Expert: Zlatko - 3/30/2011

Question
#include <iostream>
using namespace std;

int binomial(int n, int k); //function prototype

int _tmain()
{
  int n, k ;   // parameters for the binomial number
  int result ;  

  cout << endl ;

  // read in n & k  

  cout << "Enter n (positive integer) :  " ;
  cin >> n ;

  cout << "Enter k (positive integer) : " ;
  cin >> k ;

  result = binomial (n,k);

  cout << "Binomial number " << n << "C" << k
       << " = " << result << endl ;   
  return 0;
}

// ********************************************************

int binomial(int n, int k)

/* Computes the binomial coefficient nCk */
/*                                       */
/* Inputs:                               */
/* n, k (integers)                       */
/*                                       */
/* Output:                               */
/*    binomial coefficient nCk (integer) */

{
int numerator, denominator ;
int i ; // needed to compute numerator & denominator

if (n<k) then
  {
return(0) ;
}
else
  {
denominator = k ; // initial value

for (i= n-k+1; i <=n ; i = i+1)
denominator =  *  ;


return (n) ;
} // else if
} // end function binomial


I am trying to write the code for the if then statement and anything else that you can help with

Answer
Hi Christopher

There is no "then" in the C "if" statement.
It's simply written as
if (n<k)
{
 return(0) ;
}

The formula for nCk can be written with factorials as
factorial(n) / (factorial(k) * factorial(n-k))
so try writing a factorial function and have the binomial function use the factorial function.

Best regards
Zlatko