# Evil Number

An evil number is a non-negative number that has an even number of 1s in its binary expansion. (Binary Expansion – is representation of a number in the binary numeral system or base-2 numeral system which represents numeric values using two different symbols: typically 0 (zero) and 1 (one)).

Odious Numbers: Numbers that are not Evil are called Odious Numbers. Given a number, the task is to check if it is Evil Number or Odious Numbers.
Examples :

```Input : 3
Output : Evil Number
Explanation: Binary expansion of 3 is 11,
the number of 1s in this is 2 i.e even.

Input : 16
Output : Odious Number(not an evil number)
Explanation: Binary expansion of 16 = 10000,
having number of 1s =1 i.e odd.

Input : 23
Output : Evil Number
Explanation: Binary expansion of 23 is 10111,
the number of 1s in this is 4 i.e even.
```

## C/C++

 `// C/C++ program to check if a number is ` `// Evil number or Odious Number ` `#include ` `using` `namespace` `std; ` `#include ` ` `  `// returns number of 1s from the binary number ` `int` `count_one(``int` `n) ` `{ ` `    ``int` `c_one = 0; ` `    ``while` `(n != 0) { ` `        ``int` `rem = n % 10; ` ` `  `        ``// counting 1s ` `        ``if` `(rem == 1) ` `            ``c_one = c_one + 1; ` `        ``n = n / 10; ` `    ``} ` `    ``return` `c_one; ` `} ` ` `  `// Check if number is evil or not ` `int` `checkEvil(``int` `n) ` `{ ` `    ``int` `i = 0, bin = 0, n_one = 0; ` ` `  `    ``// converting n to binary form ` `    ``while` `(n != 0) { ` `        ``// calculating remainder ` `        ``int` `r = n % 2; ` ` `  `        ``// storing the remainders in binary ` `        ``// form as a number ` `        ``bin = bin + r * (``int``)(``pow``(10, i)); ` `        ``n = n / 2; ` `    ``} ` ` `  `    ``// Calling the count_one function to count ` `    ``// and return number of 1s in bin ` `    ``n_one = count_one(bin); ` `    ``if` `(n_one % 2 == 0) ` `        ``return` `1; ` `    ``else` `        ``return` `0; ` `} ` ` `  `// Driver Code ` `int` `main(``void``) ` `{ ` `    ``int` `i, check, num; ` `    ``num = 32; ` `    ``check = checkEvil(num); ` `    ``if` `(check == 1) ` `        ``cout << num << ``" is Evil Number\n"``; ` `    ``else` `        ``cout << num << ``" is Odious Number\n"``; ` `    ``return` `0; ` `} ` ` `  `// This code is contributed by Nikita Tiwari. `

## Java

 `// Java program to check if a number is ` `// Evil number or Odious Number ` ` `  `class` `GFG { ` `    ``// returns number of 1s from the binary number ` `    ``static` `int` `count_one(``int` `n) ` `    ``{ ` `        ``int` `c_one = ``0``; ` `        ``while` `(n != ``0``) { ` `            ``int` `rem = n % ``10``; ` ` `  `            ``// counting 1s ` `            ``if` `(rem == ``1``) ` `                ``c_one = c_one + ``1``; ` `            ``n = n / ``10``; ` `        ``} ` `        ``return` `c_one; ` `    ``} ` ` `  `    ``// Check if number is evil or not ` `    ``static` `int` `checkEvil(``int` `n) ` `    ``{ ` `        ``int` `i = ``0``, bin = ``0``, n_one = ``0``; ` ` `  `        ``// converting n to binary form ` `        ``while` `(n != ``0``) { ` `            ``// calculating remainder ` `            ``int` `r = n % ``2``; ` ` `  `            ``// storing the remainders in binary ` `            ``// form as a number ` `            ``bin = bin + r * (``int``)(Math.pow(``10``, i)); ` `            ``n = n / ``2``; ` `        ``} ` ` `  `        ``// Calling the count_one function to count ` `        ``// and return number of 1s in bin ` `        ``n_one = count_one(bin); ` `        ``if` `(n_one % ``2` `== ``0``) ` `            ``return` `1``; ` `        ``else` `            ``return` `0``; ` `    ``} ` ` `  `    ``// Driver Code ` `    ``public` `static` `void` `main(String[] args) ` `    ``{ ` `        ``int` `i, check, num; ` `        ``num = ``32``; ` `        ``check = checkEvil(num); ` `        ``if` `(check == ``1``) ` `            ``System.out.println(num + ``" is Evil Number"``); ` `        ``else` `            ``System.out.println(num + ``" is Odious Number"``); ` `    ``} ` `} ` ` `  `/* This code is contributed by Mr. Somesh Awasthi */`

