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++ 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 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 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 number 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 Number")
else:
print(num, "is Odious Number")
# Contributed by Harshit Agrawal
// 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 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.
?>
<script>
// Javascript program to check if a number
// is Evil number or Odious Number
// Returns number of 1s from
// the binary number
function count_one(n)
{
let c_one = 0;
while (n != 0)
{
let rem = n % 10;
// Counting 1s
if (rem == 1)
c_one = c_one + 1;
n = parseInt(n / 10, 10);
}
return c_one;
}
// Check if number is evil or not
function checkEvil(n)
{
let i = 0, bin = 0, n_one = 0;
// Converting n to binary form
while (n != 0)
{
// Calculating remainder
let r = n % 2;
// Storing the remainders in
// binary form as a number
bin = bin + r * (Math.pow(10, i));
n = parseInt(n / 2, 10);
}
// 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
let check, num;
num = 32;
check = checkEvil(num);
if (check == 1)
document.write(num + " is Evil Number");
else
document.write(num + " is Odious Number");
// This code is contributed by suresh07
</script>
Output32 is Odious Number
Time Complexity: O(log2n)
Auxiliary Space: O(1), As constant extra space is used.
With the use of __builtin_parity(x): This function is used to check the parity of a number. This function returns true(1) if the number has odd parity else it returns false(0) for even parity.
C++
#include <iostream>
using namespace std;
int main()
{
int num = 5;
if (__builtin_parity(num))
cout << num << " is Odious Number\n";
else
cout << num << " is Evil Number\n";
return 0;
}
import java.lang.*;
public class Main {
public static void main(String[] args) {
int num = 5;
if (Integer.bitCount(num) % 2 == 1)
System.out.println(num + " is Odious Number");
else
System.out.println(num + " is Evil Number");
}
}
// This code is contributed by shiv1o43g
# Python code addition
num = 5
if bin(num).count('1') % 2 == 1:
print(num, "is Odious Number")
else:
print(num, "is Evil Number")
# The code is contributed by Nidhi goel.
using System;
class Program {
static void Main(string[] args)
{
int num = 5;
if (Parity(num))
Console.WriteLine(num + " is Odious Number");
else
Console.WriteLine(num + " is Evil Number");
}
static bool Parity(int num)
{
int count = 0;
while (num > 0) {
count++;
num &= num - 1;
}
return (count % 2 == 1);
}
}
// This code is contributed by user_dtewbxkn77n
function isOdiousNumber(num) {
return (num.toString(2).split('1').length - 1) % 2 !== 0;
}
let num = 5;
if (isOdiousNumber(num)) {
console.log(num + " is Odious Number");
} else {
console.log(num + " is Evil Number");
}
// This code is contributed by shivregkec
Time Complexity: O(log2n)
Auxiliary Space: O(1)
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