Question

Write java code to create 3 methods that accomplish the below concepts according to simple number theory.

1. Create a file PositiveInteger.java that houses a class called PositiveInteger

2. This class should have one single instance variable called num

This is what I have for the constructor: public PositiveInteger(int number) { num = number; }

The three methods should start with the italicized sections shown below to accomplish the corresponding tasks:

1. public boolean isPerfect () - A number is said to be perfect if it is equal to the sum of all its factors (for obvious reasons the list of factors being considered does not include the number itself). 6 = 3 + 2 + 1, hence 6 is perfect.

2. public boolean isAbundant() - A number is considered to be abundant if the sum of its factors (aside from the number) is greater than the number itself. For example, 12 is abundant since 1+2+3+4+6 = 16 > 12. However, a number like 15, where the sum of the factors is 1 + 3 + 5 = 9, is not abundant

3. public boolean isNarcissistic() - A positive integer is called a narcissistic number if it is equal to the sum of its own digits each raised to the power of the number of digits. For example, 153 is narcissistic because 13 + 53 + 33 = 1 + 125 + 27 = 153.

Any java code help would be appreciated!

Answer 1

Code:-

//import for pow()
import java.lang.Math.*;
  
//create class
public class PositiveInteger{
int num;
//create constructor
public PositiveInteger(int number)
{
num = number;
}
//isPerfect() method find all multiples add them all except the number then
//compare with number
public boolean isPerfect()
{ int sum=0;
for(int i=1;i*i<num;i++){
if(num==i*i)
sum+=i;
else if(num%i==0)
{
sum += i+(num/i);
}
}

if(num==(sum-num))
return true;

return false;

}

//isAbundant() method find all multiples add them all except the number then
//compare with number

public boolean isAbundant()
{ int sum=0;
for(int i=1;i*i<num;i++){
if(num==i*i)
sum+=i;
else if(num%i==0)
{
sum += i+(num/i);
}
}

if(num<(sum-num))
return true;

return false;

}

//isPerfect() method count the number of digits then
//take digit one by one calculate power and to a variable
//then compare variable with number
public boolean isNarcissitic()
{int sum=0;
int temp=num,rem,cnt=0;
while(temp>=1){
temp=temp/10;
cnt++;
}
temp=num;
while(temp>=1){
rem=temp%10;
temp=temp/10;
sum=sum + (int)Math.pow(rem,cnt);
}

if(num==sum)
return true;

return false;

}

//for calling the above functions
public static void main(String []args){
  
PositiveInteger a = new PositiveInteger(6);
PositiveInteger b = new PositiveInteger(12);
PositiveInteger c = new PositiveInteger(153);
//print the output
System.out.println(a.isPerfect());
System.out.println(b.isAbundant());
System.out.println(c.isNarcissitic());
}
}

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