Recursive Combinations Fomula implementation in C c(n,k)=c(n-1,k)+c(n-1,k-1)

combinations.c

/*                                                             
 *                                                             
 * Recursive Combinations Fomula implementation in C                     
 *     c(n,k)=c(n-1,k)+c(n-1,k-1)                              
 *                                                             
 * */                                                          
                                                               
long combine ( int n, int r )                                  
{                                                              
    if ( (n==r) || (r==0) || (n==0) )                          
        return 1;                                              
    return ( combine ( (n-1), r ) + combine ( (n-1), (r-1) )); 
}