# 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 = 5Output: 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 = 1Output: 2

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 <bits/stdc++.h> ` `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; ` `} ` |

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## 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 ` |

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## 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 ` |

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## 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 */` |

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**Output:**

1 4

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