package v1ch03.BigIntegerTest;

import java.math.*;
import java.util.*;

/**
 * This program uses big numbers to compute the odds of winning the grand prize in a lottery.
 * @version 1.20 2004-02-10
 * @author Cay Horstmann
 */
public class BigIntegerTest
{
   public static void main(String[] args)
   {
      Scanner in = new Scanner(System.in);

      System.out.print("How many numbers do you need to draw? ");
      int k = in.nextInt();

      System.out.print("What is the highest number you can draw? ");
      int n = in.nextInt();

      /*
       * compute binomial coefficient n*(n-1)*(n-2)*...*(n-k+1)/(1*2*3*...*k)
       */

      BigInteger lotteryOdds = BigInteger.valueOf(1);

      for (int i = 1; i <= k; i++)
         lotteryOdds = lotteryOdds.multiply(BigInteger.valueOf(n - i + 1)).divide(
               BigInteger.valueOf(i));

      System.out.println("Your odds are 1 in " + lotteryOdds + ". Good luck!");
   }
}