BigIntegerTest.java

package BigInterTest;

import java.math.BigInteger;
import java.util.Scanner;

/**
 * This program uses big numbers to compute the odds of winning the grand prize in a lottery.
 *
 * @author Cay Horstman
 * @version 1.20 2004-02-10
 */
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-l)*(n-2)*...*(n-k+l)/(l*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!");
    }
}