//
// lotto1.cpp
// CSC 215
// John Rogers
//
// This program computes the odds of winning the lottery.
//

#include <iostream.h>

long factorial(long n);

int main()
{
    long numberOfBalls;
    long numberChosen;
    long odds;

    cout << "How many balls are in the game? ";
    cin >> numberOfBalls;

    cout << "How many balls are chosen from that? ";
    cin >> numberChosen;

    odds = factorial(numberOfBalls) /
           (factorial(numberOfBalls - numberChosen) *
            factorial(numberChosen));

    cout << "The odds of winning are " << odds 
         << ":1." << endl;

    return 0;
}

//
// This computes factorial iteratively.
//
long factorial(long n)
{
  long index;
  long answer;

  answer = 1;
  for (index = 1; index <= n; index++) {
    answer = answer * index;
  }
  return answer;
}