Permutation and Combination

//Permutation and Combinations

#include<stdio.h>

#include<conio.h>
//Declaration of three functions

long fact(int);

long NCR(int, int);

long NPR(int, int);
//Start of main function

void main()

{

   int n, r;

   long ncr, npr;

   clrscr();

   printf("Enter the value of n and r\n");

   scanf("%d%d",&n,&r);

   if(n<r)

   {

    printf("Output is not possible");

   }

   else

   {

   ncr = NCR(n, r);

   npr = NPR(n, r);

   printf("%dC%d = %ld\n", n, r, ncr);

   printf("%dP%d = %ld\n", n, r, npr);

   }

   getch();

}//End of main

//Body of 2nd function

long NCR(int n, int r)

{

   long R;

   R = fact(n)/(fact(r)*fact(n-r));

   return R;

}
//Body of 3rd function

long NPR(int n, int r)

{

   long R;

   R = fact(n)/fact(n-r);

   return R;

}
//Body of 1st function

long fact(int n)

{

   int i;

   long R = 1;

   for( i = 1 ; i <= n ; i++ )

      R = R*i;

   return ( R );

}