BigIntegerTest.java Source code

Introduction

Here is the source code for BigIntegerTest.java

Source

/*
 This program is a part of the companion code for Core Java 8th ed.
 (http://horstmann.com/corejava)
    
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation, either version 3 of the License, or
 (at your option) any later version.
    
 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
    
 You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

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.
 * 
 * @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!");
    }
}