/* 10(a). w.a.p. to read 2 integer numbers n & r. write a function to calculate factorial of a number. using the function calculate : (a) n!/(n-r)!     (b) n!/((n-r)! * r!)  */

 

#include<stdio.h>
#include<conio.h>
void main()
{
    long int n,r,t1,t2,t3; /* Variable Declarations */
    long int fact(long int x); /* Function Prototype */
    clrscr();
    printf("Enter a numbers n & r : ");
    scanf("%ld %ld",&n,&r);
    if ((n>0) && (r>0) && ((n-r)>0))
    {
        /* Calling 'fact' function */
        t1=fact(n-r);
        t2=fact(n);
        t3=fact(r);
        printf("\nFactorial value of n!/(n-r)! is %ld",(t2/t1));
        printf("\nFactorial value of n!/((n-r)! * r!) is %ld",(t2/(t1*t3)));
    }
    else printf("!!! Invalid Entry. Please try again. !!!");
    getch();
}
long int x;   
                                                                                                                                                         long int fact(x) /* Function Definition 'fact' to find factorial value */
{

    long int tot,i;
    if (x <= 0)
    {
        return(1);
    }
    else
    {
        tot = 1;
        for (i=x; i>=1; i--)
        {
            tot = tot * i;
         }
    }
    return(tot);
}