Question

I need an idea of Java code that will convert an integer (1 to 3,999) into roman numerals using if statements; arrays and loops sadly aren't allowed and that's all I can come up with.

Answer 1

import java.util.Scanner;
public class IntToRoman {
   public static void main(String[] args) {
       //taking input from the user
       Scanner sc = new Scanner (System.in);
   System.out.print("Enter the integer: ");
   int num = sc.nextInt();
   //checking the condition to make sure the number between 1 to 3999
   if ((num < 1 || (num > 3999))) System.out.println("INVALID");
   else System.out.println(convertToRoman(num));
   }
   //logic to convert integer to roman without using arrays or loops
   public static String convertToRoman(int num){
   if (num >= 1000) return "M" + convertToRoman(num - 1000);
   if (num >= 900) return "CM" + convertToRoman(num - 900);
   if (num >= 500) return "D" + convertToRoman(num - 500);
   if (num >= 400) return "CD" + convertToRoman(num - 400);
   if (num >= 100) return "C" + convertToRoman(num - 100);
   if (num >= 90) return "XC" + convertToRoman(num - 90);
   if (num >= 50) return "L" + convertToRoman(num - 50);
   if (num >= 40) return "XL" + convertToRoman(num - 40);
   if (num >= 10) return "X" + convertToRoman(num - 10);
   if (num >= 9) return "IX" + convertToRoman(num - 9);
   if (num >= 5) return "V" + convertToRoman(num - 5);
   if (num >= 4) return "IV" + convertToRoman(num - 4);
   if (num >= 1) return "I" + convertToRoman(num - 1);
       return "";
   }
}