Evil Number - GeeksforGeeks

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.

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

C/C++

// C/C++ program to check if a number is 
// Evil number or Odious Number 
#include <iostream> 
using namespace std; 
#include <math.h> 
  
// 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

<?php 
// PHP program to check if 
// a number is Evil number  
// or Odious Number 
  
// returns number of 1s  
// from the binary number 
function 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 number  
// is evil or not 
function checkEvil($n) 
{ 
    $i = 0; $bin = 0; $n_one = 0; 
      
    // converting n  
    // to binary form 
    while ($n != 0)  
    { 
        // calculating remainder 
        $r = $n % 2; 
          
        // storing the remainders  
        // in binary form as a number 
        $bin = $bin + $r * (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 
$i; $check; $num; 
$num = 32; 
$check = checkEvil($num); 
if ($check == 1) 
    echo $num, " is Evil Number\n"; 
else
    echo $num, " is Odious Number\n"; 
  
// This code is contributed by ajit. 
?> 

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.

Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.

My Personal Notes

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

C/C++

Java

Python

C#

PHP

Recommended Posts: