Autobiographical Number in Java with example

In this tutorial, we will write a java program to check whether a given number is Autobiographical number or not.

What is Autobiographical Number?

An autobiographical number is a number N such that the first digit of N represents the count of zeroes in N, the second digit represents the count of ones in N, third digit represents the count of twos in N and so on. For example, 1210 is an autobiographical number because:

Number = 1210
Number of zeroes in 1210 = 1 = first digit of Number
Number of ones in 1210 = 2 = second digit of the Number
Number of twos in 1210 = 1 = third digit of the Number
Number of threes in 1210 = 0 = fourth digit of the Number

How to check if a number is Autobiographical Number?

If sum of the digits of the number is equal to the number of digits in the number then that number is an autobiographical number.

Let’s take the same example that we have seen above.

num = 1210
Number of digits in the num = 4
Sum of the digits of the num = 1+2+1+0 = 4
Number of digits in the num ==  Sum of the digits of the num
Hence num 1210 is an autobiographical number.

Program to check Autobiographical Number in Java

import java.util.*;
public class JavaExample
{
  public static void main(String args[])
  {
    Scanner scanner=new Scanner(System.in);
    System.out.print("Enter the number you want to check: ");
    int number = scanner.nextInt();
    scanner.close();
    //copying value of number in a temp variable
    int temp = number;
    String str = String.valueOf(number);
    int numArray[] = new int[str.length()];
    for(int i = numArray.length - 1; i >= 0; i--)
    {
      numArray[i] = temp % 10;
      temp = temp/10;
    }
    boolean found = true;
    for(int i = 0; i < numArray.length; i++)
    {
      int count = 0;
      for(int j = 0; j < numArray.length; j++)
      {
        if(i == numArray[j])
          count++;
      }
      if(count != numArray[i])
      {
        found = false;
        break;
      }
    }
    if(found)
      System.out.println(number + " is an Autobiographical number.");
    else
      System.out.println(number + " is not an Autobiographical number.");
  }
}

Output:

Enter the number you want to check: 1210
1210 is an Autobiographical number.

Output 2:

Enter the number you want to check: 1234
1234 is not an Autobiographical number.

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