Java program to check for Fascinating Number

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

Fascinating Numbers : Some numbers of 3 digits or more exhibit a very interesting property. The property is such that, when the number is multiplied by 2 and 3, and both these products are concatenated with the original number, all digits from 1 to 9 are present exactly once, regardless of the number of zeroes.

Let’s understand the concept of Fascinating Number through the following example:

Consider the number 192,
192 x 1 = 192
192 x 2 = 384
192 x 3 = 576

Concatenating the results : 192384576

It could be observed that ‘192384576’ consists of all digits from 1 to 9 exactly once. Hence, it could be concluded that 192 is a Fascinating Number.

Some examples of fascinating Numbers are : 192, 219, 273, 327, 1902, 1920, 2019 etc.

Programming Code:

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/** * The class FascinatingNumber inputs a number and checks if it a Fascinating Number or not * @author : www.guideforschool.com * @Program Type : BlueJ Program - Java */   import java.util.*; class FascinatingNumber {     boolean isUnique(String q)     {         int A[] = {0,0,0,0,0,0,0,0,0,0}; //to store frequency of every digit from '0' to '9'         int i, flag = 0;         char ch;         for(i=0; i<q.length(); i++)         {             ch = q.charAt(i);             A[ch-48]++;             /*  increasing A[5] if ch='5' as '5'-48 = 53-48=5              *  (ASCII values of '0' to '9' are 48 to 57) */         }           for(i=1; i<10; i++)         {             //checking if every digit from '1' to '9' are present exactly once or not             if(A[i]!=1)             {                 flag = 1; //flag is set to 1 if frequency is not 1                 break;             }         }           if(flag == 1)             return false;         else             return true;     }     public static void main(String args[])     {         Scanner sc = new Scanner(System.in);         FascinatingNumber ob = new FascinatingNumber();           System.out.print("Enter a number : ");         int n = sc.nextInt();         String p = Integer.toString(n); //converting the number to String           if(p.length()<3)             System.out.println("Number should be of atleast 3 digits.");           else         {             String s = Integer.toString(n*1) + Integer.toString(n*2) + Integer.toString(n*3);             /*  Joining the first, second and third multiple of the number              *  by converting them to Strings and concatenating them*/             if(ob.isUnique(s))                 System.out.println(n+" is a Fascinating Number.");             else                 System.out.println(n+" is not a Fascinating Number.");         }           } }

Output:

Enter a number : 273 273 is a Fascinating Number.   Enter a number : 853 853 is not a Fascinating Number.   Enter a number : 95 Number should be of atleast 3 digits.