# Count number of bits changed after adding 1 to given N

Given an integer . The task is to find the number of bits changed after adding 1 to the given number.

Examples:

```Input : N = 5
Output : 2
After adding 1 to 5 it becomes 6.
Binary representation of 5 is 101.
Binary representation of 6 is 110.
So, no. of bits changed is 2.

Input : N = 1
Output : 2
```

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

There are three approaches to find the number of changed bits in the result obtained after adding 1 to the given value N:

• Approach 1: Add 1 to given integer and compare the bits of N and the result obtained after addition and count the number of unmatched bit.
• Approach 2: In case if 1 is added to N, then the total number of bits changed is defined by the position of 1st Zero from right i.e. LSB as zero. In the case, 1 is added to 1 then it got changed and pass a carry 1 to its next bit but if 1 is added to 0 only 0 changes to 1 and no further carry is passed.
• Approach 3: For finding number of changed bits when 1 is added to a given number take XOR of n and n+1 and calculate the number of set bits in the resultant XOR value.

Below is the implementation of the Approach 3:

## C++

 `// CPP program to find the number ` `// of changed bit ` `#include ` `using` `namespace` `std; ` ` `  `// Function to find number of changed bit ` `int` `findChangedBit(``int` `n) ` `{ ` `    ``// Calculate xor of n and n+1 ` `    ``int` `XOR = n ^ (n + 1); ` ` `  `    ``// Count set bits in xor value ` `    ``int` `result = __builtin_popcount(XOR); ` ` `  `    ``// Return the result ` `    ``return` `result; ` `} ` ` `  `// Driver function ` `int` `main() ` `{ ` `    ``int` `n = 6; ` `    ``cout << findChangedBit(n) << endl; ` ` `  `    ``n = 7; ` `    ``cout << findChangedBit(n); ` ` `  `    ``return` `0; ` `} `

## Java

 `// Java program to find the number ` `// of changed bit ` `class` `GFG  ` `{ ` ` `  `// Function to find number of changed bit ` `static` `int` `findChangedBit(``int` `n) ` `{ ` `    ``// Calculate xor of n and n+1 ` `    ``int` `XOR = n ^ (n + ``1``); ` ` `  `    ``// Count set bits in xor value ` `    ``int` `result = Integer.bitCount(XOR); ` ` `  `    ``// Return the result ` `    ``return` `result; ` `} ` ` `  `// Driver code ` `public` `static` `void` `main(String[] args)  ` `{ ` `    ``int` `n = ``6``; ` `    ``System.out.println(findChangedBit(n)); ` ` `  `    ``n = ``7``; ` `    ``System.out.println(findChangedBit(n)); ` `} ` `} ` ` `  `// This code contributed by Rajput-Ji `

## Python3

 `# Python 3 program to find the number ` `# of changed bit ` ` `  `# Function to find number of changed bit ` `def` `findChangedBit(n): ` `     `  `    ``# Calculate xor of n and n+1 ` `    ``XOR ``=` `n ^ (n ``+` `1``) ` ` `  `    ``# Count set bits in xor value ` `    ``result ``=` `bin``(XOR).count(``"1"``) ` ` `  `    ``# Return the result ` `    ``return` `result ` ` `  `# Driver Code ` `if` `__name__ ``=``=` `'__main__'``: ` `    ``n ``=` `6` `    ``print``(findChangedBit(n)) ` ` `  `    ``n ``=` `7` `    ``print``(findChangedBit(n)) ` ` `  `# This code is contributed by ` `# Surendra_Gangwar `

## C#

 `// C# program to find the number ` `// of changed bit ` `using` `System; ` `     `  `class` `GFG  ` `{ ` ` `  `// Function to find number of changed bit ` `static` `int` `findChangedBit(``int` `n) ` `{ ` `    ``// Calculate xor of n and n+1 ` `    ``int` `XOR = n ^ (n + 1); ` ` `  `    ``// Count set bits in xor value ` `    ``int` `result = bitCount(XOR); ` ` `  `    ``// Return the result ` `    ``return` `result; ` `} ` `static` `int` `bitCount(``int` `x) ` `{ ` ` `  `    ``// To store the count ` `    ``// of set bits ` `    ``int` `setBits = 0; ` `    ``while` `(x != 0)  ` `    ``{ ` `        ``x = x & (x - 1); ` `        ``setBits++; ` `    ``} ` ` `  `    ``return` `setBits; ` `} ` ` `  `// Driver code ` `public` `static` `void` `Main(String[] args)  ` `{ ` `    ``int` `n = 6; ` `    ``Console.WriteLine(findChangedBit(n)); ` ` `  `    ``n = 7; ` `    ``Console.WriteLine(findChangedBit(n)); ` `} ` `} ` ` `  `/* This code contributed by PrinciRaj1992 */`

Output:

```1
4
```

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