## Python

 `# Python program to check if a number is  ` `# Evil number or Odious number ` ` `  `# returns number of 1s from the binary number ` `def` `count_one(n): ` `    ``c_one ``=` `0` `    ``while` `n !``=` `0``: ` `        ``rem ``=` `n ``%` `10` `         `  `        ``# Counting 1s ` `        ``if` `rem ``=``=` `1``: ` `            ``c_one ``=` `c_one ``+` `1` `        ``n ``=` `n ``/` `10` `         `  `    ``return` `c_one ` ` `  `# Check if nnumber is evil or not ` `def` `checkEvil(n): ` `    ``i ``=` `0` `    ``binary ``=` `0` `     `  `    ``# Converting n to binary form ` `    ``while` `n !``=` `0``: ` `        ``r ``=` `n ``%` `2` `        ``# Calculating Remainder ` `        ``# Storing the remainders in binary ` `        ``# form as a number ` `        ``binary ``=` `binary ``+` `r``*``(``int``(``10``*``*``i)) ` `        ``n ``=` `n ``/` `2` `         `  `    ``# Calling the count_one function to count ` `    ``# and return number of 1s in bin ` `    ``n_one ``=` `count_one(binary) ` `    ``if` `n_one ``%` `2` `=``=` `0``: ` `        ``return` `True` `    ``return` `False` `     `  `# Driver Code ` `num ``=` `32` `check ``=` `checkEvil(num) ` `if` `check: ` `    ``print` `num, ``"is Evil Nummber"` `else``: ` `    ``print` `num, ``"is Odious Number"`         `         `  `# Contributed by Harshit Agrawal         `

## C#

 `// C# program to check if a number is ` `// Evil number or Odious Number ` `using` `System; ` ` `  `class` `GFG { ` ` `  `    ``// Returns number of 1s from ` `    ``// the binary number ` `    ``static` `int` `count_one(``int` `n) ` `    ``{ ` `        ``int` `c_one = 0; ` `        ``while` `(n != 0) { ` `            ``int` `rem = n % 10; ` ` `  `            ``// counting 1s ` `            ``if` `(rem == 1) ` `                ``c_one = c_one + 1; ` `            ``n = n / 10; ` `        ``} ` `        ``return` `c_one; ` `    ``} ` ` `  `    ``// Check if number is evil or not ` `    ``static` `int` `checkEvil(``int` `n) ` `    ``{ ` `        ``int` `i = 0, bin = 0, n_one = 0; ` ` `  `        ``// converting n to binary form ` `        ``while` `(n != 0) { ` `            ``// calculating remainder ` `            ``int` `r = n % 2; ` ` `  `            ``// storing the remainders in ` `            ``// binary form as a number ` `            ``bin = bin + r * (``int``)(Math.Pow(10, i)); ` `            ``n = n / 2; ` `        ``} ` ` `  `        ``// Calling the count_one function to count ` `        ``// and return number of 1s in bin ` `        ``n_one = count_one(bin); ` `        ``if` `(n_one % 2 == 0) ` `            ``return` `1; ` `        ``else` `            ``return` `0; ` `    ``} ` ` `  `    ``// Driver Code ` `    ``public` `static` `void` `Main(String[] args) ` `    ``{ ` `        ``int` `check, num; ` `        ``num = 32; ` `        ``check = checkEvil(num); ` `        ``if` `(check == 1) ` `            ``Console.WriteLine(num + ``" is Evil Number"``); ` `        ``else` `            ``Console.WriteLine(num + ``" is Odious Number"``); ` `    ``} ` `} ` ` `  `// This code is contributed by vt_m. `

## PHP

 ` `

Output :

```32 is Odius Number
```

This article is contributed by Nikita Tiwari. 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.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.

My Personal Notes arrow_drop_up

Improved By : vt_m, jit_t

Article Tags :
Practice Tags :

Be the First to upvote.

Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.