# XOR counts of 0s and 1s in binary representation

Given a number, the task is to find XOR of count of 0s and count of 1s in binary representation of a given number.

**Examples:**

Input : 5 Output : 3 Binary representation : 101 Count of 0s = 1, Count of 1s = 2 1 XOR 2 = 3. Input : 7 Output : 3 Binary representation : 111 Count of 0s = 0 Count of 1s = 3 0 XOR 3 = 3.

The idea is simple, we traverse through all bits of a number, count 0s and 1s and finally return XOR of two counts.

## C++

`// C++ program to find XOR of counts 0s and 1s in ` `// binary representation of n. ` `#include<iostream> ` `using` `namespace` `std; ` ` ` `// Returns XOR of counts 0s and 1s in ` `// binary representation of n. ` `int` `countXOR(` `int` `n) ` `{ ` ` ` `int` `count0 = 0, count1 = 0; ` ` ` `while` `(n) ` ` ` `{ ` ` ` `//calculating count of zeros and ones ` ` ` `(n % 2 == 0) ? count0++ :count1++; ` ` ` `n /= 2; ` ` ` `} ` ` ` `return` `(count0 ^ count1); ` `} ` ` ` `// Driver Program ` `int` `main() ` `{ ` ` ` `int` `n = 31; ` ` ` `cout << countXOR (n); ` ` ` `return` `0; ` `} ` |

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## Java

`// Java program to find XOR of counts 0s ` `// and 1s in binary representation of n. ` ` ` `class` `GFG { ` ` ` ` ` `// Returns XOR of counts 0s and 1s ` ` ` `// in binary representation of n. ` ` ` `static` `int` `countXOR(` `int` `n) ` ` ` `{ ` ` ` `int` `count0 = ` `0` `, count1 = ` `0` `; ` ` ` `while` `(n != ` `0` `) ` ` ` `{ ` ` ` `//calculating count of zeros and ones ` ` ` `if` `(n % ` `2` `== ` `0` `) ` ` ` `count0++ ; ` ` ` `else` ` ` `count1++; ` ` ` `n /= ` `2` `; ` ` ` `} ` ` ` `return` `(count0 ^ count1); ` ` ` `} ` ` ` ` ` `// Driver Program ` ` ` `public` `static` `void` `main(String[] args) ` ` ` `{ ` ` ` `int` `n = ` `31` `; ` ` ` `System.out.println(countXOR (n)); ` ` ` `} ` `} ` ` ` `// This code is contributed by prerna saini ` |

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## Python3

`# Python3 program to find XOR of counts 0s ` `# and 1s in binary representation of n. ` ` ` `# Returns XOR of counts 0s and 1s ` `# in binary representation of n. ` `def` `countXOR(n): ` ` ` ` ` `count0, count1 ` `=` `0` `, ` `0` ` ` `while` `(n !` `=` `0` `): ` ` ` ` ` `# calculating count of zeros and ones ` ` ` `if` `(n ` `%` `2` `=` `=` `0` `): ` ` ` `count0 ` `+` `=` `1` ` ` `else` `: ` ` ` `count1 ` `+` `=` `1` ` ` `n ` `/` `/` `=` `2` ` ` ` ` `return` `(count0 ^ count1) ` ` ` `# Driver Code ` `n ` `=` `31` `print` `(countXOR(n)) ` ` ` `# This code is contributed by Anant Agarwal. ` |

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## C#

`// C# program to find XOR of counts 0s ` `// and 1s in binary representation of n. ` `using` `System; ` ` ` `class` `GFG { ` ` ` ` ` `// Returns XOR of counts 0s and 1s ` ` ` `// in binary representation of n. ` ` ` `static` `int` `countXOR(` `int` `n) ` ` ` `{ ` ` ` `int` `count0 = 0, count1 = 0; ` ` ` `while` `(n != 0) ` ` ` `{ ` ` ` ` ` `// calculating count of zeros ` ` ` `// and ones ` ` ` `if` `(n % 2 == 0) ` ` ` `count0++ ; ` ` ` `else` ` ` `count1++; ` ` ` ` ` `n /= 2; ` ` ` `} ` ` ` ` ` `return` `(count0 ^ count1); ` ` ` `} ` ` ` ` ` `// Driver Program ` ` ` `public` `static` `void` `Main() ` ` ` `{ ` ` ` ` ` `int` `n = 31; ` ` ` ` ` `Console.WriteLine(countXOR (n)); ` ` ` `} ` `} ` ` ` `// This code is contributed by Anant Agarwal. ` |

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## PHP

`<?PHP ` `// PHP program to find XOR of ` `// counts 0s and 1s in binary ` `// representation of n. ` ` ` `// Returns XOR of counts 0s and 1s ` `// in binary representation of n. ` `function` `countXOR(` `$n` `) ` `{ ` ` ` `$count0` `= 0; ` ` ` `$count1` `= 0; ` ` ` `while` `(` `$n` `) ` ` ` `{ ` ` ` `// calculating count of ` ` ` `// zeros and ones ` ` ` `(` `$n` `% 2 == 0) ? ` `$count0` `++ :` `$count1` `++; ` ` ` `$n` `= ` `intval` `(` `$n` `/ 2); ` ` ` `} ` ` ` `return` `(` `$count0` `^ ` `$count1` `); ` `} ` ` ` `// Driver Code ` `$n` `= 31; ` `echo` `countXOR (` `$n` `); ` ` ` `// This code is contributed ` `// by ChitraNayal ` `?> ` |

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**Output:**

5

One observation is, for a number of the form **2^x – 1**, the output is always x. We can directly produce answer for this case by first checking n+1 is a power of two or not.

This article is contributed by **Shivam Pradhan (anuj_charm)**. 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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