next greater integer 
 using System; 
public class GFG { 
   
// function to find the required 
// binary representation 
    static String nextGreater(String num) { 
   
        int l = num.Length; 
        int i; 
        // examine bits from the right 
        for (i = l - 1; i >= 0; i--) { 
            // if '0' is encountered, convert 
            // it to '1' and then break 
            if (num[i] == '0') { 
                num = num.Substring(0, i) + '1' + num.Substring(i+1); 
                break; 
            } // else convert '1' to '0' 
            else { 
                num = num.Substring(0, i) + '0' + num.Substring(i + 1); 
            } 
            // num[i] = '0'; 
        } 
   
        // if the binary representation 
        // contains only the set bits 
        if (i < 0) { 
            num = "1" + num; 
        } 
   
        // final binary representation 
        // of the required integer 
        return num; 
    } 
   
// Driver program to test above 
    public static void Main() { 
        String num = "10011"; 
        Console.WriteLine("Binary representation of next number = "
                + nextGreater(num)); 
    } 
} 
//this code contributed by Rajput-Ji 

PHP

<?php  
// PHP implementation to find the binary 
// representation of next greater integer 
  
// function to find the required 
// binary representation 
function nextGreater($num) 
{ 
    $l = strlen($num); 
  
    // examine bits from the right 
    for ($i = $l - 1; $i >= 0; $i--) 
    { 
        // if '0' is encountered, convert 
        // it to '1' and then break 
        if ($num[$i] == '0') 
        { 
            $num[$i] = '1'; 
            break; 
        } 
  
        // else convert '1' to '0' 
        else
            $num[$i] = '0'; 
    } 
  
    // if the binary representation 
    // contains only the set bits 
    if ($i < 0) 
        $num = "1" . $num; 
  
    // final binary representation 
    // of the required integer 
    return $num; 
} 
  
// Driver Code 
$num = "10011"; 
echo "Binary representation of next number = " . 
                              nextGreater($num); 
  
// This code is contributed by ita_c 
?> 

Output:

Binary representation of next number = 10100

Time Complexity : O(n) where n is number of bits in input.

This article is contributed by Ayush Jauhari. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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My Personal Notes

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

C++

Java

Python3

C#

PHP

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