➤ Even Number in Java
➤ Odd Number in Java
➤ Prime Number in Java
➤ Twin Prime Number
➤ Magic Number in Java
➤ Neon Number in Java
➤ Tech Number in Java
➤ Harshad Number
➤ Armstrong Number
➤ Palindrome Number
➤ Perfect Number in Java
➤ Pronic Number in Java
➤ Spy Number in Java
➤ Kaprekar Number
➤ Automorphic Number
➤ Krishnamurthy Number
➤ Sunny Number in Java
➤ Buzz Number in Java
➤ Evil Number in Java
➤ Duck Number in Java
➤ Nelson Number in Java
➤ Strong Number in Java
➤ Java Special Number
➤ Disarium Number
Java Number Program Using String
➤ Unique Number in Java
➤ Fascinating Number
➤ ISBN Number in Java
In this post, we will develop a Java program to check whether the given number is a Fascinating Number or not? We will also develop a Java program to find all fascinating numbers between two given numbers.
A number is called a fascinating number if it is (having at least 3 digits) multiplied by 2 and 3, and both these products are concatenated with the original number, then the new number contains all the digits from 1 to 9 exactly once. There could be any number of zeros and are ignored.
Example:-
Number = 192
Multiplying by 2 => 192 * 2 = 384
Multiplying by 3 => 192 * 3 = 576
Concatenation => “192” + “384” + “576” = 192384576, which contains all the digits from 1 to 9 exactly once. Hence, it is a fascinating number.
Since 192 is a fascinating number so, 1902, 19002, 19000…0002, are also a fascinating number. Because number of 0 is ignored.
Another example:-
Number = 273
Multiplying by 2 => 273 * 2 = 546
Multiplying by 3 => 273 * 3 = 819
Concatenation => “273” + “546” + “819” = “273546819”, which contains all the digits from 1 to 9 exactly once. Hence, it is a fascinating number.
Procedure
1) Take a number
2) Declare a string and initialize it with the concatenation of number, number*2, and number*3. For concatenation, we can use + operator
String str = "" + number + number*2 + number*3;
3) Declare an integer array of size 10, by default are all elements of an array is 0
4) Traverse through the characters of the string.
- Find the ith character in ith iteration
- Convert this character into digit (Not in ASCII value) and
- Check array[digit] is 0 or not? If yes then increase the value of array[digit] element by 1. But if array[digit] is not 0 that means already it is increased due to previous existing same digit so, number is not a fascinating number.
If( arr[digit] == 0 ) arr[digit]++;
else return false;
5) Now, check the missing digit, ignore element=0. If any element of the array is zero then it means string (number) doesn’t contain that number. So, the number is not a fascinating number.
6) If all previous conditions are satisfied then it is a fascinating number.
Program
import java.util.Scanner;
public class FascinatingNumber {
// Method to check the Fascinating number
public static boolean isFascinating(int number){
// declare variables
int digit = 0;
// new number
String str = "" + number +
number*2 + number*3;
// declare an array of size 10
int arr[] = new int[10];
// compare array elements and
// characters of the string
for(int i=0; i<str.length(); i++) {
// fetch ith character and
// convert it into number
digit = str.charAt(i) - '0';
// check arr[digit] element
// and ignore 0
if(digit==0 || arr[digit]==0)
arr[digit]++;
else return false;
}
// check their is any
// missing number.
// Ignore 1st element (0) of array
for(int i=1; i<arr.length; i++) {
// digit i was not their in String
if(arr[i]==0)
return false;
}
// all conditions satisfied so, return true
return true;
}
// main method
public static void main(String[] args) {
// declare variables
int number = 0;
boolean result = false;
//create Scanner class object to take input
Scanner scan = new Scanner(System.in);
// take input from end-user
System.out.print("Enter an integer number::");
number = scan.nextInt();
// check number is Fascinating number or not
result = isFascinating(number);
// display
if(result)
System.out.println(number +
" is a Fascinating number.");
else
System.out.println(number +
" is not a Fascinating number.");
// close Scanner class object
scan.close();
}
}
The Output for the different test-cases are:-
Enter an integer number::192
192 is a Fascinating number.
Enter an integer number::1902
1902 is a Fascinating number.
Enter an integer number::219
219 is a Fascinating number.
Enter an integer number::1234
1234 is not a Fascinating number.
Java program to find all fascinating number between two numbers
import java.util.Scanner;
public class FascinatingNumberInRange {
// method to check the Fascinating number
public static boolean isFascinating(int number) {
// declare variables
int digit = 0;
// new number
String str = "" + number + number*2 + number*3;
// declare an array of size 10
int arr[] = new int[10];
// compare array elements and
// characters of the string
for(int i=0; i<str.length(); i++) {
// fetch ith character and
// convert it into number
digit = str.charAt(i) - '0';
// check arr[digit] element
// and ignore 0
if(digit==0 || arr[digit]==0)
arr[digit]++;
else return false;
}
// check their is any
// missing number.
// Ignore 1st element (0) of array
for(int i=1; i<arr.length; i++) {
// digit i was not their in String
if(arr[i]==0)
return false;
}
// all conditions satisfied so, return true
return true;
}
public static void main(String[] args) {
// declare variables
int minRange = 0, maxRange = 0;
//create Scanner class object to take input
Scanner scan = new Scanner(System.in);
System.out.print("Enter minimum value of range:");
minRange = scan.nextInt();
System.out.print("Enter maximum value of range:");
maxRange = scan.nextInt();
System.out.println("The Fascinating number from "+
minRange + " to "+ maxRange+" are: ");
// loop
for(int i=minRange; i<=maxRange; i++) {
// check number
if(isFascinating(i))
System.out.print(i +" ");
}
// close Scanner class object
scan.close();
}
}
The Output for the different test-cases are:-
Enter minimum
value of range:1
Enter maximum
value of range:1000
The Fascinating number from 1 to 1000 are:192 219 273 327
Enter minimum
value of range:1000
Enter maximum
value of range:10000
The Fascinating number from 1000 to 10000 are:1902 1920 2019 2190 2703 2730 3027 3270
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