Programming Examples

Java program for Evil Number


Write a Program in Java to input a number and check whether it is an Evil Number or not.

Evil Number: An Evil number is a positive whole number which has even number of 1’s in its binary equivalent.

Example: Binary equivalent of 9 is 1001, which contains even number of 1’s. A few evil numbers are 3, 5, 6, 9….

Design a program to accept a positive whole number and find the binary equivalent of the number and count the number of 1’s in it and display whether it is a Evil number or not with an appropriate message. Output the result in format given below:

Example 1

INPUT : 15

BINARY EQUIVALENT : 1111

NO. OF 1’s : 4

OUTPUT : EVIL NUMBER

Example 2

INPUT : 26

BINARY EQUIVALENT : 11010

NO. OF 1’s : 3

OUTPUT : NOT AN EVIL NUMBER

Solution

import java.util.*;
class EvilNumber
{
    String toBinary(int n) 
    {
        int r;
        String s=""; 
  
        char dig[]={'0','1'}; 
  
        while(n>0)
            {
                r=n%2; 
                s=dig[r]+s; 
                n=n/2;
            }
        return s;
    }
     
    int countOne(String s) 
    {
        int c = 0, l = s.length();
        char ch;
        for(int i=0; i<l; i++)
        {
            ch=s.charAt(i);
            if(ch=='1')
            {
                c++;
            }
        }
        return c;
    }
     
    public static void main(String args[])
    {
        EvilNumber ob = new EvilNumber();
        Scanner sc = new Scanner(System.in);
         
        System.out.print("Enter a positive number : ");
        int n = sc.nextInt();
         
        String bin = ob.toBinary(n);
        System.out.println("Binary Equivalent = "+bin);
         
        int x = ob.countOne(bin);
        System.out.println("Number of Ones = "+x);
         
        if(x%2==0)
            System.out.println(n+" is an Evil Number.");
        else
            System.out.println(n+" is Not an Evil Number.");
    }
}
Output

Enter a positive number : 15

Binary Equivalent = 1111

Number of Ones = 4

15 is an Evil Number.

Enter a positive number : 420

Binary Equivalent = 110100100

Number of Ones = 4

420 is an Evil Number.

Enter a positive number : 3

Binary Equivalent = 11

Number of Ones = 2

3 is an Evil Number.

Enter a positive number : 26

Binary Equivalent = 11010

Number of Ones = 3

26 is Not an Evil Number.

CCC Online Test 2021 CCC Practice Test Hindi Python Programming Tutorials Best Computer Training Institute in Prayagraj (Allahabad) Best Java Training Institute in Prayagraj (Allahabad) Best Python Training Institute in Prayagraj (Allahabad) O Level Online Test in Hindi Bank SSC Railway TET UPTET Question Bank career counselling in allahabad Sarkari Naukari Notification Best Website and Software Company in Allahabad Sarkari Exam Quiz