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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()

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