Special Number | C programming

 Q.9   WAP in C/ C++/ java to check whether the number is a Special Number or not.

Definition: If the sum of the factorial of digits of a number (N) is equal to the number itself, the number (N) is called a special number.

INPUT : 145     The digits of the number are: 1, 4, 5

Factorial of digits:

1! = 1

4! = 4*3*2*1 = 24

5! = 5*4*3*2*1 = 120

Sum of factorial of digits = 1 + 24 + 120 = 145

            Hence, the given number 145 is a special number.

Solution : 

#include <stdio.h>

int factorial(int x) // function to return factorial of the number

{

    int f = 1;

    for (int i = 1; i <= x; i++)

    {

        f = f * i;

    }

    return f;

}

void main()

{

    int n,sum,x;

    printf("\nEnter any positive number : ");

    scanf("%d", &n);

    if (n < 0)

    {

        printf("\nInvalid input! Enter the value again -->");

        main(); // calls the main() function again

    }

    else

    {

        x=n;

        sum = 0;

        while (x > 0)

        {

            sum += factorial(x % 10);

            x = x / 10;

        }

        if(sum == n)

            printf("%d is a Special Number\n",n);

        else

            printf("%d Not a special number\n",n);

    }

} // end of main()